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10 pages, 1370 KiB

Open AccessArticle

Bacterial Cellulose Membranes as Carriers for Nisin: Incorporation, Antimicrobial Activity, Cytotoxicity and Morphology

by Gabriela Ribeiro dos Santos, Victória Soares Soeiro, Carolina Fernanda Talarico, Janaína Artem Ataide, André Moreni Lopes, Priscila Gava Mazzola, Thais Jardim Oliveira, José Martins Oliveira Junior, Denise Grotto and Angela F. Jozala

Polymers 2022, 14(17), 3497; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14173497 - 26 Aug 2022

Cited by 6 | Viewed by 2269

Abstract

Based on the previous study, in which nisin and bacterial cellulose were utilized, this new experiment loads nisin into bacterial cellulose (N–BC) and evaluates the morphological characteristics, cytotoxicity, antimicrobial activity and stability of the developed system. The load efficiency of nisin in BC [...] Read more.

Based on the previous study, in which nisin and bacterial cellulose were utilized, this new experiment loads nisin into bacterial cellulose (N–BC) and evaluates the morphological characteristics, cytotoxicity, antimicrobial activity and stability of the developed system. The load efficiency of nisin in BC was evaluated by an agar diffusion assay, utilizing Lactobacillus sakei, and total proteins. After having found the ideal time and concentration for the loading process, the system stability was evaluated for 100 days at 4, 25 and 37 °C against Staphylococcus aureus and L. sakei. Thus, in this study, there is a system that proves to be efficient, once BC has enhanced the antimicrobial activity of nisin, acting as a selective barrier for other compounds present in the standard solution and protecting the peptide. After 4 h, with 45% of proteins, this activity was almost 2 log₁₀ higher than that of the initial solution. Once the nisin solution was not pure, it is possible to suggest that the BC may have acted as a filter. This barrier enhanced the nisin activity and, as a consequence of the nisin loading, a stable N–BC system formed. The N–BC could create meaningful material for pharmaceutical and food applications. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 3254 KiB

Open AccessArticle

Extraction Optimization of Mucilage from Seeds of Mimosa pudica by Response Surface Methodology

by Syed Nasir Abbas Bukhari, Arshad Ali, Muhammad Ajaz Hussain, Muhammad Tayyab, Nasser F. Alotaibi, Mervat A. Elsherif, Kashaf Junaid and Hasan Ejaz

Polymers 2022, 14(9), 1904; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091904 - 06 May 2022

Cited by 6 | Viewed by 2289

Abstract

Mimosa pudica seed mucilage (MPM) is composed of glucuronoxylan, which is a swellable, pH-responsive and non-toxic biomaterial. Herein, we aimed to extract MPM from M. pudica seeds (MP seeds) to ascertain optimization of extraction conditions to get highest yield by response surface methodology, [...] Read more.

Mimosa pudica seed mucilage (MPM) is composed of glucuronoxylan, which is a swellable, pH-responsive and non-toxic biomaterial. Herein, we aimed to extract MPM from M. pudica seeds (MP seeds) to ascertain optimization of extraction conditions to get highest yield by response surface methodology, via Box-Behnken design (RSM-BBD). MPM was extracted from MP seeds by a hot water extraction method. The effects of four different parameters on the extraction yield of MPM were evaluated: pH of the extraction medium (1–10), seed/water contact time (1–12 h), the temperature of extraction medium (30–90 °C), and seed/water ratio (1:5–1:35 w/v). The maximum yield of MPM obtained by Design-Expert software was 10.66% (10.66 g/100 g) at pH 7, seed/water contact time of 6 h, extraction temperature of 50 °C, and seed/water ratio of 1:20 w/v. The p values of ANOVA were found to be less than 0.0001, which indicated that the extraction yield of MPM was significantly affected by all the study parameters. The results revealed that pH and extraction temperature were the most significant factors affecting the yield of MPM. MPM in compressed tablet form showed pH-responsive on–off switching behavior at pH 7.4 and 1.2 in a reversible manner. MPM in compressed tablet form sustained the release of itopride for 16 h following a super case-II transport mechanism and zero-order release kinetics. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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11 pages, 3764 KiB

Open AccessArticle

Free Radical Copolymerization of Diallylamine and Itaconic Acid for the Synthesis of Chitosan Base Superabsorbent

by Wafa Al-Mughrabi, Abeer O. Al-dossary and Abir Abdel-Naby

Polymers 2022, 14(9), 1707; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091707 - 22 Apr 2022

Cited by 4 | Viewed by 1591

Abstract

Copolymerization of diallylamine (DAA) and itaconic acid (IA) was synthesized using benzoyl peroxide as a free radical initiator, in dioxane as the solvent. The composition of the copolymer was determined by the nitrogen content using Edx. The solubility of the copolymer was also [...] Read more.

Copolymerization of diallylamine (DAA) and itaconic acid (IA) was synthesized using benzoyl peroxide as a free radical initiator, in dioxane as the solvent. The composition of the copolymer was determined by the nitrogen content using Edx. The solubility of the copolymer was also investigated. The water solubility of the synthesized copolymer depends on the comonomers’ ratio. The structure of the copolymer was confirmed by ¹³C-NMR spectroscopy. To increase the water insolubility of the copolymers, and keep their hydrophilicity, the copolymer was allowed to react with chitosan to form a superabsorbent polymeric material (SP). The structure of the synthesized superabsorbent was confirmed using ¹³C-NMR spectroscopy. The thermal property of the (SP) was also investigated by TGA. The investigation of the chitosan-based superabsorbent, as water-retaining agents, was studied. The results revealed that the superabsorbent polymers exhibited a good swelling ability and salt tolerance. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 4582 KiB

Open AccessArticle

Heavy Metal Ions Removal from Aqueous Solutions by Treated Ajwa Date Pits: Kinetic, Isotherm, and Thermodynamic Approach

by Mohammad Azam, Saikh Mohammad Wabaidur, Mohammad Rizwan Khan, Saud I. Al-Resayes and Mohammad Shahidul Islam

Polymers 2022, 14(5), 914; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14050914 - 25 Feb 2022

Cited by 52 | Viewed by 2625

Abstract

In the current study we prepared cost-effective adsorbents based on ajwa date pits to remove Cu(II) ions from aqueous medium. Adsorbents were studied using scanning electron microscopy (SEM), FT-IR, and Brunauer-Emmett-Teller (BET) methods to characterize the surface functionalities, morphology, pore size, and particle [...] Read more.

In the current study we prepared cost-effective adsorbents based on ajwa date pits to remove Cu(II) ions from aqueous medium. Adsorbents were studied using scanning electron microscopy (SEM), FT-IR, and Brunauer-Emmett-Teller (BET) methods to characterize the surface functionalities, morphology, pore size, and particle size. The concentration of Cu(II) ions in the studied samples was determined by atomic adsorption spectrometry technique (AAS). Adsorption method was performed sequentially in a batch system followed by optimization by studying the numerous conditions, for instance the initial amounts of Cu(II) ions, dosages of the adsorbent, contact time, and pH of the solution. The ideal pH observed for maximum adsorption capacity was ~6.5. Langmuir and Freundlich isotherm models correctly predicted the investigation results, with the maximum monolayer adsorption capacities for Cu(II) ions at 328 K being 1428.57 mg/g (treated ajwa date pits, TADP) and 1111.1 mg/g for as produced ajwa date pits (ADP). It was revealed that TADP possess greater adsorption capability than ADP. Recovery investigations revealed that the saturated adsorbents eluted the maximum metal with 0.1 M HCl. Cu(II) ions adsorption was observed to be reduced by 80–89% after the second regeneration cycle. For the raw and chemically processed ajwa date pits adsorbent, the Langmuir model performed significantly better than the Freundlich model. The results demonstrated that the adsorbent made from ajwa date pits could be an economical and environmentally friendly alternative for removing Cu(II) ion pollutant from aqueous media. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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20 pages, 5047 KiB

Open AccessArticle

Antimicrobial Activity of Cellulose Based Materials

by Nicoleta Sorina Nemeş, Cristina Ardean, Corneliu Mircea Davidescu, Adina Negrea, Mihaela Ciopec, Narcis Duţeanu, Petru Negrea, Cristina Paul, Daniel Duda-Seiman and Delia Muntean

Polymers 2022, 14(4), 735; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14040735 - 14 Feb 2022

Cited by 20 | Viewed by 2254

Abstract

Biomaterials available for a wide range of applications are generally polysaccharides. They may have inherent antimicrobial activity in the case of chitosan. However, in order to have specific functionalities, bioactive compounds must be immobilized or incorporated into the polymer matrix, as in the [...] Read more.

Biomaterials available for a wide range of applications are generally polysaccharides. They may have inherent antimicrobial activity in the case of chitosan. However, in order to have specific functionalities, bioactive compounds must be immobilized or incorporated into the polymer matrix, as in the case of cellulose. We studied materials obtained by functionalizing cellulose with quaternary ammonium salts: dodecyl-trimethyl-ammonium bromide (DDTMABr), tetradecyl-trimethyl-ammonium bromide (TDTMABr), hexadecyl-trimethyl ammonium chloride (HDTMACl), some phosphonium salts: dodecyl-triphenyl phosphonium bromide (DDTPPBr) and tri n-butyl-hexadecyl phosphonium bromide (HDTBPBr) and extractants containing sulphur: 2-mercaptobenzothiazole (MBT) and thiourea (THIO). Cel-TDTMABr material, whose alkyl substituent chain conformation was shortest, showed the best antimicrobial activity for which, even at the lowest functionalization ratio, 1:0.012 (w:w), the microbial inhibition rate is 100% for Staphylococcus aureus, Escherichia coli, and Candida albicans. Among the materials obtained by phosphonium salt functionalization, Cel-DDTPPBr showed a significant bactericidal effect compared to Cel-HDTBPBr. For instance, to the same functionalization ratio = 1:0.1, the inhibition microbial growth rate is maximum in the case of Cel-DDTPPBr for Staphylococcus aureus, Escherichia coli, and Candida albicans. At the same time, for the Cel-HDTBPBr material, the total bactericidal effect is not reached even at the functionalization ratio 1:0.5. This behavior is based on the hydrophobicity difference between the two extractants, DDTPPBr and HDTBPBr. Cel-MBT material has a maximum antimicrobial effect upon Staphylococcus aureus, Escherichia coli, and Candida albicans at functionalized ratio = 1:0.5. Cel-THIO material showed a bacteriostatic and fungistatic effect, the inhibition of microbial growth being a maximum of 76% for Staphylococcus aureus at the functionalized ratio = 1:0.5. From this perspective, biomaterials obtained by SIR impregnation of cellulose can be considered a benefit to be used to obtain biomass-derived materials having superior antimicrobial properties versus the non-functional support. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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17 pages, 4886 KiB

Open AccessArticle

pH-Induced 3D Printable Chitosan Hydrogels for Soft Actuation

by Sheila Maiz-Fernández, Leyre Pérez-Álvarez, Unai Silván, José Luis Vilas-Vilela and Senentxu Lanceros-Méndez

Polymers 2022, 14(3), 650; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14030650 - 08 Feb 2022

Cited by 18 | Viewed by 3135

Abstract

Three-dimensional (3D) printing represents a suitable technology for the development of biomimetic scaffolds for biomedical and tissue engineering applications. However, hydrogel-based inks’ printability remains a challenge due to their restricted print accuracy, mechanical properties, swelling or even cytotoxicity. Chitosan is a natural-derived polysaccharide [...] Read more.

