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Hydroxyapatite Based Coatings for Biomedical Applications
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Hydroxyapatite Based Coatings for Biomedical Applications

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Coatings for Biomedicine and Bioengineering".

Deadline for manuscript submissions: closed (15 October 2021) | Viewed by 28612

Special Issue Editor

Dr. Simona Liliana Iconaru

E-Mail Website
Guest Editor
National Institute of Materials Physics, Atomistilor Street, No. 405A, P.O. Box MG 07, 077125 Magurele, Romania
Interests: biomaterials; biomedical applications; environmental applications; surface analysis; antimicrobial properties
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

One of the most pressing issues of our society is the global health crisis. During the years, extensive efforts have been made in order to develop new materials which could be successfully implemented in biomedical applications such as drug delivery, tissue engineering, and antimicrobial devices. As a result of an increased incidence of postoperative infections related to implants, the attention of scientists has been directed towards the development of biocompatible and antimicrobial materials that could be used as coatings for implantable medical devices. Hydroxyappatite (HAp), with the general formula Ca10(PO4)6(OH)2, is a bioactive bioceramic chemically similar to the mineral component of hard tissues. Because of its  similarity to human hard tissues and of its outstanding biological and physico-chemical properties, HAp is widely used in biomedical applications for hard tissue replacements, scaffolds, coatings for implantable devices, and as a reinforcement material in biocomposites. Nonetheless, previous studies have reported that HAp coatings do not exhibit antimicrobial properties and are usually responsible for the development of microbial biofilms. In this context, the use of an antimicrobial agents such as silver, zinc, copper, europium, samarium, or cerium ions embedded in a hydroxyapatite matrix has been proposed.

This Special Issue focuses on the design, synthesis, and characterization of antimicrobial materials, such as hydroxyapatite coatings, with antimicrobial properties that could be used in various biomedical applications including tissue engineering, implantable devices, and antimicrobial devices.

Dr. Simona Liliana Iconaru
Guest Editor

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Keywords

  • Hydroxyapatite
  • Coatings
  • Antimicrobial propertis
  • Biocomposites

Published Papers (11 papers)

