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Functionalized Silica Materials: Preparation and Applications

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (20 March 2023) | Viewed by 11342

Image courtesy of Dr. Ana-Maria Putz

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Dr. Ana-Maria Lacrămă

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“Coriolan Dragulescu” Institute of Chemistry, Romanian Academy, 24 Mihai Viteazu Bvd., 300223 Timisoara, Romania
Interests: functionalized silica materials; iron oxide silica nanocomposites; adsorption; drug loading; ionic liquids
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Special Issue Information

Dear Colleagues,

This Special Issue is intended to present studies on the preparation and characterization of controlled functionalized porous materials with tailored properties that can be used in different applications. The functionalization of the porous silica materials has been used as a method in view of tuning the physical and chemical properties to be applied such as drug carriers, gas storage materials, water pollutants adsorbents, or as asphalt modifier. The present Special Issue aims to gather some of the current challenging research explorations in the use of different functional groups, the presence of organic groups within the pores or of the amount of a certain functional group which will be attached at the material surface by one or another functionalization procedure, and in how all these separate or combined effects will merge together to promote the resulting material for a certain application. The topics of interest include but are not limited to: preparation of functionalized porous materials via co-condensation or post grafting methods; structural and morphological characterization of these materials with tailored properties; functionalized silica materials for hydrogen, methane, or carbon dioxide storage; functionalized porous silica materials as drug carriers; functionalized mesoporous silica materials used for removal of dyes, heavy metals, or other pollutants from waste water; functionalized silica materials used as an asphalt modifier.

Dr. Ana-Maria Putz
Guest Editor

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Keywords

functionalized silica materials
co-condensation
post-grafting
drug loading
gas adsorption
pollutant removal

Published Papers (5 papers)

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Research

15 pages, 8515 KiB

Open AccessArticle

Amino Surface Modification and Fluorescent Labelling of Porous Hollow Organosilica Particles: Optimization and Characterization

by Mohammed A. Al-Khafaji, Anikó Gaál, Bálint Jezsó, Judith Mihály and Zoltán Varga

Materials 2022, 15(7), 2696; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15072696 - 06 Apr 2022

Cited by 2 | Viewed by 2151

Abstract

Surface modification of silica nanoparticles with organic functional groups while maintaining colloidal stability remains a synthetic challenge. This work aimed to prepare highly dispersed porous hollow organosilica particles (pHOPs) with amino surface modification. The amino-surface modification of pHOPs was carried out with 3-aminopropyl(diethoxy)methylsilane (APDEMS) under various reaction parameters, and the optimal pHOP-NH₂ sample was selected and labelled with fluorescein isothiocyanate (FITC) to achieve fluorescent pHOPs (F-HOPs). The prepared pHOPs were thoroughly characterized by transmission electron microscopy, dynamic light scattering, FT-IR, UV-Vis and fluorescence spectroscopies, and microfluidic resistive pulse sensing. The optimal amino surface modification of pHOPs with APDEMS was at pH 10.2, at 60 °C temperature with 10 min reaction time. The positive Zeta potential of pHOP-NH₂ in an acidic environment and the appearance of vibrations characteristic to the surface amino groups on the FT-IR spectra prove the successful surface modification. A red-shift in the absorbance spectrum and the appearance of bands characteristic to secondary amines in the FTIR spectrum of F-HOP confirmed the covalent attachment of FITC to pHOP-NH₂. This study provides a step-by-step synthetic optimization and characterization of fluorescently labelled organosilica particles to enhance their optical properties and extend their applications. Full article

(This article belongs to the Special Issue Functionalized Silica Materials: Preparation and Applications)

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16 pages, 3643 KiB

Open AccessArticle

APTES-Modified SBA-15 as a Non-Toxic Carrier for Phenylbutazone

by Adrianna Dadej, Aneta Woźniak-Braszak, Paweł Bilski, Hanna Piotrowska-Kempisty, Małgorzata Józkowiak, Maciej Stawny, Daniela Dadej, Michał Mrotek and Anna Jelińska

Materials 2022, 15(3), 946; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030946 - 26 Jan 2022

Cited by 7 | Viewed by 2308

Abstract

Improvement of the bioavailability of poorly soluble medicinal substances is currently one of the major challenges for pharmaceutical industry. Enhancing the dissolution rate of those drugs using novel methods allows to increase their bioavailability. In recent years, silica-based mesoporous materials have been proposed as drug delivery systems that augment the dissolution rate. The aim of this study was to analyse the influence of phenylbutazone adsorption on SBA-15 on its dissolution rate. Moreover, we examined the cytotoxicity of the analyzed silica. The material was characterized by SEM, TEM, DSC, ¹H-NMR, XRD, and FT-IR. The phenylbutazone did not adsorb on unmodified SBA-15, while the adsorption on APTES-modified SBA-15 resulted in 50.43 mg/g of loaded phenylbutazone. Phenylbutazone adsorbed on the APTES-modified SBA-15 was then released in the hydrochloric acidic medium (pH 1.2) and phosphate buffer (pH 7.4) and compared to the dissolution rate of the crystalline phenylbutazone. The release profiles of the amorphous form of adsorbed phenylbutazone are constant in different pH, while the dissolution rate of the crystalline phenylbutazone depends on the pH. The cytotoxicity assays were performed using the Caco-2 cell line. Our results indicate that the analyzed material ensured phenylbutazone adsorption in an amorphous state inside the mesopores and increased its dissolution rate in various pH levels. Furthermore, the cytotoxicity assay proved safety of studied material. Our study demonstrated that APTES-modified SBA-15 can serve as a non-toxic drug carrier that improves the bioavailability of phenylbutazone. Full article