Three-dimensional (3D) printing represents a suitable technology for the development of biomimetic scaffolds for biomedical and tissue engineering applications. However, hydrogel-based inks’ printability remains a challenge due to their restricted print accuracy, mechanical properties, swelling or even cytotoxicity. Chitosan is a natural-derived polysaccharide that has arisen as a promising bioink due to its biodegradability, biocompatibility, sustainability and antibacterial properties, among others, as well as its ability to form hydrogels under the influence of a wide variety of mechanisms (thermal, ionic, pH, covalent, etc.). Its poor solubility at physiological pH, which has traditionally restricted its use, represents, on the contrary, the simplest way to induce chitosan gelation. Accordingly, herein a NaOH strong base was employed as gelling media for the direct 3D printing of chitosan structures. The obtained hydrogels were characterized in terms of morphology, chemical interactions, swelling and mechanical and rheological properties in order to evaluate the influence of the gelling solution’s ionic strength on the hydrogel characteristics. Further, the influence of printing parameters, such as extrusion speed (300, 600 and 800 mm/min) and pressure (20–35 kPa) and the cytocompatibility were also analyzed. In addition, printed gels show an electro-induced motion due to their polycationic nature, which highlights their potential as soft actuators and active scaffolds. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 5995 KiB

Open AccessArticle

Revealing the Effect of MnO₂, Activated Carbon and MnO₂/Activated Carbon on Chitosan Polymer Host Fabricated Co NPs: Antibacterial Performance and Degradation of Organic Compounds

by Hani S. H. Mohammed Ali, Sumiya, Yasir Anwar, Youssef O. Al-Ghamdi, Muhammad Fakieh and Shahid Ali Khan

Polymers 2022, 14(3), 627; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14030627 - 06 Feb 2022

Cited by 11 | Viewed by 2035

Abstract

MnO₂ and MnO₂ blended with 1 and 2 weight percent of activated carbon (AC), MnO₂/AC1 and MnO₂/AC2 were synthesized through the sol–gel method. The pure chitosan (CS) films were cast in the form of films. Similarly, 5 [...] Read more.

MnO₂ and MnO₂ blended with 1 and 2 weight percent of activated carbon (AC), MnO₂/AC1 and MnO₂/AC2 were synthesized through the sol–gel method. The pure chitosan (CS) films were cast in the form of films. Similarly, 5 weight% of each MnO₂, AC, MnO₂/AC1 and MnO₂/AC2 was intermingled with the CS to produce different films, such as CS-AC, CS-MnO₂, CS-MnO₂/AC1 and CS-MnO₂/AC2. Zero-valent Co NPs were then supported on these films through the chemical reduction method and expressed as CS@Co, CS-AC@Co, CS-MnO₂@Co, CS-MnO₂/AC1@Co and CS-MnO₂/AC2@Co NPs. All the catalysts were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The synthesized catalysts were used as a dip catalyst against the hydrogenation of 4-nitrophenol (4NP), and for the degradation of methyl orange (MO) and Congo red (CR) dyes. The k_app and R² values were deduced from pseudo-first-order kinetics for 4NP and MO and zero-order kinetics for CR dye. The k_app values of CS-AC@Co and CS-MnO₂/AC1@Co NPs for 4NP hydrogenation were higher than those for any other member of the series, at 1.14 × 10⁻¹ and 1.56 × 10⁻¹ min⁻¹ respectively. Similarly, the rate of CR degradation was highest with CS-AC@Co. The R² values for 4NP, MO and CR dyes were above 0.9, which indicated that the application of pseudo-first- and zero-order models were appropriate for this study. Furthermore, the antibacterial activity of all the catalysts was evaluated against Pseudomonas aeruginosa and Escherichia coli. The CS-AC@Co NPs exhibited the highest zone of inhibition compared to other catalysts against P. aeruginosa, while all the catalysts were inactive against E. coli. This study reveals that the catalyst can be used for the degradation of other pollutants and for microbial inhibition. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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11 pages, 13559 KiB

Open AccessArticle

Effects of Extrusion and Irradiation on the Mechanical Properties of a Water–Collagen Solution

by Hynek Chlup, Jan Skočilas, Jaromír Štancl, Milan Houška and Rudolf Žitný

Polymers 2022, 14(3), 578; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14030578 - 31 Jan 2022

Cited by 5 | Viewed by 2058

Abstract

This article describes 1D extension tests on bovine collagen samples (8% collagen in water). At such a high collagen concentration, the mechanical properties of semi-solid samples can be approximated by hyperelastic models (two-parametric HGO and Misof models were used), or simply by Hooke’s [...] Read more.

This article describes 1D extension tests on bovine collagen samples (8% collagen in water). At such a high collagen concentration, the mechanical properties of semi-solid samples can be approximated by hyperelastic models (two-parametric HGO and Misof models were used), or simply by Hooke’s law and the modulus of elasticity E. The experiments confirm a significant increase in the E-modulus of the samples irradiated with high-energy electrons. The modulus E ~ 9 kPa of non-irradiated samples increases monotonically up to E ~ 250 kPa for samples absorbing an e-beam dose of ~3300 Gy. This amplification is attributed to the formation of cross-links by irradiation. However, E-modulus can be increased not only by irradiation but also by exposure to a high strain rate. For example, soft isotropic collagen extruded through a 200 mm long capillary increases the modulus of elasticity from 9 kPa to 30 kPa, and the increase is almost isotropic. This stiffening occurs when the corrugated collagen fibers are straightened and are aligned in the flow direction. It seems that the permanent structural changes caused by extrusion mitigate the effects of the ex post applied irradiation. Irradiation of extruded samples by 3300 Gy increases the modulus of E-elasticity only three times (from 30 kPa to approximately 90 kPa). Extruded and ex post irradiated samples show slight anisotropy (the stiffness in the longitudinal direction is on an average greater than the transverse stiffness). Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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23 pages, 6766 KiB

Open AccessArticle

Highly Stretchable Bacterial Cellulose Produced by Komagataeibacter hansenii SI1

by Izabela Cielecka, Małgorzata Ryngajłło, Waldemar Maniukiewicz and Stanisław Bielecki

Polymers 2021, 13(24), 4455; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13244455 - 19 Dec 2021

Cited by 14 | Viewed by 3421

Abstract

A new strain of bacteria producing cellulose was isolated from Kombucha and identified as Komagataeibacter hansenii, named SI1. In static conditions, the strain synthesises bacterial nanocellulose with an improved ability to stretch. In this study, utilisation of various carbon and nitrogen sources [...] Read more.

A new strain of bacteria producing cellulose was isolated from Kombucha and identified as Komagataeibacter hansenii, named SI1. In static conditions, the strain synthesises bacterial nanocellulose with an improved ability to stretch. In this study, utilisation of various carbon and nitrogen sources and the impact of initial pH was assessed in terms of bacterial nanocellulose yield and properties. K. hansenii SI1 produces cellulose efficiently in glycerol medium at pH 5.0–6.0 with a yield of 3.20–3.60 g/L. Glucose medium led to the synthesis of membrane characterised by a strain of 77%, which is a higher value than in the case of another Komagataeibacter species. Supplementation of medium with vitamin C results in an enhanced porosity and improves the ability of bacterial nanocellulose to stretch (up to 123%). The properties of modified membranes were studied by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and mechanical tests. The results show that bacterial nanocellulose produced in SH medium and vitamin C-supplemented medium has unique properties (porosity, tensile strength and strain) without changing the chemical composition of cellulose. The method of production BNC with altered properties was the issue of Polish patent application no. P.431265. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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13 pages, 15056 KiB

Open AccessArticle

Characterization of Birch Wood Residue after 2-Furaldehyde Obtaining, for Further Integration in Biorefinery Processing

by Maris Puke, Daniela Godina, Mikelis Kirpluks, Prans Brazdausks and Janis Rizikovs

Polymers 2021, 13(24), 4366; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13244366 - 13 Dec 2021

Cited by 6 | Viewed by 1796

Abstract

Latvia is a large manufacturer of plywood in Eastern Europe, with an annual production of 250,000 m³. In Latvia’s climatic conditions, birch (Betula pendula) is the main tree species that is mainly used for plywood production. A significant part [...] Read more.

Latvia is a large manufacturer of plywood in Eastern Europe, with an annual production of 250,000 m³. In Latvia’s climatic conditions, birch (Betula pendula) is the main tree species that is mainly used for plywood production. A significant part of the processed wood makes up residues like veneer shorts, cores, and cut-offs (up to 30%), which have a high potential for value-added products. The aim of this research was to comprehensively characterize lignocellulosic (LC) biomass that was obtained after 2-furaldehyde production in terms of further valorization of this resource. The polymeric cellulose-enriched material can be used in the new biorefinery concept for the production of 2-furaldehyde, acetic acid, cellulose pulp, thermomechanical (TMP) and an alkaline peroxide mechanical (APMP) pulping process. In addition, we experimentally developed the best 2-furaldehyde production conditions to optimize the purity and usability of cellulose in the leftovers of the LC material. The best experimental results in terms of both 2-furaldehyde yield and the purity of residual lignocellulose were obtained if the catalyst concentration was 70%, the catalyst amount was 4 wt.%, the reaction temperature was 175 °C,and the treatment time was 60 min. After process optimization with DesignExpert11, we concluded that the best conditions for maximal glucose content (as cellulose fibers) was a catalyst concentration of 85%, a catalyst amount of 5 wt.%, a temperature of 164 °C, and a treatment time of 52 min. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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21 pages, 1933 KiB

Open AccessArticle

Malva parviflora Leaves Mucilage: An Eco-Friendly and Sustainable Biopolymer with Antioxidant Properties

by Ans Munir, Fadia S. Youssef, Saiqa Ishtiaq, Sairah H. Kamran, Alaa Sirwi, Safwat A. Ahmed, Mohamed L. Ashour and Sameh S. Elhady

Polymers 2021, 13(23), 4251; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234251 - 03 Dec 2021

Cited by 7 | Viewed by 2876

Abstract

Malva parviflora L. is an edible and medicinal herb containing mucilaginous cells in its leaves. Mucilage obtained from M. parviflora leaves (MLM) was extracted in distilled water (1:10 w/v) at 70 °C followed by precipitation with alcohol. Preliminary phytochemical tests [...] Read more.

