GPTMS Content Research Articles

Fabrication of Noncytotoxic Functional Siloxane-Coated Bacterial Cellulose Nanocrystals

Bacterial cellulose nanocrystals (BCNC) stand out as versatile biocolloidal building blocks for materials that are high-performance, owing to their inherently high crystallinity and specific modulus and surface area, and sustainable, as BCNC are both biobased and biodegradable. BCNC materials are also promising for their multifunctionality because of their huge potential to undergo physical and/or chemical surface modification. This is particularly appealing for biomedical applications thanks to the biocompatibility, high purity, and low toxicity of BCNC. We report on films based on surface-modified BCNC with varying contents of 3-glycidyloxypropyltrimethoxysilane (GPTMS) or 3-aminopropyltriethoxysilane (APTS). Importantly, these highly pure and crystalline needle-shaped BCNC were isolated from scraps generated at industrial operations when shaping bacterial cellulose membranes into wound dressings. The films were extensively characterized as far as their structural characteristics, with emphasis on the major features targeting at biological applications. Compared with pristine BCNC, the films performed better from the thermal stability standpoint and maintained the noncytotoxicity against nontransforming fibroblasts. The latter claim was independent of GPTMS content, but dose-dependent for APTS and valid for films containing up to 30% of this coupling agent. Altogether, this contribution expands the wingspan of nanocellulose-based materials in biomedical applications while mitigating the waste of natural resources by upcycling an industrial byproduct, falling within the circular bioeconomy framework.

Evaluation of anti-corrosive properties of epoxidized rubber and siloxane hybrid coatings

ABSTRACT Elastomeric hybrid films were produced from the epoxidized nitrile rubber with the 3-glycidyloxypropyl-trimethoxysilane (GPTMS) inorganic precursor by the sol–gel process. There were no significant changes in the thermal properties of hybrids in relation to pure epoxidized rubber. The degree of swelling decreased while the mechanical resistance increased with increasing GPTMS content. The sol–gel process was performed on metal plates, which were then subjected to a corrosion process by immersion in NaCl solution and evaluated by Electrochemical Impedance Spectroscopy. The resistance and the capacitance values of the nitrile rubber coating are 8.8 × 103 Ω cm2 and 1.9 × 10−4 F cm−2, whereas for the hybrid with 38 phr of GPTMS the values are 2.3 × 106 Ω cm2 and 15.8 × 10−10 F cm−2, respectively, indicating higher cross-link density, less electrolyte absorption, less degradation, greater adherence to the metal surface via silane groups and, consequently, better corrosion protection achieved by the hybrid films.

The influence of 3‐glycidyloxypropyl trimethoxysilane on the rheological and in‐vitro behavior of injectable composites containing64Sbioactive glass, chitosan, and gelatin

AbstractThe effect of cross‐linker 3‐glycidyloxypropyl trimethoxysilane (GPTMS) on the injectability, bioactivity, rheology, washout resistance, and cellular behavior of bio‐nano composite pastes containing a sol–gel derived bioactive glass (BG), chitosan (Cn), and gelatin (Gel), were studied. The results indicated that the structural integrity of the samples in the stimulated body fluid (SBF) was improved from 80% to 90% with the increase in the GPTMS content. In addition, the viscosity and injectability of the paste were affected, so that the later changed from 96% to 73% and the former changed from 132 × 103to 210 × 103 Pa.s, with addition of 20 wt% GPTMS. Furthermore, the bioactivity of the pastes was improved with the use of GPTMS. No toxicity was observed in the cellular studies of the GPTMS containing paste after 7 days, and the cells kept their shape and were attached firmly to the paste surface. The results of the present work showed that the use of GPTMS was beneficial in enhancing the properties of injectable paste.

Optical, mechanical and dielectric properties of sol-gel PMMA-GPTMS-ZrO2 hybrid thin films with variable GPTMS content

We report the synthesis, characterization, and dielectric gate application of organic-inorganic PMMA-GPTMS-ZrO2 hybrid films, where GPTMS (3-glycidyloxypropyl(trimethoxy)silane) is the coupling agent. Three hybrid films were deposited by sol-gel varying the GPTMS concentration in the precursor solution, and their properties were analyzed by UV-Vis, FTIR, TGA, AFM, FE-SEM, EDS, XPS, and nanoindentation. Their electrical properties were measured on MIM devices. The homogeneity and high optical transparency of the hybrid films bear out the achievement of cross-linked organic-inorganic phases. The optical, mechanical, and dielectric properties of the hybrid films depend on the amount of GPTMS in their composition. The refractive index, mechanical hardness, elastic modulus, and dielectric constant of the hybrid films varied in the ranges of 1.54-1.61, 2.2-2.7 GPa, 87-123 GPa, and 7.6-13.6, respectively, depending on the GPTMS amount. The hybrid films were applied as dielectric gate in TFTs with ZnO as the semiconductor exhibiting good performance at low operating voltages.