(This article belongs to the Special Issue Functionalized Silica Materials: Preparation and Applications)

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18 pages, 2217 KiB

Open AccessFeature PaperArticle

Butyl-Methyl-Pyridinium Tetrafluoroborate Confined in Mesoporous Silica Xerogels: Thermal Behaviour and Matrix-Template Interaction

by Ana-Maria Putz, László Almásy, Zsolt Endre Horváth and László Trif

Materials 2021, 14(17), 4918; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174918 - 29 Aug 2021

Cited by 2 | Viewed by 1943

Abstract

Organic-inorganic silica composites have been prepared via acid catalyzed sol-gel route using tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) as silica precursors and n-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF₄]) as co-solvent and pore template, by varying the content of the ionic liquid (IL). Morphology of the xerogels prepared using the ionic liquid templating agent were investigated using scanning electron microscopy and small angle neutron scattering (SANS). Thermal analysis has been used in order to evaluate the thermal and structural stability of the materials, in both nitrogen and synthetic air atmosphere. In nitrogen atmosphere, the IL decomposition took place in one step starting above 150 °C and completed in the 150–460 °C temperature interval. In synthetic air atmosphere, the IL decomposition produced two-step mass loss, mainly in the 170–430 °C temperature interval. The decomposition mechanism of the IL inside the silica matrix was studied by mass spectrometric evolved gas analysis (MSEGA). The measurements showed that the degradation of the IL’s longer side chain (butyl) starts at low temperature (above 150 °C) through a C-N bond cleavage, initiated by the nucleophilic attack of a fluorine ion. Full article

(This article belongs to the Special Issue Functionalized Silica Materials: Preparation and Applications)

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12 pages, 4792 KiB

Open AccessArticle

Synthesis of Zr-89-Labeled Folic Acid-Conjugated Silica (SiO₂) Microwire as a Tumor Diagnostics Carrier for Positron Emission Tomography

by Gun Gyun Kim, Hye Min Jang, Sung Bum Park, Jae-Seon So and Sang Wook Kim

Materials 2021, 14(12), 3226; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14123226 - 11 Jun 2021

Cited by 2 | Viewed by 1739

Abstract

This study evaluated the in vivo behavior and accumulation of silica particles in the form of wires, which were actively studied as drug carriers along with spheres, using positron emission tomography (PET). Wire-shaped silicon dioxide (SiO₂) was synthesized at micro-size, using anodic aluminum oxide (AAO), a template, and folic acid (FA), which specifically binds folate receptors (FR) which are overexpressed in many cancers, and which was bound to the wire’s surface to confirm its possible use as a cancer diagnostic agent. In addition, for evaluation using PET, the positron-emitting nuclide ⁸⁹Zr (t_1/2 = 3.3 days) was directly bonded to the hydroxyl group (-OH) on the particle surface. The diameter and shape of the synthesized silica microwires (SMWs) were confirmed using SEM and TEM, the chemical bonding of FA was confirmed through FT–IR and NMR, and the labeling of ⁸⁹Zr was measured by means of radio-thin-layer chromatography (TLC) measurement. Folic acid-conjugated SMWs (FA-SMWs) were found to have a low receptor-mediated uptake in cell internalization evaluation, but in PET studies, FA-SMWs stayed longer at the tumor site. In conclusion, we successfully synthesized a homogeneous silica microwire for drug delivery, we confirmed that the FA-conjugated sample remains at the tumor site for a relatively longer time, and we have reported the characteristic in vivo behavior of ⁸⁹Zr-FA-SMWs. Full article

(This article belongs to the Special Issue Functionalized Silica Materials: Preparation and Applications)

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19 pages, 1033 KiB

Open AccessArticle

Comparison of Structure and Adsorption Properties of Mesoporous Silica Functionalized with Aminopropyl Groups by the Co-Condensation and the Post Grafting Methods

by Ana-Maria Putz, Mihaela Ciopec, Adina Negrea, Oana Grad, Cătălin Ianăşi, Oleksandr I. Ivankov, Marija Milanović, Ivan Stijepović and László Almásy

Materials 2021, 14(3), 628; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14030628 - 29 Jan 2021

Cited by 23 | Viewed by 2173

Abstract

The adsorptive potential has been evaluated for the aminopropyl functionalized mesoporous silica materials obtained by co-condensation and post grafting methods. Nitrogen sorption, small angle neutron and X-ray scattering (SANS and SAXS) demonstrated high surface area and well-ordered hexagonal pore structure suitable for applications as adsorbents of metals from waste waters. A comparison of Cr(VI) adsorption properties of the materials prepared by different functionalization methods has been performed. The obtained results demonstrated the adsorption capacity due to the affinity of the chromium ions to the amino groups, and showed that co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyl triethoxysilane (APTES) resulted in higher metal sorption capacity of the materials compared to post-synthesis grafting of aminopropyl groups onto the mesoporous silica particles. Full article

(This article belongs to the Special Issue Functionalized Silica Materials: Preparation and Applications)

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