Malva parviflora L. is an edible and medicinal herb containing mucilaginous cells in its leaves. Mucilage obtained from M. parviflora leaves (MLM) was extracted in distilled water (1:10 w/v) at 70 °C followed by precipitation with alcohol. Preliminary phytochemical tests were performed to assess the purity of the extracted mucilage. Results showed that the yield of mucilage was 7.50%, and it was free from starch, alkaloids, glycosides, saponins, steroids, lipids and heavy metals. MLM had 16.19% carbohydrates, 13.55% proteins and 4.76% amino acids, which indicate its high nutritional value. Physicochemical investigations showed that MLM is neutral and water-soluble, having 5.84% moisture content, 15.60% ash content, 12.33 swelling index, 2.57 g/g water-holding capacity and 2.03 g/g oil-binding capacity. The functional properties, including emulsion capacity, emulsion stability, foaming capacity and stability increased with increased concentrations. Micromeritic properties, such as bulk density, tapped density, Carr’s index, Hausner ratio, and angle of repose, were found to be 0.69 g/cm³, 0.84 g/cm³, 17.86%, 1.22 and 28.5, respectively. Scanning electron microscopy (SEM) showed that MLM is an amorphous powder possessing particles of varying size and shape; meanwhile, rheological studies revealed the pseudoplastic behavior of MLM. The thermal transition process of MLM revealed by a differential scanning calorimetry (DSC) thermogram, occurring at a reasonable enthalpy change (∆H), reflects its good thermal stability. The presence of functional groups characteristic of polysaccharides was ascertained by the infrared (IR) and gas chromatography/mass spectrometry (GC/MS) analyses. GC revealed the presence of five neutral monosaccharides; namely, galactose, rhamnose, arabinose, glucose and mannose, showing 51.09, 10.24, 8.90, 1.80 and 0.90 mg/g of MLM, respectively. Meanwhile, galacturonic acid is the only detected acidic monosaccharide, forming 15.06 mg/g of MLM. It showed noticeable antioxidant activity against the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical with an IC₅₀ value of 154.27 µg/mL. It also prevented oxidative damage to DNA caused by the Fenton reagent, as visualized in gel documentation system. The sun protection factor was found to be 10.93 ± 0.15 at 400 µg/mL. Thus, MLM can be used in food, cosmetic and pharmaceutical industry and as a therapeutic agent due to its unique properties. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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11 pages, 840 KiB

Open AccessArticle

Physicochemical Properties and Digestion Resistance of Acetylated Starch Obtained from Annealed Starch

by Ewa Zdybel, Aleksandra Wilczak, Małgorzata Kapelko-Żeberska, Ewa Tomaszewska-Ciosk, Artur Gryszkin, Anna Gawrońska and Tomasz Zięba

Polymers 2021, 13(23), 4141; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234141 - 27 Nov 2021

Cited by 3 | Viewed by 1660

Abstract

One of the examples of physical starch modifications is the retention of a starch suspension in water having a temperature slightly lower than the pasting temperature (annealing). The aim of this study was to investigate the effect of the annealing process performed at [...] Read more.

One of the examples of physical starch modifications is the retention of a starch suspension in water having a temperature slightly lower than the pasting temperature (annealing). The aim of this study was to investigate the effect of the annealing process performed at various temperatures as the first stage of starch modification. The annealed starch preparations were then esterified using acetic acid anhydride. Finally, the annealed and acetylated starch preparations were determined for their properties. The annealing of starch before acetylation triggered changes in the properties of the modified preparations. It contributed to a higher degree of starch substitution with acetic acid residues and to the increased swelling power of starch. Both these properties were also affected by the annealing temperature. The highest resistance to amylolysis was found in the case of the starch preparation annealed at 53.5 °C and acetylated. The double modification involving annealing and acetylation processes increased the onset and end pasting temperatures compared to the acetylation alone. Similar observations were made for the consistency coefficient and yield point. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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17 pages, 5502 KiB

Open AccessArticle

Antibacterial Films of Alginate-CoNi-Coated Cellulose Paper Stabilized Co NPs for Dyes and Nitrophenol Degradation

by Yasir Anwar, Hani S. H. Mohammed Ali, Waseeq Ur Rehman, Hassan A. Hemeg and Shahid Ali Khan

Polymers 2021, 13(23), 4122; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234122 - 26 Nov 2021

Cited by 8 | Viewed by 1610

Abstract

The development of a solid substrate for the support and stabilization of zero-valent metal nanoparticles (NPs) is the heart of the catalyst system. In the current embodiment, we have prepared solid support comprise of alginate-coated cellulose filter paper (Alg/FP) for the synthesis and [...] Read more.

The development of a solid substrate for the support and stabilization of zero-valent metal nanoparticles (NPs) is the heart of the catalyst system. In the current embodiment, we have prepared solid support comprise of alginate-coated cellulose filter paper (Alg/FP) for the synthesis and stabilization of Co nanoparticles (NPs) named as Alg/FP@Co NPs. Furthermore, Alginate polymer was blended with 1 and 2 weight percent of CoNi NPs to make Alg-CoNi1/FP and Alg-CoNi2/FP, respectively. All these stabilizing matrixes were used as dip-catalyst for the degradation of azo dyes and reduction of 4-nitrophenol (4NP). The effect of initial dye concentration, amount of NaBH₄, and catalyst dosage was assessed for the degradation of Congo red (CR) dye by using Alg-CoNi2/FP@Co NPs. Results indicated that the highest k_app value (3.63 × 10⁻¹ min⁻¹) was exhibited by Alg-CoNi2/FP@Co NPs and lowest by Alg/FP@Co NPs against the discoloration of CR dye. Furthermore, it was concluded that Alg-CoNi2/FP@Co NPs exhibited strong catalyst activity against CR, and methyl orange dye (MO) degradation as well as 4NP reduction. Antibacterial activity of the prepared composites was also investigated and the highest l activity was shown by Alg-CoNi2/FP@Co NPs, which inhibit 2.5 cm zone of bacteria compared to other catalysts. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 3179 KiB

Open AccessArticle

Carboxymethyl Cellulose Hydrogel from Biomass Waste of Oil Palm Empty Fruit Bunch Using Calcium Chloride as Crosslinking Agent

by Nur Fattima’ Al-Zahara’ Tuan Mohamood, Abdul Hakam Abdul Halim and Norhazlin Zainuddin

Polymers 2021, 13(23), 4056; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234056 - 23 Nov 2021

Cited by 28 | Viewed by 5333

Abstract

Carboxymethyl cellulose (CMC) is modified cellulose extracted from oil palm empty fruit bunch (OPEFB) biomass waste that has been prepared through etherification using sodium monochloroacetate (SMCA) in the presence of sodium hydroxide. In this research, CMC hydrogel was prepared using calcium chloride (CaCl [...] Read more.

Carboxymethyl cellulose (CMC) is modified cellulose extracted from oil palm empty fruit bunch (OPEFB) biomass waste that has been prepared through etherification using sodium monochloroacetate (SMCA) in the presence of sodium hydroxide. In this research, CMC hydrogel was prepared using calcium chloride (CaCl₂) as the chemical crosslinker. Throughout the optimization process, four important parameters were studied, which were: (1) CMC concentration, (2) CaCl₂ concentration, (3) reaction time, and (4) reaction temperature. From the results, the best gel content obtained was 28.11% at 20% (w/v) of CMC with 1% (w/v) of CaCl₂ in 24 h reaction at room temperature. Meanwhile, the degree of swelling for CMC hydrogel was 47.34 g/g. All samples were characterized using FT-IR, XRD, TGA, and FESEM to study and compare modification on the OPEFB cellulose. The FT-IR spectrum of CMC hydrogel showed a shift of COO⁻ peaks at 1585 cm⁻¹ and 1413 cm⁻¹, indicating the substitution of Ca²⁺ into the CMC molecular chains. The XRD diffractogram of CMC hydrogel showed no observation of sharp peaks, which signified an amorphous hydrogel phase. The CrI value also proved the decrement of the crystalline nature of CMC hydrogel. TGA–DTG thermograms showed that the T_max of CMC hydrogel at 293.33 °C is slightly better in thermal stability compared to CMC. Meanwhile, the FESEM micrograph of CMC hydrogel showed interconnected pores indicating the crosslinkages in CMC hydrogel. CMC hydrogel was successfully synthesized using CaCl₂ as a crosslinking agent, and its swelling ability can be used in various applications such as drug delivery systems, industrial effluent, food additives, heavy metal removal, and many more. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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23 pages, 4216 KiB

Open AccessArticle

Extrusion and Injection Molding of Poly(3-Hydroxybutyrate-co-3-Hydroxyhexanoate) (PHBHHx): Influence of Processing Conditions on Mechanical Properties and Microstructure

by Chris Vanheusden, Pieter Samyn, Bart Goderis, Mouna Hamid, Naveen Reddy, Anitha Ethirajan, Roos Peeters and Mieke Buntinx

Polymers 2021, 13(22), 4012; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13224012 - 20 Nov 2021

Cited by 12 | Viewed by 4154

Abstract

Biobased and biodegradable polyhydroxyalkanoates (PHAs) have great potential as sustainable packaging materials. However, improvements in their processing and mechanical properties are necessary. In this work, the influence of melt processing conditions on the mechanical properties and microstructure of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is examined using [...] Read more.

Biobased and biodegradable polyhydroxyalkanoates (PHAs) have great potential as sustainable packaging materials. However, improvements in their processing and mechanical properties are necessary. In this work, the influence of melt processing conditions on the mechanical properties and microstructure of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is examined using a full factorial design of experiments (DoE) approach. We have found that strict control over processing temperature, mold temperature, screw speed, and cooling time leads to highly increased elongation at break values, mainly under influence of higher mold temperatures at 80 °C. Increased elongation of the moldings is attributed to relaxation and decreased orientation of the polymer chains together with a homogeneous microstructure at slower cooling rates. Based on the statistically substantiated models to determine the optimal processing conditions and their effects on microstructure variation and mechanical properties of PHBHHx samples, we conclude that optimizing the processing of this biopolymer can improve the applicability of the material and extend its scope in the realm of flexible packaging applications. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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13 pages, 3759 KiB

Open AccessArticle

Lignin Biopolymer for the Synthesis of Iron Nanoparticles and the Composite Applied for the Removal of Methylene Blue

by Fang-Yi Peng, Pei-Wen Wang, Weisheng Liao and Ing-Song Yu

Polymers 2021, 13(21), 3847; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213847 - 07 Nov 2021

Cited by 2 | Viewed by 2001

Abstract

In the current study, lignin, an abundant natural polymer, was dissolved in ethylene glycol and acidic H₂O to form nanoscale lignin. Then, zero-valent iron (ZVI) nanoparticles were synthesized in nanoscale lignin, producing a nZVI/n-lignin composite, via the borohydride reduction method. The [...] Read more.