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Research

20 pages, 4829 KiB  
Article
Influence of the Biological Medium on the Properties of Magnesium Doped Hydroxyapatite Composite Coatings
by Daniela Predoi, Steluta Carmen Ciobanu, Simona Liliana Iconaru and Mihai Valentin Predoi
Coatings 2023, 13(2), 409; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13020409 - 11 Feb 2023
Cited by 9 | Viewed by 1210
Abstract
In this paper, the stability of magnesium-doped hydroxyapatite/chitosan (MHC) suspension obtained with the sol-gel approach was evaluated using nondestructive ultrasound measurements. The MHC coatings obtained by the spin-coating technique were characterized before and after immersion for 7 and 14 days, respectively, in Dulbecco’s [...] Read more.
In this paper, the stability of magnesium-doped hydroxyapatite/chitosan (MHC) suspension obtained with the sol-gel approach was evaluated using nondestructive ultrasound measurements. The MHC coatings obtained by the spin-coating technique were characterized before and after immersion for 7 and 14 days, respectively, in Dulbecco’s modified eagle medium (DMEM) by scanning electron microscopy, equipped with an EDAX detector. Also, the functional groups present on the MHC coatings surface were analyzed with the aid of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The surface microstructure was evaluated using two commentary techniques, namely atomic force microscopy (AFM) and metallographic microscopy (MM). The influence of immersion in DMEM on the biological properties was studied with in vitro studies using primary osteoblast and HCT-8 cell lines. Our results revealed that both surface morphology and chemical composition of the MHC coatings allow rapid development of a new apatite layer on their surface after immersion in DMEM. Preliminary in vitro biological studies underlined the noncytotoxic effect of the studied samples on the proliferation of primary osteoblast and HCT-8 cell lines, which makes them a promising candidate for applications in fields such as orthopedics or dentistry. The antifungal assay of the MHC coatings was assessed using Candida albicans ATCC 10231 and their results showed a good inhibitory effect. The coatings made on the basis of the MHC composite could contribute to increasing the degree of success of implants by decreasing the risk of infections and postoperative inflammation. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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18 pages, 8635 KiB  
Article
Development of Silver Doped Hydroxyapatite Thin Films for Biomedical Applications
by Simona Liliana Iconaru, Daniela Predoi, Carmen Steluta Ciobanu, Mikael Motelica-Heino, Régis Guegan and Coralia Bleotu
Coatings 2022, 12(3), 341; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12030341 - 05 Mar 2022
Cited by 12 | Viewed by 2319
Abstract
Silver doped hydroxyapatite [AgHAp, Ca10−xAg(PO4)6(OH)2], due to its antimicrobial properties, is an advantageous material to be used for various coatings. The AgHAp thin films with xAg = 0.05 and xAg = 0.1 were [...] Read more.
Silver doped hydroxyapatite [AgHAp, Ca10−xAg(PO4)6(OH)2], due to its antimicrobial properties, is an advantageous material to be used for various coatings. The AgHAp thin films with xAg = 0.05 and xAg = 0.1 were achieved using the spin-coating method. The resulting samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis revealed that the particles of both samples are ellipsoidal. Also, in agreement with the results obtained by XRD measurements, the results of the SEM studies have shown that the particles shape is ellipsoidal. Optical properties of silver doped hydroxyapatite thin films deposited on Si substrate were investigated through Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The results obtained by the two complementary techniques highlighted that the molecular structure of the studied samples is not influenced by the increase of the silver concentration in the samples. Our studies revealed that the surface morphology of the obtained samples consist of uniform and continuous layers. The biocompatibility of the obtained thin films was also evaluated with the aid of human osteosarcoma MG63 (ATCC CRL 1427) cell line. Moreover, the in vitro antifungal activity against Candida albicans fungal strain of the AgHAp thin films was studied and the obtained results revealed their antifungal effect. The results of the biological assays showed that the AgHAp thin films are a very promising material for biomedical applications. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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16 pages, 5832 KiB  
Article
Physicochemical Characterization of Europium-Doped Hydroxyapatite Thin Films with Antifungal Activity
by Carmen Steluta Ciobanu, Mihai Valentin Predoi, Nicolas Buton, Christelle Megier, Simona Liliana Iconaru and Daniela Predoi
Coatings 2022, 12(3), 306; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12030306 - 24 Feb 2022
Cited by 6 | Viewed by 1661
Abstract
Owing to its unique biological and physicochemical properties, hydroxyapatite (HAp) represents one of the most extensively studied biomaterials for biomedical applications. It is well known that Candida is currently one of the fungi frequently involved in the onset and development of post-implant infections [...] Read more.