Chitosan-GPTMS-Silica Hybrid Mesoporous Aerogels for Bone Tissue Engineering.

This study introduces a new synthesis route for obtaining homogeneous chitosan (CS)-silica hybrid aerogels with CS contents up to 10 wt%, using 3-glycidoxypropyl trimethoxysilane (GPTMS) as coupling agent, for tissue engineering applications. Aerogels were obtained using the sol-gel process followed by CO2 supercritical drying, resulting in samples with bulk densities ranging from 0.17 g/cm3 to 0.38 g/cm3. The textural analysis by N2-physisorption revealed an interconnected mesopore network with decreasing specific surface areas (1230–700 m2/g) and pore sizes (11.1–8.7 nm) by increasing GPTMS content (2–4 molar ratio GPTMS:CS monomer). In addition, samples exhibited extremely fast swelling by spontaneous capillary imbibition in PBS solution, presenting swelling capacities from 1.75 to 3.75. The formation of a covalent crosslinked hybrid structure was suggested by FTIR and confirmed by an increase of four hundred fold or more in the compressive strength up to 96 MPa. Instead, samples synthesized without GPTMS fractured at only 0.10–0.26 MPa, revealing a week structure consisted in interpenetrated polymer networks. The aerogels presented bioactivity in simulated body fluid (SBF), as confirmed by the in vitro formation of hydroxyapatite (HAp) layer with crystal size of approximately 2 µm size in diameter. In vitro studies revealed also non cytotoxic effect on HOB® osteoblasts and also a mechanosensitive response. Additionally, control cells grown on glass developed scarce or no stress fibers, while cells grown on hybrid samples showed a significant (p < 0.05) increase in well-developed stress fibers and mature focal adhesion complexes.

Preparation and Characterization of pH Sensitive Chitosan/3-Glycidyloxypropyl Trimethoxysilane (GPTMS) Hydrogels by Sol-Gel Method.

pH responsive chitosan and 3-Glycidyloxypropyl trimethoxysilane (GPTMS) hydrogels were synthesized by the sol-gel crosslinking reaction. GPTMS was introduced to influence several behaviors of the chitosan hydrogels, such as the swelling ratio, mechanical properties, swelling thermodynamics, kinetics, and expansion mechanism. The functional groups of Chitosan/GPTMS hybrid hydrogels were verified by FT-IR spectrometer. Differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA) were used to analyzed the thermal behavior of water molecules, the expansion of thermodynamics, and the content of water molecules in the hydrogel. The results show that hydrogel consists of 50 wt.% GPTMS (CG50) and has good mechanical properties and sensitivity to pH response characteristics in the acidic/alkaline buffer solution. The increase of GPTMS content leads to the increase of hydrophobic groups in the hydrogel and causes the decrease of the overall water content and the freezing bond water content. When the hydrogels were immersed in acid solution, the interaction force parameter was smaller than that of DI-water and alkaline. It means that the interaction forces between hydrogel and water molecules are relatively strong. The swelling kinetics of hybrid hydrogels were investigated to inspect the swelling mechanism. The result is consistent with the Fisk’s diffusion mechanism, meaning that the rate of water penetration is adjustable. The biodegradable hydrogel (CG50) in this study has good environmental sensitivity and mechanical properties. It is suitable to be applied in the fields of drug release or biomedical technology.

Effect of Silane-Coupling Modification on the Performance of chitosan-poly vinyl Alcohol-Hybrid Scaffolds in Bone Tissue Engineering

Biocompatibility and biodegradability characteristics of some polymers make them an excellent candidate to fabricate porous scaffolds for tissue engineering applications. However, the scaffold mechanical properties and biodegradation rate are vital for bone tissue replacement applications, which can be improved using proper fabrication techniques and cross-linker. In this investigation, Chitosan-polyvinyl alcohol scaffolds were prepared by freeze-drying technique utilizing various weight ratios of 3-Glycidoxypropyl trimethoxysilane (GPTMS) as a bioactive inorganic crosslinker. SEM micrographs indicated interconnected porous structures of cross-linked scaffolds while the average diameter of pores increased as a function of cross-linker enhancement. FTIR analysis was performed to confirm interactions among organic and inorganic components. The mechanical strength test represented that increasing GPTMS content improves the compressive strength of samples. The absorption capacity of the scaffolds in the PBS solution exhibited a decrease in water uptake and biodegradation by increasing silane coupling agent concentration. The formation of needle-like apatite particles proved suitable bioactivity of cross-linked samples. Moreover, MTT assay and ALP expression showed an acceptable adhesion, spreading, proliferation, and differentiation of MG-63 cells on the silane-contained scaffolds. Obtained results warrant further preclinical and clinical evaluations.