In the current study, lignin, an abundant natural polymer, was dissolved in ethylene glycol and acidic H₂O to form nanoscale lignin. Then, zero-valent iron (ZVI) nanoparticles were synthesized in nanoscale lignin, producing a nZVI/n-lignin composite, via the borohydride reduction method. The use of nZVI/n-lignin for environmental remediation was tested by the removal of methylene blue in aqueous solutions at room temperature. The nZVI/n-lignin composite achieved a higher methylene blue removal ratio than that achieved by traditional nZVIs. Moreover, its excellent dispersibility in water and stability against oxidation in the air were observed. The functions of the nanoscale lignin in the composite material are (1) prevention of further growth and aggregation of the nZVI nanoparticles, (2) protection of nZVI from serious oxidation by H₂O/O₂, and (3) allowing better dispersibility of nZVI in aqueous solutions. These three functions are important for the field applications of nZVI/n-lignin, namely, to travel long distances before making contact with environmental pollutants. The present method for producing nZVI/n-lignin is straightforward, and the combination of nZVI and lignin is an efficient and environmentally friendly material for environmental applications. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 1847 KiB

Open AccessArticle

Polymeric Microparticles of Calcium Pectinate Containing Urea for Slow Release in Ruminant Diet

by Myrla Melo, André da Silva, Edson Silva Filho, Ronaldo Oliveira, Jarbas Silva Junior, Juliana Paula Oliveira, Antônio Vaz, José Moura, José Pereira Filho and Leilson Bezerra

Polymers 2021, 13(21), 3776; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213776 - 31 Oct 2021

Cited by 7 | Viewed by 1787

Abstract

In ruminant feeding, mechanisms for controlling the rate of ammonia release in the rumen are important for increasing the efficiency of transforming dietary nitrogen into microbial protein. Three microencapsulated formulations, with increased urea concentrations of 10 (MPec1), 20 (MPec2) and 30% (MPec3) from [...] Read more.

In ruminant feeding, mechanisms for controlling the rate of ammonia release in the rumen are important for increasing the efficiency of transforming dietary nitrogen into microbial protein. Three microencapsulated formulations, with increased urea concentrations of 10 (MPec1), 20 (MPec2) and 30% (MPec3) from the w/w, based on the mass of citrus pectin solution, employ the external ionic gelation/extrusion technique. The properties of microencapsulated urea were examined as a completely randomized design with 5 treatments each with 10 replicates for evaluation, and the ratios of dietary to free urea were compared using 5 fistulated male Santa Ines sheep in a Latin 5 × 5 square design. The degradation kinetics showed that the rate of controlled release from the microencapsulated systems was significantly reduced compared with that of free urea (p < 0.05). The population density of ruminal protozoa increased when sheep received the microencapsulated urea (p < 0.05). The disappearance of dry matter and crude protein reached a degradation plateau during the first minutes for the MPec1 and MPec2 systems and was slower for MPec3. The MPec1 and MPec2 systems presented higher (p < 0.05) blood serum concentrations of albumin, urea nitrogen (BUN), creatinine and total cholesterol and did not affect (p > 0.05) the other blood metabolites. The MPec2 systems are recommended because they consist of microspheres with more (p < 0.05) controlled core release, delaying the peak of urea released in the rumen and BUN without affecting (p < 0.05) ruminal pH and temperature. Microencapsulation with calcium pectinate provided better utilization of urea, reducing the risk of ruminant intoxication. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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12 pages, 2240 KiB

Open AccessArticle

Transformation of Oil Palm Waste-Derived Cellulose into Solid Polymer Electrolytes: Investigating the Crucial Role of Plasticizers

by Cheyma Naceur Abouloula, Muhammad. Rizwan, Vidhya Selvanathan, Rosiyah Yahya, Khaled Althubeiti, Hend I. Alkhammash, Md. Akhtaruzzaman and A. Oueriagli

Polymers 2021, 13(21), 3685; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213685 - 26 Oct 2021

Cited by 3 | Viewed by 1920

Abstract

This study explores the possibility of transforming lignocellulose-rich agricultural waste materials into value-added products. Cellulose was extracted from an empty fruit bunch of oil palm and further modified into carboxymethyl cellulose (CMC), a water-soluble cellulose derivative. The CMC was then employed as the [...] Read more.

This study explores the possibility of transforming lignocellulose-rich agricultural waste materials into value-added products. Cellulose was extracted from an empty fruit bunch of oil palm and further modified into carboxymethyl cellulose (CMC), a water-soluble cellulose derivative. The CMC was then employed as the polymeric content in fabrication of solid polymer electrolyte (SPE) films incorporated with lithium iodide. To enhance the ionic conductivity of the solid polymer electrolytes, the compositions were optimized with different amounts of glycerol as a plasticizing agent. The chemical and physical effects of plasticizer content on the film composition were studied by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. FTIR and XRD analysis confirmed the interaction plasticizer with the polymer matrix and the amorphous nature of fabricated SPEs. The highest ionic conductivity of 6.26 × 10⁻² S/cm was obtained with the addition of 25 wt % of glycerol. By fabricating solid polymer electrolytes from oil palm waste-derived cellulose, the sustainability of the materials can be retained while reducing the dependence on fossil fuel-derived materials in electrochemical devices. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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13 pages, 2080 KiB

Open AccessArticle

Laccase-Mediator System Using a Natural Mediator as a Whitening Agent for the Decolorization of Melanin

by Saerom Park, Dahun Jung, Hyejin Do, Jonghyeon Yun, Dongjun Lee, Soeun Hwang and Sang Hyun Lee

Polymers 2021, 13(21), 3671; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213671 - 25 Oct 2021

Cited by 9 | Viewed by 2250

Abstract

In this study, a laccase-mediator system (LMS) using a natural mediator was developed as a whitening agent for melanin decolorization. Seven natural mediators were used to replace synthetic mediators and successfully overcome the low redox potential of laccase and limited access of melanin [...] Read more.

In this study, a laccase-mediator system (LMS) using a natural mediator was developed as a whitening agent for melanin decolorization. Seven natural mediators were used to replace synthetic mediators and successfully overcome the low redox potential of laccase and limited access of melanin to the active site of laccase. The melanin decolorization activity of laccases from Trametes versicolor (lacT) and Myceliophthora thermophila (lacM) was significantly enhanced using natural mediators including acetosyringone, syringaldehyde, and acetovanillone, which showed low cytotoxicity. The methoxy and ketone groups of natural mediators play an important role in melanin decolorization. The specificity constants of lacT and lacM for melanin decolorization were enhanced by 247 and 334, respectively, when acetosyringone was used as a mediator. LMS using lacM and acetosyringone could also decolorize the melanin present in the cellulose hydrogel film, which mimics the skin condition. Furthermore, LMS could decolorize not only synthetic eumelanin analogs prepared by the oxidation of tyrosine but also natural melanin produced by melanoma cells. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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15 pages, 2199 KiB

Open AccessArticle

Ruminant-Waste Protein Hydrolysates and Their Derivatives as a Bio-Flocculant for Oil Sands Tailing Management

by Jesse Yuzik, Vinay Khatri, Michael Chae, Paolo Mussone and David C. Bressler

Polymers 2021, 13(20), 3533; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13203533 - 14 Oct 2021

Cited by 1 | Viewed by 1840

Abstract

Reclamation of tailings ponds is a critical issue for the oil industry. After years of consolidation, the slurry in tailings ponds, also known as fluid fine tailings, is mainly comprised of residual bitumen, water, and fine clay particles. To reclaim the lands that [...] Read more.

Reclamation of tailings ponds is a critical issue for the oil industry. After years of consolidation, the slurry in tailings ponds, also known as fluid fine tailings, is mainly comprised of residual bitumen, water, and fine clay particles. To reclaim the lands that these ponds occupy, separation of the solid particles from the liquid phase is necessary to facilitate water removal and recycling. Traditionally, synthetic polymers have been used as flocculants to facilitate this process, but they can have negative environmental consequences. The use of biological polymers may provide a more environmentally friendly approach to flocculation, and eventual soil remediation, due to their natural biodegradability. Peptides derived from specified risk materials (SRM), a proteinaceous waste stream derived from the rendering industry, were investigated to assess their viability for this application. While these peptides could achieve >50% settling within 3 h in bench-scale settling tests using kaolinite tailings, crosslinking peptides with glutaraldehyde greatly improved their flocculation performance, leading to a >50% settling in only 10 min. Settling experiments using materials obtained through different reactant ratios during crosslinking identified a local optimum molar reactant ratio of 1:32 (peptide amino groups to glutaraldehyde aldehyde groups), resulting in 81.6% settling after 48 h. Taken together, these data highlight the novelty of crosslinking waste-derived peptides with glutaraldehyde to generate a value-added bioflocculant with potential for tailings ponds consolidation. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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14 pages, 2135 KiB

Open AccessArticle

Comparative Study on Different Modified Preparation Methods of Cellulose Nanocrystalline

by Xinhui Wang, Na Wang, Baoming Xu, Yili Wang, Jinyan Lang, Junliang Lu, Guorong Chen and Heng Zhang

Polymers 2021, 13(19), 3417; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13193417 - 05 Oct 2021

Cited by 8 | Viewed by 2006

Abstract

Different modification process routes are used to improve the modified cellulose nanocrystalline (MCNC) with higher fatty acid by esterification reaction and graft polymerization to obtain certain hydrophobic properties. Two preparation methods, product structure and surface activity, are compared and explored. Experimental results show [...] Read more.