Owing to its unique biological and physicochemical properties, hydroxyapatite (HAp) represents one of the most extensively studied biomaterials for biomedical applications. It is well known that Candida is currently one of the fungi frequently involved in the onset and development of post-implant infections and, owing to the appearance of antifungal resistance, it is quite difficult to treat despite all the tremendous efforts made in this regard by the scientific world. Therefore, in this context, we report for the first time in this paper, the development and characterization of europium-doped thin films (5EuHAp, xEu = 0.05) on a Si substrate by a spin-coating method. The results of ultrasound (US), zeta (ζ) potential, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) studies are presented. The XRD studies conducted on 5EuHAp suspension revealed the nanometric dimensions of the particles and sample purity. In addition, a moderate stability of the 5EuHAp suspension was observed. XPS measurements revealed the presence of Eu 3d in the 5EuHAp thin films. In the SEM micrographs, the surface uniformity and the absence of the surface defects could be observed. Moreover, the results of the FTIR studies showed the presence of the vibrational bands specific to the HAp structure in the studied sample. The antifungal activity of the HAp and 5EuHAp suspensions and coatings was evaluated using the Candida albicans ATCC 10231 (C. albicans) fungal strain. The qualitative assays of the antifungal properties of HAp and 5EuHAp coatings were also visualized by SEM and CLSM. The antifungal studies revealed that both 5EuHAp suspensions and coatings exhibited noticeable antifungal activity against C. albicans cells. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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11 pages, 5490 KiB  
Article
Coating Characteristic of Hydroxyapatite on Titanium Substrates via Hydrothermal Treatment
by Pham Trung Kien, Tran Ngo Quan and Le Huynh Tuyet Anh
Coatings 2021, 11(10), 1226; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11101226 - 09 Oct 2021
Cited by 12 | Viewed by 2203
Abstract
Medical pure titanium (Ti) shows excellent chemical stability and mechanical properties in clinical uses, but its initial fixation with host bone, when implanted, is usually delayed owing to the bioinert Ti surface. In this study, we fabricate the hydroxyapatite (HA)-coated titanium by three [...] Read more.
Medical pure titanium (Ti) shows excellent chemical stability and mechanical properties in clinical uses, but its initial fixation with host bone, when implanted, is usually delayed owing to the bioinert Ti surface. In this study, we fabricate the hydroxyapatite (HA)-coated titanium by three steps reactions: (1) to form an activated O2− layer by immersing Ti substrate into an alkaline solution such as NaOH; (2) the O2− bonds with Ca2+ to form Ca–O–Ti bonding, in which O plays the part of bridge materials between Ca and Ti substrate and (3) the conversion of Ca–O–Ti samples to HA-coated Ti samples by immersion into Na2HPO4 2 M at 180 °C for 48 h using hydrothermal methods. The effect of different phosphate solutions (NaH2PO4 2 M and Na2HPO4 2 M solution) and hydrothermal treatment time (24 and 48 h) on the characteristic of hydroxyapatite coating titanium substrate is also investigated using the optical microscope, thin film XRD and SEM/EDX. The HA-coated Ti samples fabricated by immersion into Na2HPO4 2 M at 180 °C for 48 h show fiber HA covering Titan substrate with a diameter varying from 0.1 to 0.3 µm. These HA-coated Ti samples can be regarded as promising multifunctional biomaterials. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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18 pages, 4434 KiB  
Article
Carbonated Hydroxyapatite-Based Honeycomb Scaffold Coatings on a Titanium Alloy for Bone Implant Application—Physicochemical and Mechanical Properties Analysis
by Mona Sari, Nicholas Adi Kristianto, Chotimah, Ika Dewi Ana and Yusril Yusuf
Coatings 2021, 11(8), 941; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11080941 - 05 Aug 2021
Cited by 18 | Viewed by 3050
Abstract
In this work, carbonated hydroxyapatite (CHA) based on abalone mussel shells (Haliotis asinina) is synthesized using the co-precipitation method. The synthesized CHA was mixed with honeycomb (HCB) 40 wt.% for the scaffold fabrication process. CHA and scaffold CHA/HCB 40 wt.% were used [...] Read more.
In this work, carbonated hydroxyapatite (CHA) based on abalone mussel shells (Haliotis asinina) is synthesized using the co-precipitation method. The synthesized CHA was mixed with honeycomb (HCB) 40 wt.% for the scaffold fabrication process. CHA and scaffold CHA/HCB 40 wt.% were used for coating a Titanium (Ti) alloy using the electrophoretic deposition dip coating (EP2D) method with immersion times of 10, 20, and 30 min. The synthesized B-type CHA with a stirring time of 45 min could have lower transmittance values and smaller crystallite size. Energy dispersive X-ray spectroscopy (EDS) showed that the Ca/P molar ratio was 1.79. The scaffold CHA/HCB 40 wt.% had macropore size, micropore size, and porosity of 102.02 ± 9.88 μm, 1.08 ± 0.086 μm, and 66.36%, respectively, and therefore it can also be applied in the coating process for bone implant applications due to the potential scaffold for bone growth. Thus, it has the potential for coating on Ti alloy applications. In this study, the compressive strength for all immersion time variations was about 54–83 MPa. The average compression strengths of human cancellous bone were about 0.2–80 MPa. The thickness obtained was in accordance with the thickness parameters required for a coating of 50–200 μm. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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12 pages, 2987 KiB  