Pectin-GPTMS-Based Biomaterial: toward a Sustainable Bioprinting of 3D scaffolds for Tissue Engineering Application.

Developing green and nontoxic biomaterials, derived from renewable sources and processable through 3D bioprinting technologies, is an emerging challenge of sustainable tissue engineering. Here, pectin from citrus peels was cross-linked for the first time with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) through a one-pot procedure. Freeze-dried porous pectin sponges, with tunable properties in terms of porosity, water uptake, and compressive modulus, were obtained by controlling GPTMS content. Cell experiments showed that GPTMS did not affect the cytocompatibility of pectin. The addition of GPTMS improved the printability of pectin due to an increase of viscosity and yield stress. Three-dimensional woodpile and complex anatomical-shaped scaffolds with interconnected micro- and macropores were, therefore, bioprinted without the use of any additional support material. These results show the great potential of using pectin cross-linked with GPTMS as biomaterial ink to fabricate patient-specific scaffolds, which could be used to promote tissue regeneration in vivo.

Novel bioactive porous starch-siloxane matrix for bone regeneration: Physicochemical, mechanical, and in vitro properties.

So far, many studies have focused on biodegradable scaffolds for tissue engineering purposes. Herein, a starch-based biodegradable scaffold was fabricated by the freeze-drying method and cross-linked using a different concentration of 3-glycidoxypropyl-trimethoxysilane (GPTMS). Field emission scanning electron microscopy (FE-SEM) micrographs indicated an interconnected porous microstructure in which the porosity decreased as a function of starch and GPTMS content. Increasing the mechanical stability and decreasing absorption capacity and biodegradation ratio affected by the higher concentration of cross-linker and the changes in structure as a function of cross-linker enhancement. Moreover, the mineralization of hybrid structures in simulated body fluid was proved by FE-SEM image and X-ray diffraction analysis. Results indicated the more GPTMS in scaffolds led to more hydroxyapatite formation. The ability of the growth and proliferation of bone marrow mesenchyme stem cells on the constructs confirmed the ability of scaffolds for bone tissue engineering applications.

Fabrication of Biocompatible, Functional, and Transparent Hybrid Films Based on Silk Fibroin and Epoxy Silane for Biophotonics.

In this work we explored the fabrication of flexible and transparent hybrids of silk fibroin (SF) and epoxy-modified siloxane for photonic applications. It is well-known that regenerated SF solutions can form free-standing films with high transparency. Although SF has a restricted number of chemically reactive side groups, the main issues of as-cast pristine SF films regard the high solubility into aqueous media, brittleness, and low thermal stability. The design of SF films with enhanced functionality but high transparency triggers new opportunities on a broader range of applications in biophotonics. Here we present a simple, functional, yet remarkably versatile hybrid material derived from silica sol-gel process based on SF protein and (3-glycidyloxypropyl)trimethoxysilane (GPTMS), an organically modified silicon-alkoxide owning a reactive terminal epoxy group. Specifically, we investigated the effect of the addition of GPTMS into SF solutions on the processability, morphology, crystallinity, and mechanical and optical properties of the resulting hybrid films. Highly transparent (ca. 90%) and flexible free-standing hybrid films were achieved. Cell viability assays revealed that the hybrid films are noncytotoxic to rat osteoblast cells even at high GPTMS content (up to 70 wt %). The hybrid films showed enhanced thermal stability and were rich in organic (epoxy) and inorganic (silanol) functional groups according to the content of GPTMS. We also evaluated the successful preparation of high-quality optical red emissive SF hybrid films by loading YVO4:Eu3+ nanoparticles at low concentration (<5 wt %). A meaningful description of the hybrid film structure is reported from the combination of scanning electron and atomic force microscopies, vibrational spectroscopy, solid-state NMR, and X-ray diffraction analyses.