Different modification process routes are used to improve the modified cellulose nanocrystalline (MCNC) with higher fatty acid by esterification reaction and graft polymerization to obtain certain hydrophobic properties. Two preparation methods, product structure and surface activity, are compared and explored. Experimental results show that the modified product is still at the nanometer level and basically retains the crystal structure of the raw cellulose nanocrystalline (CNC). The energy consumption of the two preparation methods is low; however, the esterification method with co-reactant requires short reaction time, and the degree of substitution of the product is high. The modified product prepared by grafting polymerization method has a high HLB value and amphiphilicity, which can effectively reduce the surface tension of water. Therefore, it can be used as a green and environmentally friendly surface-active substance. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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15 pages, 4645 KiB

Open AccessArticle

Phenol–Hyaluronic Acid Conjugates: Correlation of Oxidative Crosslinking Pathway and Adhesiveness

by Jungwoo Kim, Sumin Kim, Donghee Son and Mikyung Shin

Polymers 2021, 13(18), 3130; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13183130 - 16 Sep 2021

Cited by 10 | Viewed by 3675

Abstract

Hyaluronic acid (HA) is a natural polysaccharide with great biocompatibility for a variety of biomedical applications, such as tissue scaffolds, dermal fillers, and drug-delivery carriers. Despite the medical impact of HA, its poor adhesiveness and short-term in vivo stability limit its therapeutic efficacy. [...] Read more.

Hyaluronic acid (HA) is a natural polysaccharide with great biocompatibility for a variety of biomedical applications, such as tissue scaffolds, dermal fillers, and drug-delivery carriers. Despite the medical impact of HA, its poor adhesiveness and short-term in vivo stability limit its therapeutic efficacy. To overcome these shortcomings, a versatile modification strategy for the HA backbone has been developed. This strategy involves tethering phenol moieties on HA to provide both robust adhesiveness and intermolecular cohesion and can be used for oxidative crosslinking of the polymeric chain. However, a lack of knowledge still exists regarding the interchangeable phenolic adhesion and cohesion depending on the type of oxidizing agent used. Here, we reveal the correlation between phenolic adhesion and cohesion upon gelation of two different HA–phenol conjugates, HA–tyramine and HA–catechol, depending on the oxidant. For covalent/non-covalent crosslinking of HA, oxidizing agents, horseradish peroxidase/hydrogen peroxide, chemical oxidants (e.g., base, sodium periodate), and metal ions, were utilized. As a result, HA–catechol showed stronger adhesion properties, whereas HA–tyramine showed higher cohesion properties. In addition, covalent bonds allowed better adhesion compared to that of non-covalent bonds. Our findings are promising for designing adhesive and mechanically robust biomaterials based on phenol chemistry. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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18 pages, 2309 KiB

Open AccessArticle

Production of Thermophilic Chitinase by Paenibacillus sp. TKU052 by Bioprocessing of Chitinous Fishery Wastes and Its Application in N-acetyl-D-glucosamine Production

by Chien Thang Doan, Thi Ngoc Tran and San-Lang Wang

Polymers 2021, 13(18), 3048; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13183048 - 09 Sep 2021

Cited by 14 | Viewed by 2411

Abstract

The bioprocessing of chitinous fishery wastes (CFWs) to chitinases through fermentation approaches has gained importance owing to its great benefits in reducing the enzyme production cost, and utilizing chitin waste. In this work, our study of the chitinase production of Paenibacillus sp. TKU052 [...] Read more.

The bioprocessing of chitinous fishery wastes (CFWs) to chitinases through fermentation approaches has gained importance owing to its great benefits in reducing the enzyme production cost, and utilizing chitin waste. In this work, our study of the chitinase production of Paenibacillus sp. TKU052 in the presence of different kinds of CFWs revealed a preference for demineralized crab shells powder (deCSP); furthermore, a 72 kDa chitinase was isolated from the 0.5% deCSP-containing medium. The Paenibacillus sp. TKU052 chitinase displayed maximum activity at 70 °C and pH 4–5, while Zn²⁺, Fe³⁺, Triton X-100, Tween 40, and SDS exerted a negative effect on its activity, whereas Mn²⁺ and 2-mercaptoethanol were found to potentially enhance the activity. Among various kinds of polysaccharide, Paenibacillus sp. TKU052 chitinase exhibited the best catalytic activity on colloidal chitin (CC) with K_m = 9.75 mg/mL and V_max = 2.43 μmol/min. The assessment of the hydrolysis of CC and N-acetyl chitooligosaccharides revealed that Paenibacillus sp. TKU052 chitinase possesses multiple catalytic functions, including exochitinase, endochitinase, and N-acetyl-β-D-glucosaminidase activities. Finally, the combination of Paenibacillus sp. TKU052 chitinase and Streptomyces speibonae TKU048 N-acetyl-β-D-glucosaminidase could efficiently convert CC to N-acetyl-D-glucosamine (GlcNAc) with a production yield of 94.35–98.60% in 12–24 h. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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20 pages, 15785 KiB

Open AccessArticle

Hydrophobic Modification of Biopolymer Aerogels by Cold Plasma Coating

by Baldur Schroeter, Isabella Jung, Katharina Bauer, Pavel Gurikov and Irina Smirnova

Polymers 2021, 13(17), 3000; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13173000 - 04 Sep 2021

Cited by 10 | Viewed by 3327

Abstract

The aim of this work was to evaluate the potential of cold plasma polymerization as a simple, fast and versatile technique for deposition of protective hydrophobic and oleophobic polymer layers on hydrophilic biopolymer aerogels. Polymerization of different fluorinated monomers (octafluorocyclobutane C₄F [...] Read more.

The aim of this work was to evaluate the potential of cold plasma polymerization as a simple, fast and versatile technique for deposition of protective hydrophobic and oleophobic polymer layers on hydrophilic biopolymer aerogels. Polymerization of different fluorinated monomers (octafluorocyclobutane C₄F₈ and perfluoro-acrylates PFAC-6 and PFAC-8) on aerogel monoliths derived from alginate, cellulose, whey protein isolate (WPI) and potato protein isolate (PPI) resulted in fast and significant surface hydrophobization after short process times of 5 min and led to superhydrophobic surfaces with static water contact angles up to 154° after application of poly-C₄F₈ coatings. Simultaneous introduction of hydro- and oleophobicity was possible by deposition of perfluoro-acrylates. While the porous structure of aerogels stayed intact during the process, polymerization inside the aerogels pores led to the generation of new porous moieties and resulted therefore in significant increase in the specific surface area. The magnitude of the effect depended on the individual process settings and on the overall porosity of the substrates. A maximization of specific surface area increase (+179 m²/g) was obtained by applying a pulsed wave mode in the C₄F₈-coating of alginate aerogels. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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19 pages, 25229 KiB

Open AccessArticle

Chitosan-Urea Nanocomposite for Improved Fertilizer Applications: The Effect on the Soil Enzymatic Activities and Microflora Dynamics in N Cycle of Potatoes (Solanum tuberosum L.)

by Rohini Kondal, Anu Kalia, Ondrej Krejcar, Kamil Kuca, Sat Pal Sharma, Karanvir Luthra, Gurmeet Singh Dheri, Yogesh Vikal, Monica Sachdeva Taggar, Kamel A. Abd-Elsalam and Carmen L. Gomes

Polymers 2021, 13(17), 2887; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13172887 - 27 Aug 2021

Cited by 15 | Viewed by 4611

Abstract

The impact of polymer-based slow-release urea formulations on soil microbial N dynamics in potatoes has been sparingly deciphered. The present study investigated the effect of a biodegradable nano-polymer urea formulation on soil enzymatic activities and microflora involved in the N cycling of potato [...] Read more.

The impact of polymer-based slow-release urea formulations on soil microbial N dynamics in potatoes has been sparingly deciphered. The present study investigated the effect of a biodegradable nano-polymer urea formulation on soil enzymatic activities and microflora involved in the N cycling of potato (Solanum tuberosum L.). The nano-chitosan-urea composite (NCUC) treatment significantly increased the soil dehydrogenase activity, organic carbon content and available potassium compared to the conventional urea (CU) treatment. The soil ammonical nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) contents and urease activity were significantly decreased in the NCUC-amended soil. The slow urea hydrolysis rate led to low concentrations of NH₄⁺-N and NO₃⁻-N in the tested potato soil. Furthermore, these results corroborate the low count of ammonia oxidizer and nitrate reducer populations. Quantitative PCR (q-PCR) studies revealed that the relative abundance of eubacterial (AOB) and archaeal ammonia-oxidizing (AOA) populations was reduced in the NCUC-treated soil compared to CU. The abundance of AOA was particularly lower than AOB, probably due to the more neutral and alkaline conditions of the tested soil. Our results suggest that the biodegradable polymer urea composite had a significant effect on the microbiota associated with soil N dynamics. Therefore, the developed NCUC could be used as a slow N-release fertilizer for enhanced growth and crop yields of potato. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 3420 KiB

Open AccessArticle

Thermal Stability and Decomposition Mechanism of PLA Nanocomposites with Kraft Lignin and Tannin

by Nina Maria Ainali, Evangelia Tarani, Alexandra Zamboulis, Klementina Pušnik Črešnar, Lidija Fras Zemljič, Konstantinos Chrissafis, Dimitra A. Lambropoulou and Dimitrios N. Bikiaris

Polymers 2021, 13(16), 2818; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13162818 - 22 Aug 2021

Cited by 18 | Viewed by 3070

Abstract

Packaging applications cover approximately 40% of the total plastics production, whereas food packaging possesses a high proportion within this context. Due to several environmental concerns, petroleum-based polymers have been shifted to their biobased counterparts. Poly(lactic acid) (PLA) has been proved the most dynamic [...] Read more.

Packaging applications cover approximately 40% of the total plastics production, whereas food packaging possesses a high proportion within this context. Due to several environmental concerns, petroleum-based polymers have been shifted to their biobased counterparts. Poly(lactic acid) (PLA) has been proved the most dynamic biobased candidate as a substitute of the conventional polymers. Despite its numerous merits, PLA exhibits some limitations, and thus reinforcing agents are commonly investigated as fillers to ameliorate several characteristics. In the present study, two series of PLA-based nanocomposites filled with biobased kraft-lignin (KL) and tannin (T) in different contents were prepared. A melt–extrusion method was pursued for nanocomposites preparation. The thermal stability of the prepared nanocomposites was examined by Thermogravimetric Analysis, while thermal degradation kinetics was applied to deepen this process. Pyrolysis–Gas Chromatography/Mass Spectrometry was employed to provide more details of the degradation process of PLA filled with the two polyphenolic fillers. It was found that the PLA/lignin nanocomposites show better thermostability than neat PLA, while tannin filler has a small catalytic effect that can reduce the thermal stability of PLA. The calculated Eα value of PLA-T nanocomposite was lower than that of PLA-KL resulting in a substantially higher decomposition rate constant, which accelerate the thermal degradation. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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13 pages, 2429 KiB

Open AccessArticle

Synthesis, Characterization and Mechanical Properties of Novel Bio-Based Polyurethane Foams Using Cellulose-Derived Polyol for Chain Extension and Cellulose Citrate as a Thickener Additive

by Loredana Maiuolo, Fabrizio Olivito, Vincenzo Algieri, Paola Costanzo, Antonio Jiritano, Matteo Antonio Tallarida, Antonio Tursi, Corradino Sposato, Andrea Feo and Antonio De Nino

Polymers 2021, 13(16), 2802; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13162802 - 20 Aug 2021

Cited by 18 | Viewed by 3251

Abstract

A novel series of bio-based polyurethane composite foams was prepared, employing a cellulose-derived polyol for chain extension and cellulose-citrate as a thickener additive. The utilized polyol was obtained from the reduction reaction of cellulose-derived bio-oil through the use of sodium borohydride and iodine. [...] Read more.