Article
Sintering of Potassium Doped Hydroxy-Fluorapatite Bioceramics
by Jihen Ben Slimen, Mustapha Hidouri, Marwa Ghouma, Ezzedine Ben Salem and Sergey V. Dorozhkin
Coatings 2021, 11(7), 858; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11070858 - 17 Jul 2021
Cited by 6 | Viewed by 2421
Abstract
The present study describes the influence of potassium and hydroxyl substitutions on the structural, thermal and mechanical properties of fluorapatite bioceramics. A set of non-stoichiometric ion-substituted compounds, with a chemical formula of Ca10−xKx(PO4)6F(2−2 [...] Read more.
The present study describes the influence of potassium and hydroxyl substitutions on the structural, thermal and mechanical properties of fluorapatite bioceramics. A set of non-stoichiometric ion-substituted compounds, with a chemical formula of Ca10−xKx(PO4)6F(2−2x)(OH)x with 0 ≤ x ≤ 1 synthesized by the wet precipitation method, were found to be single-phase apatites crystallizing in the hexagonal P63/m space group. The structural parameters, as well as the crystallite sizes, increased accordingly to the amount of added dopant-ions. The thermal behavior of these compounds, studied within the temperature range 500–1200 °C, indicated a partial decomposition of the apatitic phase and its transformation to tricalcium phosphate β-Ca3(PO4)2 at temperatures exceeding 750 °C. A relative density of the sintered samples achieved the highest value with x = 0.25 and reached about 95% after sintering at 1050 °C for 1 h. The microstructures of the sintered samples were of a trans-granular aspect and experienced an increase in the radius of their pores as x increased. The prepared bioceramic materials were mechanically characterized by means of Young’s modulus, flexural strength and fracture toughness measurements. The overall trend of these parameters evolved comparably to the relative density, and the maximum values obtained for x = 0.25 were measured to be 96 MPa, 47 MPa and 1.14 MPa·m1/2, respectively. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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18 pages, 6690 KiB  
Article
Development of Iron-Doped Hydroxyapatite Coatings
by Daniela Predoi, Simona Liliana Iconaru, Steluta Carmen Ciobanu, Silviu-Adrian Predoi, Nicolas Buton, Christelle Megier and Mircea Beuran
Coatings 2021, 11(2), 186; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11020186 - 05 Feb 2021
Cited by 24 | Viewed by 2968
Abstract
It is known that iron is found as a trace element in bone tissue, the main inorganic constituent of which is hydroxyapatite. Therefore, iron-doped hydroxyapatite (HApFe) materials could be new alternatives for many biomedical applications. A facile dip coating process was used to [...] Read more.
It is known that iron is found as a trace element in bone tissue, the main inorganic constituent of which is hydroxyapatite. Therefore, iron-doped hydroxyapatite (HApFe) materials could be new alternatives for many biomedical applications. A facile dip coating process was used to elaborate the iron-doped hydroxyapatite (HApFe) nanocomposite coatings. The HApFe suspension used to prepare the coatings was achieved using a co-precipitation method, which was adapted in the laboratory. The quality of the HApFe suspension was assessed through dynamic light scattering (DLS), ultrasonic measurements, and zeta potential values. The hydroxyapatite XRD patterns were observed in the HApFe nanocomposite with no significant shifting of peak positions, thus suggesting that the incorporation of iron did not significantly modify the hydroxyapatite structure. The morphology of the HApFe nanoparticles was evaluated using transmission electron microscopy (TEM). Scanning electron microscopy (SEM) was used in order to investigate the morphologies of HApFe particles and coatings, while their chemical compositions were assessed using energy-dispersive X-ray spectroscopy (EDS). The SEM results suggested that the HApFe consists mainly of spherical nanometric particles and that the surfaces of the coatings are continuous and homogeneous. Additionally, the EDS spectra highlighted the purity of the samples and confirmed the presence of calcium, phosphorous, and iron in the analyzed sample. The in vitro cytotoxicity of the HApFe suspensions and coatings was evidenced using osteoblast cells. The MTT assay showed that both the HApFe suspensions and coatings exhibited biocompatible properties. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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25 pages, 18865 KiB  
Article