Effect of inorganic/organic ratio and chemical coupling on the performance of porous silica/chitosan hybrid scaffolds

Inorganic/organic hybrid scaffolds have great potential for tissue engineering applications due to controllable mechanical properties and tailorable biodegradation. Here, silica/chitosan hybrid scaffolds were fabricated through the sol-gel method with a freeze drying process. 3-Glycidoxypropyl trimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) were used as the covalent inorganic/organic coupling agent and the separate inorganic source, respectively. Hybrid scaffolds with various inorganic/organic weight ratios (I/Os) and molar ratios of chitosan and GPTMS (GCs) were examined and compared in this study. FTIR showed that higher GPTMS content resulted in the increased covalent cross-linking of the chitosan and the silica network in hybrids. Compression testing indicated that increasing the GPTMS content greatly improved the compressive strength of scaffold. LIVE/DEAD assay showed that enhanced cytocompatibility was obtained as the silica content increased. Therefore, the results confirmed that the two parameters I/O and GC can largely influence the scaffold performance, which can be used to tailor the hybrid properties.

Preparation and characterization of polyfluoroaniline/organosiloxane hybrid films

Polyfluoroaniline (PFANI)/organosiloxane hybrid films were directly prepared from PFANI emulsions and γ-glycidoxypropyltrimethoxysilane (GPTMS) through a sol–gel method. The influence of GPTMS/FANI molar ratios on the morphology and properties of PFANI/GPTMS hybrid films was characterized by fourier-transform infrared, scanning electron microscopy, thermo gravimetric, contact angle measurement and potentiodynamic polarization analysis. It was found that the hybrid films are highly water repellent. In addition, increasing the GPTMS content could significantly improve the thermal behavior and corrosion resistant ability of the hybrid films. However, the water repellency decreases slowly as the GPTMS/FANI molar ratio increases.

Mechanical property evaluation of corrosion protection sol–gel nanocomposite coatings

Organic–inorganic nanocomposite coatings were prepared from tetraethylorthosilicate and 3-glycidoxypropyltrimethoxysilane (GPTMS) by sol–gel method. These ormosil films were deposited by dip coating on aluminium alloy 5083. The effect of the concentration of GPTMS on the adhesion, mechanical and corrosion performance of coated samples was investigated. Adhesive strength of sol–gel coatings to the substrate was evaluated using pull-off and tape tests. Bending, impact resistance, pencil scratch and potentiodynamic polarisation tests were employed to characterise mechanical and corrosion performance of coated substrates with different GPTMS content. The chemical composition and the microstructure of the hybrid films were studied by attenuated total reflectance–Fourier transform infrared spectroscopy and field emission scanning electron microscopy respectively. The results indicate that the hybrid films had good mechanical properties, and the coating with minimum organic content had minimum corrosion current density, but the corrosion current density did not have any specific trend with an increased organic content.

Fabrication of novel collagen-silica hybrid membranes with tailored biodegradation and strong cell contact guidance ability

The fabrication of novel collagen-silica hybrid membranes with tailored biodegradation and strong cell contact guidance ability is reported in the present study. Collagen-silica hybrids were first synthesized by reacting 3-glycidoxypropyltrimethoxysilane (GPTMS), which functioned as both the cross-linker and the silica source, with acid-soluble type I porcine collagen monomers. Subsequently, they were coated and dried on the surface of polydimethylsiloxane (PDMS) chips with either flat or microgroove surfaces to produce the corresponding collagen-silica hybrid membrane with a flat or microgroove surface. Scanning electron microscopy images showed that membranes formed on flat PDMS chips exhibited smooth and dense surfaces, while those formed on microgrooved PDMS chips exhibited typical microgroove surfaces with a 10 μm groove width, 8 μm ridge width, and 0.5 μm depth. Despite the difference in surface topography, both flat and microgrooved collagen-silica membranes exhibited stronger resistance against collagenase enzyme than the original collagen membrane due to the presence of silica, and the biodegradation rate of the samples was controllable through adjustment of the GPTMS content. Upon incubation with C2C12 skeletal myoblasts, both samples supported cell attachment, proliferation, and differentiation, suggesting good biocompatibility. However, a significant difference in cell morphology was observed. Cells on the flat membranes were randomly distributed, while those on the microgrooved samples were highly aligned and elongated, indicating that the microgrooved membranes exhibit much stronger cell contact guidance ability. The immunochemical assay showed that both flat and microgrooved samples supported the differentiation of C2C12 myoblasts to form multinucleated myotubes; however, the presence of the microgrooved surface topography significantly enhanced cell differentiation.