A novel series of bio-based polyurethane composite foams was prepared, employing a cellulose-derived polyol for chain extension and cellulose-citrate as a thickener additive. The utilized polyol was obtained from the reduction reaction of cellulose-derived bio-oil through the use of sodium borohydride and iodine. Primarily, we produced both rigid and flexible polyurethane foams through chain extension of the prepolymers. Secondly, we investigated the role of cellulose citrate as a polyurethane additive to improve the mechanical properties of the realized composite materials. The products were characterized by FT-IR spectroscopy and their morphologies were analysed by SEM. Mechanical tests were evaluated to open new perspectives towards different applications. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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9 pages, 4739 KiB

Open AccessArticle

Albumin Acts as a Lubricant on the Surface of Hydrogel and Silicone Hydrogel Contact Lenses

by Chen-Ying Su, Lung-Kun Yeh, Tzu-Wei Fan, Chi-Chun Lai and Hsu-Wei Fang

Polymers 2021, 13(13), 2051; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13132051 - 23 Jun 2021

Cited by 5 | Viewed by 2547

Abstract

Feeling comfortable is the greatest concern for contact lens wearers, and it has been suggested that in vivo comfort could be corresponded to the in vitro friction coefficient of contact lenses. How tear albumin could affect the friction coefficient of silicone hydrogel and [...] Read more.

Feeling comfortable is the greatest concern for contact lens wearers, and it has been suggested that in vivo comfort could be corresponded to the in vitro friction coefficient of contact lenses. How tear albumin could affect the friction coefficient of silicone hydrogel and hydrogel contact lenses was analyzed by sliding a lens against a quartz glass in normal and extremely high concentration of albumin solution. Albumin deposition testing and surface roughness analysis were also conducted. The results showed that the friction coefficient of tested contact lenses did not correspond to both the albumin deposition amount and surface roughness, but we proposed a model of how albumin might act as a lubricant on the surface of some hydrogel and silicone hydrogel contact lenses. In conclusion, albumin provided lubrication for silicone hydrogel contact lenses regardless of albumin concentrations, while albumin only acted as a lubricant for hydrogel contact under normal concentration. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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18 pages, 2773 KiB

Open AccessArticle

Production of Sucrolytic Enzyme by Bacillus licheniformis by the Bioconversion of Pomelo Albedo as a Carbon Source

by Chien Thang Doan, Thi Ngoc Tran, Thi Thanh Nguyen, Thi Phuong Hanh Tran, Van Bon Nguyen, Trung Dung Tran, Anh Dzung Nguyen and San-Lang Wang

Polymers 2021, 13(12), 1959; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13121959 - 13 Jun 2021

Cited by 5 | Viewed by 2975

Abstract

Recently, there has been increasing use of agro-byproducts in microbial fermentation to produce a variety of value-added products. In this study, among various kinds of agro-byproducts, pomelo albedo powder (PAP) was found to be the most effective carbon source for the production of [...] Read more.

Recently, there has been increasing use of agro-byproducts in microbial fermentation to produce a variety of value-added products. In this study, among various kinds of agro-byproducts, pomelo albedo powder (PAP) was found to be the most effective carbon source for the production of sucrose hydrolyzing enzyme by Bacillus licheniformis TKU004. The optimal medium for sucrolytic enzyme production contained 2% PAP, 0.75% NH₄NO₃, 0.05% MgSO₄, and 0.05% NaH₂PO₄ and the optimal culture conditions were pH 6.7, 35 °C, 150 rpm, and 24 h. Accordingly, the highest sucrolytic activity was 1.87 U/mL, 4.79-fold higher than that from standard conditions using sucrose as the carbon source. The purified sucrolytic enzyme (sleTKU004) is a 53 kDa monomeric protein and belongs to the glycoside hydrolase family 68. The optimum temperature and pH of sleTKU004 were 50 °C, and pH = 6, respectively. SleTKU004 could hydrolyze sucrose, raffinose, and stachyose by attacking the glycoside linkage between glucose and fructose molecules of the sucrose unit. The K_m and V_max of sleTKU004 were 1.16 M and 5.99 µmol/min, respectively. Finally, sleTKU004 showed strong sucrose tolerance and presented the highest hydrolytic activity at the sucrose concentration of 1.2 M–1.5 M. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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14 pages, 3483 KiB

Open AccessArticle

Isolation and Characterization of Alpha and Nanocrystalline Cellulose from Date Palm (Phoenix dactylifera L.) Trunk Mesh

by Hamid M. Shaikh, Arfat Anis, Anesh Manjaly Poulose, Saeed M. Al-Zahrani, Niyaz Ahamad Madhar, Abdullah Alhamidi and Mohammad Asif Alam

Polymers 2021, 13(11), 1893; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13111893 - 07 Jun 2021

Cited by 40 | Viewed by 4743

Abstract

Highly pure cellulosic polymers obtained from waste lignocellulose offer great potential for designing novel materials in the concept of biorefinery. In this work, alpha-cellulose and nanocrystalline cellulose were isolated from the date palm trunk mesh (DPTM) through a series of physicochemical treatments. Supercritical [...] Read more.

Highly pure cellulosic polymers obtained from waste lignocellulose offer great potential for designing novel materials in the concept of biorefinery. In this work, alpha-cellulose and nanocrystalline cellulose were isolated from the date palm trunk mesh (DPTM) through a series of physicochemical treatments. Supercritical carbon dioxide treatment was used to remove soluble extractives, and concentrated alkali pretreatment was used to eliminate the lignin portion selectively to obtain alpha-cellulose in approximately 94% yield. Further treatments of this cellulose yielded nanocrystalline cellulose. The structure–property relationship studies were carried out by characterizing the obtained polymers by various standard methods and analytical techniques such as Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray diffraction (EDX-XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Almost 65% yield of pure cellulose was achieved, out of which 94% is the alpha-cellulose. This cellulose shows good thermal stability and crystallinity. The microscopic analysis of the nanocellulose showed a heterogeneous mix of irregular-shaped particles with a size range of 20–60 nm. The percentage crystallinity of alpha-cellulose and nanocellulose was found to be 68.9 and 71.8, respectively. Thus, this study shows that, this DPTM-based low-cost waste biomass can be a potential source to obtain cellulose and nano-cellulose. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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15 pages, 2583 KiB

Open AccessArticle

Double-Cross-Linked Networks Based on Methacryloyl Mucin

by Elena Olăreț, Brîndușa Bălănucă, Andra Mihaela Onaș, Jana Ghițman, Horia Iovu, Izabela-Cristina Stancu and Andrada Serafim

Polymers 2021, 13(11), 1706; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13111706 - 23 May 2021

Cited by 11 | Viewed by 2921

Abstract

Mucin is a glycoprotein with proven potential in the biomaterials field, but its use is still underexploited for such applications. The present work aims to produce a synthesis of methacryloyl mucin single-network (SN) hydrogels and their double-cross-linked-network (DCN) counterparts. Following the synthesis of [...] Read more.

Mucin is a glycoprotein with proven potential in the biomaterials field, but its use is still underexploited for such applications. The present work aims to produce a synthesis of methacryloyl mucin single-network (SN) hydrogels and their double-cross-linked-network (DCN) counterparts. Following the synthesis of the mucin methacryloyl derivative, various SN hydrogels are prepared through the photopolymerization of methacrylate bonds, using reaction media with different pH values. The SN hydrogels are converted into DCN systems via supplementary cross-linking in tannic acid aqueous solution. The chemical modification of mucin is described, and the obtained product is characterized; the structural modification of mucin is assessed through FTIR spectroscopy, and the circular dichroism and the isoelectric point of methacryloyl mucin is evaluated. The affinity for aqueous media of both SN and DCN hydrogels is estimated, and the mechanical properties of the systems are assessed, both at macroscale through uniaxial compression and rheology tests and also at microscale through nanoindentation tests. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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13 pages, 3419 KiB

Open AccessArticle

Extraction and Physicochemical Characterization of Dried Powder Mucilage from Opuntia ficus-indica Cladodes and Aloe Vera Leaves: A Comparative Study

by María Carolina Otálora, Andrea Wilches-Torres and Jovanny A. Gómez Castaño

Polymers 2021, 13(11), 1689; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13111689 - 22 May 2021

Cited by 26 | Viewed by 6900

Abstract

Cactaceae and Asphodelaceae are native desert plants known for their high mucilage content, which is a polysaccharide of growing interest in the food, cosmetic, and pharmaceutical industries. In this study, powdered mucilage was obtained from cladodes of Opuntia ficus-indica (OFI) and aloe vera [...] Read more.

Cactaceae and Asphodelaceae are native desert plants known for their high mucilage content, which is a polysaccharide of growing interest in the food, cosmetic, and pharmaceutical industries. In this study, powdered mucilage was obtained from cladodes of Opuntia ficus-indica (OFI) and aloe vera (AV) leaves, and their molecular, morphological, and thermal properties were investigated and compared. Additionally, their dietary fiber content was determined. Three-dimensional molecular models were calculated for both mucilages using ab initio methods. Vibrational spectra (FTIR and Raman) revealed intramolecular interactions and functional groups that were specified with the help of theoretical ab initio and semi-empirical calculations. SEM micrographs measured at magnifications of 500× and 2000× demonstrated significantly different superficial and internal morphologies between these two mucilages. Thermal analysis using DSC/TGA demonstrated superior thermal stability for the OFI mucilage. The dietary fiber content in OFI mucilage was more than double that of AV mucilage. Our results show that both dehydrated mucilages present adequate thermal and nutritional properties to be used as functional ingredients in industrial formulations; however, OFI mucilage exhibited better physicochemical and functional characteristics than AV mucilage as a raw material. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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13 pages, 8543 KiB

Open AccessArticle

Conversion of Pectin-Containing By-Products to Pectinases by Bacillus amyloliquefaciens and Its Applications on Hydrolyzing Banana Peels for Prebiotics Production

by Chien Thang Doan, Chien-Lin Chen, Van Bon Nguyen, Thi Ngoc Tran, Anh Dzung Nguyen and San-Lang Wang

Polymers 2021, 13(9), 1483; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13091483 - 04 May 2021

Cited by 14 | Viewed by 3122

Abstract

The utilization of pectin-containing by-products may be useful in a variety of fields. This study aims to establish the processing of pectin-containing by-products to produce pectinases using Bacillus amyloliquefaciens TKU050 strain. In this study, several kinds of agricultural pectin-containing by-products from banana (banana [...] Read more.