Multi-Level Evaluation of UV Action upon Vitamin D Enhanced, Silver Doped Hydroxyapatite Thin Films Deposited on Titanium Substrate
by Catalin Constantin Negrila, Daniela Predoi, Rodica V. Ghita, Simona Liliana Iconaru, Steluta Carmen Ciobanu, Mirela Manea, Monica Luminita Badea, Adrian Costescu, Roxana Trusca, Gabriel Predoi, George A. Stanciu, Radu Hristu, Laura Denisa Dragu, Coralia Bleotu, Andreea Groza, Ioana Cristina Marinas and Mariana Carmen Chifiriuc
Coatings 2021, 11(2), 120; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11020120 - 21 Jan 2021
Cited by 3 | Viewed by 2101
Abstract
Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is an important bioactive material for bone tissue reconstruction, due to its highly thermodynamic stability at a physiological pH without bio-resorption. In the present study, the Ag:HAp and the corresponding Ag:HAp + D3 [...] Read more.
Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is an important bioactive material for bone tissue reconstruction, due to its highly thermodynamic stability at a physiological pH without bio-resorption. In the present study, the Ag:HAp and the corresponding Ag:HAp + D3 thin films (~200 nm) coating were obtained by vacuum deposition method on Ti substrate. The obtained samples were exposed to different UV irradiation times, in order to investigate the UV light action upon thin films, before considering this method for the thin film’s decontamination. The effects of UV irradiation upon Ag:Hap + D3 are presented for the first time in the literature, marking a turning point for understanding the effect of UV light on composite biomaterial thin films. The UV irradiation induced an increase in the initial stages of surface roughness of Ag:HAp thin film, correlated with the modifications of XPS and FTIR signals. The characteristics of thin films measured by AFM (RMS) analysis corroborated with XPS and FTIR investigation highlighted a process of recovery of the thin film’s properties (e.g., RMS), suggesting a possible adaptation to UV irradiation. This process has been a stage to a more complicated UVA rapid degradation process. The antifungal assays demonstrated that all the investigated samples exhibited antifungal properties. Moreover, the cytotoxicity assays revealed that the HeLa cells morphology did not show any alterations after 24 h of incubation with the Ag:HAp and Ag:HAp + D3 thin films. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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18 pages, 7031 KiB  
Article
Antimicrobial Properties of Samarium Doped Hydroxyapatite Suspensions and Coatings
by Simona Liliana Iconaru, Andreea Groza, Sofia Gaiaschi, Krzysztof Rokosz, Steinar Raaen, Steluta Carmen Ciobanu, Patrick Chapon and Daniela Predoi
Coatings 2020, 10(11), 1124; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings10111124 - 20 Nov 2020
Cited by 19 | Viewed by 3058
Abstract
Post-implant infections are a major health problem, and it is well-known that treating them with conventional drugs is accompanied by many disadvantages. The development of new biomaterials with enhanced antimicrobial properties are of major interest for the scientific world. The aim of this [...] Read more.
Post-implant infections are a major health problem, and it is well-known that treating them with conventional drugs is accompanied by many disadvantages. The development of new biomaterials with enhanced antimicrobial properties are of major interest for the scientific world. The aim of this study was to synthesize and characterize hydroxyapatite doped with Samarium (Ca10−xSmx(PO4)6(OH)2, xSm = 0.05, 5Sm-HAp) suspensions, pellets and coatings. The 5Sm-HAp coatings on Si substrates were obtained by rf magnetron sputtering technique. The different techniques such as ultrasound measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Glow Discharge Optical Emission Spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to examine the obtained coatings. The results showed that the doped Sm ions entered the structure of hydroxyapatite successfully and Sm ions was uniformly doped onto the surface of the support. The depth profile curves of Ca, P, O, H, Ce and Si elements exhibit their presence from a surface to substrate interface as function of sputtering time. XPS analysis indicated as calcium-phosphate structures enriched in Sm3+ ions. Furthermore, the antimicrobial properties of the 5Sm-HAp suspensions, targets and coatings were assessed against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231. The results of the antimicrobial assays highlighted that that the samples presented a strong antimicrobial activity against the tested microbial strains. The results showed that the coatings after 48 h of incubation inhibited the growth of all tested microbial strains under the value of 0.6 Log CFU/mL. This study shows that the 5Sm-HAp samples are good candidates for the development of new antimicrobial agents. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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17 pages, 7351 KiB  
Article
Development of Cerium-Doped Hydroxyapatite Coatings with Antimicrobial Properties for Biomedical Applications