Biodegradable Chitosan-Silicate Porous Hybrids for Drug Delivery

Porous chitosan-silicate hybrids were prepared by freeze-drying the precursor sol solutions synthesized from chitosan and 3-glycidoxypropyltrimethoxysilane (GPTMS). Degradability of and the release of cytochrome C in to phosphate buffer saline solution (PBS) were examined as a function of the GPTMS content. The hybrids were less degradable with larger GPTMS contents, and the cytochrome C release profile was so controllable as to give either burst release or slow one due to the GPTMS content. Thus, the present porous chitosan-silicate hybrids were considered applicable to drug delivery systems.

Synthesis and cytocompatibility of porous chitosan–silicate hybrids for tissue engineering scaffold application

Abstract Chitosan–silicate hybrids with 3D porous structures were prepared with freeze-drying precursor solutions derived from chitosan and γ-glycidoxypropyltrimethoxysilane (GPTMS). They were formed easily in any shape, such as sheets, pellets, disks, granules, and even roll-cakes. The pore size was strongly dependent on the freezing temperature: lower freezing temperature resulted smaller pores, about 110 μm for the hybrids frozen at −20 °C, and about 50 μm for those at −85 °C. The pore size was little dependent on the GPTMS content. In contrast, the GPTMS content affected porosity a littlie: ∼80% for chitosan, and ∼90% for the GPTMS-containing hybrids. Thus, their porous microstructure was controllable due to the freezing temperature and composition. MG63 osteoblastic cells were cultured up to 7 days on the porous hybrids. The cells adhered on the pore walls, proliferated, and migrated deep into the pore structure. It was thus concluded that the present chitosan–silicate hybrids were promising for tissue engineering scaffold applications.

Hybrid Organic−Inorganic Membrane: Solving the Tradeoff between Permeability and Selectivity

To solve the tradeoff between permeability and selectivity of polymeric membranes, organic−inorganic hybrid membranes composed of poly(vinyl alcohol) (PVA) and γ-glycidyloxypropyltrimethoxysilane (GPTMS) were prepared by an in situ sol−gel approach for pervaporative separation of benzene/ cyclohexane mixtures. The structure of PVA-GPTMS hybrid membranes was characterized with FTIR, 29Si NMR, SEM, TEM, and XRD. Energy-dispersive X-ray Si-mapping analysis demonstrated homogeneous dispersion of silica in the PVA matrix. Compared with pure PVA membranes, the hybrid membranes exhibited high thermal stability and lower Tg, and in particular improved pervaporation properties. Permeation flux increased from 20.3 g/(m2 h) for pure PVA membrane to 137.1 g/(m2 h) for PVA-GPTMS hybrid membrane with 28 wt % GPTMS content, and separation factor increased from 9.6 to 46.9 correspondingly. The pervaporation results of PVA-GPTMS hybrid membranes are all above the upper bound tradeoff curve (Lue, S. J.; Peng, S. H. J. Membr. Sci. 2003, 222, 203), while that of pure PVA membrane is obviously below the curve. Positron annihilation lifetime spectroscopy (PALS) was employed to elucidate the enhancement of permeation flux in polymer-based pervaporation membranes, and a size-selective mechanism was proposed to explain the enhancement of the separation factor.

Phase structure and mechanical and adhesion properties of epoxy/silica hybrids

Organic/inorganic hybrids containing 4– to 19.8 wt% of silica were synthesized from an epoxy resin diglycidyl ether of bisphenol-A (DGEBA) and a γ-glycidoxypropyltrimethoxysilane (GPTMS) or a tetramethylorthosilicate (TMOS) by utilizing a sol/gel process. In the DGEBA/GPTMS hybrids, the storage modulus in the rubbery region increased and the peak area of the tan δ curves in the glass transition region decreased, respectively, with the hybrization of small amounts of silica. This may result from the suppression of the epoxy network moiety with the incorporation of the silica network. Observation using transmission electron microscopy (TEM) revealed that the silica networks are uniformity dispersed in the hybrids. Furthermore, the hybrids with GPTMS showed a very high adhesion strength for the silicone rubber. Results from the X-ray microanalysis show that the silica networks are concentrated in the interfacial area of the adhesive joints with silicone rubber. In the swelling test of silicone rubber with the epoxy resin containing GPTMS, the degree of swelling increased with increasing GPTMS content. The high adhesion strength observed in the DGEBA/GPTMS hybrids was caused by the immersion of the adhesives into the surface layer of the silicone rubber substrate, which was attributed to the good affinity between GPTMS and the silicone rubber.