The utilization of pectin-containing by-products may be useful in a variety of fields. This study aims to establish the processing of pectin-containing by-products to produce pectinases using Bacillus amyloliquefaciens TKU050 strain. In this study, several kinds of agricultural pectin-containing by-products from banana (banana peel), rice (rice bran), orange (orange peel), coffee (spent coffee grounds), and wheat (wheat bran) were utilized to provide carbon sources for the production of a pectinase by B. amyloliquefaciens TKU050. B. amyloliquefaciens TKU050 expressed the highest pectinase productivity (0.76 U/mL) on 0.5% wheat bran-containing medium at 37°C for four days. A 58 kDa pectinase was purified from the four-day cultured medium fermented under optimized culture conditions with 7.24% of a recovery ratio and 0.51 U/mg of specific activity, respectively. The optimum temperature, optimum pH, thermal stability, and pH stability of the TKU050 pectinase were 50 °C, pH 6, <50 °C, and pH 6–9, respectively. The TKU050 pectinase was inhibited by sodium dodecyl sulfate and Cu²⁺. The reducing sugar obtained by hydrolyzing banana peel with TKU050 pectinase showed the growth-enhancing effect on the growth of four tested lactic acid bacteria. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 5353 KiB

Open AccessArticle

New Hyaluronic Acid/Polyethylene Oxide-Based Electrospun Nanofibers: Design, Characterization and In Vitro Biological Evaluation

by Oana Maria Ionescu, Arn Mignon, Andreea Teodora Iacob, Natalia Simionescu, Luminita Georgeta Confederat, Cristina Tuchilus and Lenuța Profire

Polymers 2021, 13(8), 1291; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13081291 - 15 Apr 2021

Cited by 10 | Viewed by 2224

Abstract

Natural compounds have been used as wound-healing promoters and are also present in today’s clinical proceedings. In this research, different natural active components such as propolis, Manuka honey, insulin, L-arginine, and Calendula officinalis infusion were included into hyaluronic acid/poly(ethylene)oxide-based electrospun nanofiber membranes to [...] Read more.

Natural compounds have been used as wound-healing promoters and are also present in today’s clinical proceedings. In this research, different natural active components such as propolis, Manuka honey, insulin, L-arginine, and Calendula officinalis infusion were included into hyaluronic acid/poly(ethylene)oxide-based electrospun nanofiber membranes to design innovative wound-dressing biomaterials. Morphology and average fiber diameter were analyzed by scanning electron microscopy. Chemical composition was proved by Fourier transform infrared spectroscopy, which indicated successful incorporation of the active components. The nanofiber membranes with propolis and Calendula officinalis showed best antioxidant activity, cytocompatibility, and antimicrobial properties against pathogen strains Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa and had an average diameter of 217 ± 19 nm with smooth surface aspect. Water vapor transmission rate was in agreement with the range suitable for preventing infections or wound dehydration (~5000 g/m² 24 h). Therefore, the developed hyaluronic acid/poly(ethylene)oxide nanofibers with additional natural components showed favorable features for clinical use as wound dressings. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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15 pages, 2462 KiB

Open AccessArticle

Combination of Computational Techniques to Obtain High-Quality Gelatin-Base Gels from Chicken Feet

by José C. C. Santana, Poliana F. Almeida, Nykael Costa, Isabella Vasconcelos, Flavio Guerhardt, Dimitria T. Boukouvalas, Wonder A. L. Alves, Pedro C. Mendoza, Felix M. C. Gamarra, Segundo A. V. Llanos, Sidnei A. Araujo, Ada P. B. Quispe, Rosangela M. Vanalle and Fernando T. Berssaneti

Polymers 2021, 13(8), 1289; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13081289 - 15 Apr 2021

Cited by 2 | Viewed by 2142

Abstract

With the increasing global population, it has become necessary to explore new alternative food sources to meet the increasing demand. However, these alternatives sources should not only be nutritive and suitable for large scale production at low cost, but also present good sensory [...] Read more.

With the increasing global population, it has become necessary to explore new alternative food sources to meet the increasing demand. However, these alternatives sources should not only be nutritive and suitable for large scale production at low cost, but also present good sensory characteristics. Therefore, this situation has influenced some industries to develop new food sources with competitive advantages, which require continuous innovation by generating and utilising new technologies and tools to create opportunities for new products, services, and industrial processes. Thus, this study aimed to optimise the production of gelatin-base gels from chicken feet by response surface methodology (RSM) and facilitate its sensorial classification by Kohonen’s self-organising maps (SOM). Herein, a 2² experimental design was developed by varying sugar and powdered collagen contents to obtain grape flavoured gelatin from chicken feet. The colour, flavour, aroma, and texture attributes of gelatines were evaluated by consumers according to a hedonic scale of 1–9 points. Least squares method was used to develop models relating the gelatin attributes with the sugar content and collagen mass, and their sensorial qualities were analysed and classified using the SOM algorithm. Results showed that all gelatin samples had an average above six hedonic points, implying that they had good consumer acceptance and can be marketed. Furthermore, gelatin D, with 3.65–3.80% (w/w) powdered collagen and 26.5–28.6% (w/w) sugar, was determined as the best. Thus, the SOM algorithm proved to be a useful computational tool for comparing sensory samples and identifying the best gelatin product. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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20 pages, 5272 KiB

Open AccessArticle

Green Natural Rubber Composites Reinforced with Black/White Rice Husk Ashes: Effects of Reinforcing Agent on Film’s Mechanical and Dielectric Properties

by Praewpakun Sintharm and Muenduen Phisalaphong

Polymers 2021, 13(6), 882; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13060882 - 13 Mar 2021

Cited by 10 | Viewed by 3506

Abstract

Green natural rubber (NR) composites reinforced with black rice husk ash (BRHA)/white rice husk ash (WRHA), using alginate as a thickening and dispersing agent and crosslinking by CaCl₂, was developed to improve mechanical, chemical and dielectric properties of NR-based films by [...] Read more.

Green natural rubber (NR) composites reinforced with black rice husk ash (BRHA)/white rice husk ash (WRHA), using alginate as a thickening and dispersing agent and crosslinking by CaCl₂, was developed to improve mechanical, chemical and dielectric properties of NR-based films by using a latex aqueous microdispersion process. A maximum of 100 per hundred rubbers (phr) of rice husk ashes (RHAs) could be integrated in NR matrix without phase separation. Mechanical properties of the composite films were considerably enhanced, compared to the neat NR film. The composite films reinforced with WRHA demonstrated relatively better mechanical properties than those reinforced with BRHA, whereas the composites filled with BRHA demonstrated higher elongation at break. The crosslinking by CaCl₂ improved the film tensile strength but lowered the film elasticity. The reinforcement strongly improved chemical resistance of the composite films in toluene. The films are biodegradable in soil, with weight loss of 7.6–18.3% of the initial dry weight after 3 months. Dielectric constant and dielectric loss factors of the composite films were enhanced with RHAs loading. According to the obtained properties, the composites offer potential for further development as stretchable conductive substrate or semiconducting polymer films for electronic applications. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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11 pages, 4340 KiB

Open AccessArticle

Effects of Lyophilization on the Release Profiles of 3D Printed Delivery Systems Fabricated with Carboxymethyl Cellulose Hydrogel

by Xuepeng Jiang, Yanhua Huang, Yiliang Cheng, Zhan Zhang, Xiaolei Shi and Hantang Qin

Polymers 2021, 13(5), 749; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13050749 - 28 Feb 2021

Cited by 6 | Viewed by 2972

Abstract

Recently, increasing numbers of researchers are becoming interested in 3D bioprinting because it provides customizability and structural complexity, which is difficult for traditional subtractive manufacturing to achieve. One of the most critical factors in bioprinting is the material. Depending on the bio-applications, materials [...] Read more.

Recently, increasing numbers of researchers are becoming interested in 3D bioprinting because it provides customizability and structural complexity, which is difficult for traditional subtractive manufacturing to achieve. One of the most critical factors in bioprinting is the material. Depending on the bio-applications, materials should be bio-inert or bio-active, non-toxic, and along with those characteristics, mechanical properties should also meet the applicational or manufacturing requirement. As previously validated for bioprinting, carboxymethyl cellulose (CMC) hydrogel is focused on the printability and release control test in this study. With a differentiated weight percentage of CMC hydrogels were used to 3D print capsules filled with food degradable colorant at designated voids to mimic capsules manufactured for oral delivery. Standard USP (United States Pharmacopeia) dissolution apparatus II (Paddle) evaluations were performed both on lyophilized and non-lyophilized printed capsules. The first-order model was selected due to high linear fitting regression. Upon 24 h dissolution, non-lyophilized capsules showed a different release efficiency when the CMC percentage varied, while lyophilized capsules showed no significant difference. This study signifies the possibility of customizing oral drug delivery by printing capsules with CMC hydrogel. The improved delivery efficiency demonstrated by capsules with post-process lyophilizing proposed potential optimization options for pharmaceutical manufacturing industries. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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18 pages, 3795 KiB

Open AccessArticle

X-ray Photoelectron Spectroscopy Analysis of Chitosan–Graphene Oxide-Based Composite Thin Films for Potential Optical Sensing Applications

by Wan Mohd Ebtisyam Mustaqim Mohd Daniyal, Yap Wing Fen, Silvan Saleviter, Narong Chanlek, Hideki Nakajima, Jaafar Abdullah and Nor Azah Yusof

Polymers 2021, 13(3), 478; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13030478 - 02 Feb 2021

Cited by 25 | Viewed by 3470

Abstract

In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan–graphene oxide (chitosan–GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co²⁺). From the XPS results, [...] Read more.