by Daniela Predoi, Simona Liliana Iconaru, Mihai Valentin Predoi, Andreea Groza, Sofia Gaiaschi, Krzysztof Rokosz, Steinar Raaen, Catalin Constantin Negrila, Alina-Mihaela Prodan, Adrian Costescu, Monica Luminita Badea and Patrick Chapon
Coatings 2020, 10(6), 516; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings10060516 - 28 May 2020
Cited by 29 | Viewed by 3740
Abstract
Antibacterial cerium-doped hydroxyapatite (Ce-HAp) layers have been researched sparingly in recent years. The Ce-HAp powder, Ca10−xCex(PO4)6(OH)2 with xCe = 0.05, was obtained by an adapted chemical co-precipitation method at room temperature. The target [...] Read more.
Antibacterial cerium-doped hydroxyapatite (Ce-HAp) layers have been researched sparingly in recent years. The Ce-HAp powder, Ca10−xCex(PO4)6(OH)2 with xCe = 0.05, was obtained by an adapted chemical co-precipitation method at room temperature. The target was prepared using the Ce-HAp (xCe = 0.05) powder sintered in air at 600 °C. The coatings on the Ti substrate were generated in plasma using a radio frequency (RF) magnetron sputtering discharge in an Ar gas flow in a single run. To collect the most complete information regarding the antimicrobial activity of cerium-doped hydroxyapatite with xCe = 0.05, (5Ce-HAp), antimicrobial studies were carried out both on the final suspensions and on the coated surfaces. The target was tested using ultrasound measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), glow-discharge optical emission spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The present study exhibited for the first time results of the homogeneous coatings of hydroxyapatite doped with cerium using a radio frequency magnetron sputtering technique. In addition, this study highlighted for the first time the stability of the cerium-doped hydroxyapatite gels used in the creation of the coating. Ultrasound measurements on the concentrated suspension of 5Ce-HAp showed a good stability compared to double distilled, water which was chosen as the reference fluid. Particles with spherical shape were observed by both TEM and SEM analysis. The broadening of the IR bands in the IR spectrum of the 5Ce-HAp film in comparison with the IR spectrum of the precursor target indicate the formation of interlinked bonds into the layer bulk. XPS analysis revealed that the mixture of Ce3+ and Ce4+ ions in the hydroxyapatite (HAp) structure of the coatings could be due to the deposition process. The surface of 5Ce-HAp coatings was homogenous with particles having a spherical shape. A uniform distribution of all the constituent elements on the surface the 5Ce-HAp layer was revealed. The antimicrobial assays proved that both 5Ce-HAp suspensions and 5Ce-HAp coatings effectively inhibited the development of colony forming units (CFU) for all the tested microbial strains. Moreover, the antimicrobial assays emphasized that the 5Ce-HAp suspensions had a biocide effect against Escherichia coli (E. coli) and Candida albicans (C. albicans) microbial strains after 72 h of incubation. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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23 pages, 10024 KiB  
Article
Obtaining and Characterizing Thin Layers of Magnesium Doped Hydroxyapatite by Dip Coating Procedure
by Daniela Predoi, Simona Liliana Iconaru, Mihai Valentin Predoi, Mikael Motelica-Heino, Nicolas Buton and Christelle Megier
Coatings 2020, 10(6), 510; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings10060510 - 27 May 2020
Cited by 27 | Viewed by 2773
Abstract
A simple dip coating procedure was used to prepare the magnesium doped hydroxyapatite coatings. An adapted co-precipitation method was used in order to obtain a Ca25−xMgx(PO4)6(OH)2, 25MgHAp (xMg = 0.25) [...] Read more.
A simple dip coating procedure was used to prepare the magnesium doped hydroxyapatite coatings. An adapted co-precipitation method was used in order to obtain a Ca25−xMgx(PO4)6(OH)2, 25MgHAp (xMg = 0.25) suspension for preparing the coatings. The stabilities of 25MgHAp suspensions were evaluated using ultrasound measurements, zeta potential (ZP), and dynamic light scattering (DLS). Using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) information at nanometric resolution regarding the shape and distribution of the 25MgHAp particles in suspension was obtained. The surfaces of obtained layers were evaluated using SEM and atomic force microscopy (AFM) analysis. The antimicrobial evaluation of 25MgHAp suspensions and coatings on various bacterial strains and fungus were realized. The present study presents important results regarding the physico-chemical and antimicrobial studies of the magnesium doped hydroxyapatite suspensions, as well as the coatings. The studies have shown that magnesium doped hydroxyapatite suspensions prepared with xMg = 0.25 presented a good stability and relevant antimicrobial properties. The coatings made using 25MgHAp suspension were homogeneous and showed remarkable antimicrobial properties. Also, it was observed that the layer realized has antimicrobial properties very close to those of the suspension. Both samples of the 25MgHAp suspensions and coatings have very good biocompatible properties. Full article
(This article belongs to the Special Issue Hydroxyapatite Based Coatings for Biomedical Applications)
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