In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan–graphene oxide (chitosan–GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co²⁺). From the XPS results, it was confirmed that carbon, oxygen, and nitrogen elements existed on the PAR–chitosan–GO thin film, while for CdS QD–chitosan–GO, the existence of carbon, oxygen, cadmium, nitrogen, and sulfur were confirmed. Further deconvolution of each element using the Gaussian–Lorentzian curve fitting program revealed the sub-peak component of each element and hence the corresponding functional group was identified. Next, investigation using surface plasmon resonance (SPR) optical sensor proved that both chitosan–GO-based thin films were able to detect Co²⁺ as low as 0.01 ppm for both composite thin films, while the PAR had the higher binding affinity. The interaction of the Co²⁺ with the thin films was characterized again using XPS to confirm the functional group involved during the reaction. The XPS results proved that primary amino in the PAR–chitosan–GO thin film contributed more important role for the reaction with Co²⁺, as in agreement with the SPR results. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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16 pages, 5301 KiB

Open AccessArticle

One-Step Synthesis of Eu³⁺-Modified Cellulose Acetate Film and Light Conversion Mechanism

by Zhihui Zhang, Zhengdong Zhao, Yujia Lu, Di Wang, Chengyu Wang and Jian Li

Polymers 2021, 13(1), 113; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13010113 - 30 Dec 2020

Cited by 16 | Viewed by 2694

Abstract

A CA-Eu(III) complex was synthesized by the coordination reaction of cellulose acetate (CA) and Eu³⁺ to obtain a CA-Eu light conversion film. This product was then doped with Tb(III) to sensitize the luminescence of Eu³⁺, which could functionalize the CA [...] Read more.

A CA-Eu(III) complex was synthesized by the coordination reaction of cellulose acetate (CA) and Eu³⁺ to obtain a CA-Eu light conversion film. This product was then doped with Tb(III) to sensitize the luminescence of Eu³⁺, which could functionalize the CA film. FTIR and XPS showed that the oxygen atoms in C=O, C–O (O=C–O), and O–H were involved in the complexation with Eu³⁺ and formed a Eu–O bond. SEM revealed that Eu³⁺ filled in the pores of the CA film. By changing the experimental conditions, the best fluorescence performance was obtained at the CA: Eu³⁺ ratio of 3:1 with a reaction time of 65 min. The energy transfer between Tb³⁺–Eu³⁺ could be realized by doping Tb³⁺ to enhance the luminescence of Eu³⁺. The best fluorescence performance of the CA-Eu-Tb light conversion film was at a Eu³⁺:Tb³⁺ ratio of 3:1. Compared with the CA film, the light conversion film has high transparency, high tensile strength, and good flexibility. It can convert the ultraviolet light harmful to plants into red light that is beneficial to photosynthesis. This offers high efficiency and environmental protection in the field of agricultural films. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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30 pages, 2459 KiB

Open AccessReview

Recent Advances in Chemically Modified Cellulose and Its Derivatives for Food Packaging Applications: A Review

by Zhuolun Jiang and To Ngai

Polymers 2022, 14(8), 1533; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14081533 - 10 Apr 2022

Cited by 29 | Viewed by 5928

Abstract

The application of cellulose in the food packaging field has gained increasing attention in recent years, driven by the desire for sustainable products. Cellulose can replace petroleum-based plastics because it can be converted to biodegradable and nontoxic polymers from sustainable natural resources. These [...] Read more.

The application of cellulose in the food packaging field has gained increasing attention in recent years, driven by the desire for sustainable products. Cellulose can replace petroleum-based plastics because it can be converted to biodegradable and nontoxic polymers from sustainable natural resources. These products have increasingly been used as coatings, self-standing films, and paperboards in food packaging, owing to their promising mechanical and barrier properties. However, their utilization is limited because of the high hydrophilicity of cellulose. With the presence of a large quantity of functionalities within pristine cellulose and its derivatives, these building blocks provide a unique platform for chemical modification via covalent functionalization to introduce stable and permanent functionalities to cellulose. A primary aim of chemical attachment is to reduce the probability of component leaching in wet and softened conditions and to improve the aqueous, oil, water vapor, and oxygen barriers, thereby extending its specific use in the food packaging field. However, chemical modification may affect the desirable mechanical, thermal stabilities and biodegradability exhibited by pristine cellulose. This review exhaustively reports the research progress on cellulose chemical modification techniques and prospective applications of chemically modified cellulose for use in food packaging, including active packaging. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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32 pages, 3524 KiB

Open AccessReview

Polymer-Based Constructs for Flexor Tendon Repair: A Review

by Jef Brebels and Arn Mignon

Polymers 2022, 14(5), 867; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14050867 - 23 Feb 2022

Cited by 10 | Viewed by 6363

Abstract

A flexor tendon injury is acquired fast and is common for athletes, construction workers, and military personnel among others, treated in the emergency department. However, the healing of injured flexor tendons is stretched over a long period of up to 12 weeks, therefore, [...] Read more.

A flexor tendon injury is acquired fast and is common for athletes, construction workers, and military personnel among others, treated in the emergency department. However, the healing of injured flexor tendons is stretched over a long period of up to 12 weeks, therefore, remaining a significant clinical problem. Postoperative complications, arising after traditional tendon repair strategies, include adhesion and tendon scar tissue formation, insufficient mechanical strength for early active mobilization, and infections. Various researchers have tried to develop innovative strategies for developing a polymer-based construct that minimalizes these postoperative complications, yet none are routinely used in clinical practice. Understanding the role such constructs play in tendon repair should enable a more targeted approach. This review mainly describes the polymer-based constructs that show promising results in solving these complications, in the hope that one day these will be used as a routine practice in flexor tendon repair, increasing the well-being of the patients. In addition, the review also focuses on the incorporation of active compounds in these constructs, to provide an enhanced healing environment for the flexor tendon. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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24 pages, 17681 KiB

Open AccessReview

Surface Modified Nanocellulose and Its Reinforcement in Natural Rubber Matrix Nanocomposites: A Review

by Nik Muhammad Faris Hakimi, Seng Hua Lee, Wei Chen Lum, Siti Fatahiyah Mohamad, Syeed SaifulAzry Osman Al Edrus, Byung-Dae Park and Anis Azmi

Polymers 2021, 13(19), 3241; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13193241 - 24 Sep 2021

Cited by 16 | Viewed by 3405

Abstract

Natural rubber is of significant economic importance owing to its excellent resilience, elasticity, abrasion and impact resistance. Despite that, natural rubber has been identified with some drawbacks such as low modulus and strength and therefore opens up the opportunity for adding a reinforcing [...] Read more.

Natural rubber is of significant economic importance owing to its excellent resilience, elasticity, abrasion and impact resistance. Despite that, natural rubber has been identified with some drawbacks such as low modulus and strength and therefore opens up the opportunity for adding a reinforcing agent. Apart from the conventional fillers such as silica, carbon black and lignocellulosic fibers, nanocellulose is also one of the ideal candidates. Nanocellulose is a promising filler with many excellent properties such as renewability, biocompatibility, non-toxicity, reactive surface, low density, high specific surface area, high tensile and elastic modulus. However, it has some limitations in hydrophobicity, solubility and compatibility and therefore it is very difficult to achieve good dispersion and interfacial properties with the natural rubber matrix. Surface modification is often carried out to enhance the interfacial compatibilities between nanocellulose and natural rubber and to alleviate difficulties in dispersing them in polar solvents or polymers. This paper aims to highlight the different surface modification methods employed by several researchers in modifying nanocellulose and its reinforcement effects in the natural rubber matrix. The mechanism of the different surface medication methods has been discussed. The review also lists out the conventional filler that had been used as reinforcing agent for natural rubber. The challenges and future prospective has also been concluded in the last part of this review. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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24 pages, 2953 KiB

Open AccessReview

A Comprehensive Review on Plant-Derived Mucilage: Characterization, Functional Properties, Applications, and Its Utilization for Nanocarrier Fabrication

by Mansuri M. Tosif, Agnieszka Najda, Aarti Bains, Ravinder Kaushik, Sanju Bala Dhull, Prince Chawla and Magdalena Walasek-Janusz

Polymers 2021, 13(7), 1066; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13071066 - 28 Mar 2021

Cited by 83 | Viewed by 15166

Abstract

Easily sourced mucus from various plant parts is an odorless, colorless and tasteless substance with emerging commercial potential in agriculture, food, cosmetics and pharmaceuticals due to its non-toxic and biodegradable properties. It has been found that plant-derived mucilage can be used as a [...] Read more.

Easily sourced mucus from various plant parts is an odorless, colorless and tasteless substance with emerging commercial potential in agriculture, food, cosmetics and pharmaceuticals due to its non-toxic and biodegradable properties. It has been found that plant-derived mucilage can be used as a natural thickener or emulsifier and an alternative to synthetic polymers and additives. Because it is an invisible barrier that separates the surface from the surrounding atmosphere, it is used as edible coatings to extend the shelf life of fresh vegetables and fruits as well as many food products. In addition to its functional properties, mucilage can also be used for the production of nanocarriers. In this review, we focus on mucus extraction methods and its use as a natural preservative for fresh produce. We detailed the key properties related to the extraction and preservation of food, the mechanism of the effect of mucus on the sensory properties of products, coating methods when using mucus and its recipe for preserving fruit and vegetables. Understanding the ecological, economic and scientific factors of production and the efficiency of mucus as a multi-directional agent will open up its practical application in many industries. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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27 pages, 2231 KiB

Open AccessReview

Synthetic, Natural, and Semisynthetic Polymer Carriers for Controlled Nitric Oxide Release in Dermal Applications: A Review

by Carolina Gutierrez Cisneros, Veerle Bloemen and Arn Mignon

Polymers 2021, 13(5), 760; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13050760 - 28 Feb 2021

Cited by 24 | Viewed by 4459

Abstract

Nitric oxide (NO•) is a free radical gas, produced in the human body to regulate physiological processes, such as inflammatory and immune responses. It is required for skin health; therefore, a lack of NO• is known to cause or worsen skin conditions related [...] Read more.

Nitric oxide (NO•) is a free radical gas, produced in the human body to regulate physiological processes, such as inflammatory and immune responses. It is required for skin health; therefore, a lack of NO• is known to cause or worsen skin conditions related to three biomedical applications— infection treatment, injury healing, and blood circulation. Therefore, research on its topical release has been increasing for the last two decades. The storage and delivery of nitric oxide in physiological conditions to compensate for its deficiency is achieved through pharmacological compounds called NO-donors. These are further incorporated into scaffolds to enhance therapeutic treatment. A wide range of polymeric scaffolds has been developed and tested for this purpose. Hence, this review aims to give a detailed overview of the natural, synthetic, and semisynthetic polymeric matrices that have been evaluated for antimicrobial, wound healing, and circulatory dermal applications. These matrices have already set a solid foundation in nitric oxide release and their future perspective is headed toward an enhanced controlled release by novel functionalized semisynthetic polymer carriers and co-delivery synergetic platforms. Finally, further clinical tests on patients with the targeted condition will hopefully enable the eventual commercialization of these systems. Full article

(This article belongs to the Special Issue Functional Natural-Based Polymers)

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