Search Results (17)

Silicon oxycarbide (SiOC), Ca- and Mg-modified silicon oxycarbide (SiCaOC and SiMgOC) were synthesized via sol–gel processing with subsequent pyrolysis in an inert gas atmosphere. The physicochemical structures of the materials were characterized by XRD, SEM, FTIR, and ²⁹Si MAS NMR. Biocompatibility and in vitro bioactivity were detected by MTT, cell adhesion assay, and simulated body fluid (SBF) immersion test. Mg and Ca were successfully doped into the network structure of SiOC, and the non-bridging oxygens (NBO) were formed. The hydroxycarbonate apatite (HCA) was formed on the modified SiOC surface after soaking in simulated body fluid (SBF) for 14 days, and the HCA generation rate of SiCaOC was higher than that of SiMgOC. Accompanying the increase of bioactivity, the network connectivity (NC) of the modified SiOC decreased from 6.05 of SiOC to 5.80 of SiCaOC and 5.60 of SiMgOC. However, structural characterization and biological experiments revealed the nonlinear relationship between the biological activity and NC of the modified SiOC materials. Full article

Background: This study explored the potential of MCM-48 mesoporous silica matrices as a drug delivery system for metformin hydrochloride, aimed at improving the therapeutic management of type 2 diabetes mellitus. The objectives included the synthesis and characterization of MCM-48, assessment of its drug loading capacity, analysis of drug release profiles under simulated physiological conditions, and the development of a multifractal dynamics-based theoretical framework to model and interpret the release kinetics. Methods: MCM-48 was synthesized using a sol–gel method and characterized by SEM-EDX, TEM, and nitrogen adsorption techniques. Drug loading was performed via adsorption at pH 12 using metformin hydrochloride solutions of 1 mg/mL (P-1) and 3 mg/mL (P-2). In vitro dissolution studies were conducted to evaluate the release profiles in simulated gastric and intestinal fluids. A multifractal dynamics model was developed to interpret the release kinetics. Results: SEM-EDX confirmed the uniform distribution of silicon and oxygen, while TEM images revealed a highly ordered cubic mesoporous structure. Nitrogen adsorption analyses showed a high specific surface area of 1325.96 m²/g for unloaded MCM-48, which decreased with drug loading, confirming efficient incorporation of metformin hydrochloride. The loading capacities were 59.788 mg/g (P-1) and 160.978 mg/g (P-2), with efficiencies of 99.65% and 89.43%, respectively. In vitro dissolution studies showed a biphasic release profile: an initial rapid release in gastric conditions followed by sustained release in intestinal fluids, achieving cumulative releases of 92.63% (P-1) and 82.64% (P-2) after 14 hours. The multifractal dynamics-based theoretical release curves closely matched the experimental data. Conclusions: MCM-48 mesoporous silica effectively enhanced metformin delivery, offering a controlled release profile well-suited for type 2 diabetes management. The multifractal theoretical framework provided valuable insights into drug release dynamics, contributing to the advancement of innovative drug delivery systems. Full article

Linear chlorinated phosphazene acid is prepared using PCl₅ and NH₄Cl as raw materials. Using hexaethylcyclotrisiloxane as the monomer, 1,1,3,3-tetramethyldisiloxane or 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as the end-capping agent, and linear chlorinated phosphazene acid as the catalyst, polydiethylsiloxane oligomers terminated with active Si-H or Si-CH=CH₂ groups have been prepared. Using hexaethylcyclotrisiloxane and 1,3,5,7-octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane or hexamethyldisiloxane as the end-capping agent, or using hexaethylcyclotrisiloxane and octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane as the end-capping agent, copolymers containing active Si-H bonds and dimethylsiloxane segments have been prepared under the catalysis of linear chlorinated phosphazene acid. The effects of catalyst dosage, reaction temperature, reaction time, end-capping agent, and polymerization monomer dosage on polymer yield and structure were investigated. Using 300 ppm of linear chlorinated phosphazene acid, oligomers and copolymers containing an active Si-H bond and diethylsiloxane segment were prepared under mild conditions. The molecular weight of the obtained polymers was close to their designed values, but their PDI values were small. The highest yield of α, ω-bisdimethylsiloxyl-terminated PDES oligomers reached 93%. Using oligomers and copolymers containing Si-H bonds and diethylsiloxane segments as crosslinkers, a silicone gel containing diethylsiloxane segments was prepared by hydrosilylation reaction. With the introduction of a diethylsiloxane segment, the glass transition temperature of the silicone gel decreased relative to that of the PDMS oligomer, but the temperature at 5% weight loss in nitrogen atmosphere decreased from 347 °C to 312 °C. The mechanism of the ring-opening polymerization of hexaethylcyclotrisiloxane catalyzed by linear chlorinated phosphazene acid is also discussed. Full article

The stability of slurries used for chemical mechanical polishing (CMP) is a crucial concern in industrial chip production, influencing both the quality and cost-effectiveness of polishing fluids. In silicon wafer polishing, the conventional use of commercial neutral silica sol combined with organic bases often leads to slurry instability. To address this issue, this study proposes organic amines—specifically ethanolamine (MEA), ethylenediamine (EDA), and tetramethylammonium hydroxide (TMAOH)—as catalysts for synthesizing alkaline silica sol tailored for silicon wafer polishing fluids. Sol–gel experiments and zeta potential measurements demonstrate the efficacy of this approach in enhancing the stability of silica sol. The quantitative analysis of surface hydroxyl groups reveals a direct correlation between enhanced stability and increased hydroxyl content. The application of the alkaline silica sol in silicon wafer polishing fluids improves polishing rates and enhances surface flatness according to atomic force microscopy (AFM). In addition, electrochemical experiments validate the capability of this polishing solution to mitigate corrosion on silicon wafer surfaces. These findings hold significant implications for the advancement of chemical mechanical polishing techniques in the field of integrated circuit fabrication. Full article

The use of plate-like materials to induce a percolation gel-like effect in electrorheological (ER) fluids is sparsely documented. Hence, we dispersed plate-like materials, namely natural mica, synthetic mica, and glass, as well as their pulverized particles, in various concentrations in silicone oil to form ER fluids. Subsequently, the rheological properties of the fluids were evaluated and compared to identify the threshold concentration for percolating a gel-like state. The shear stress and viscoelastic moduli under zero-field conditions confirmed that plate-like materials can be used to induce percolation gel-like effects in ER fluids. This is because of the high aspect ratio of the materials, which enhances their physical stability. In practical ER investigations, ER fluids based on synthetic mica (30.0 wt%) showed the highest yield stress of 516.2 Pa under an electric field strength of 3.0 kV mm⁻¹. This was attributed to the formation of large-cluster networks and additional polarization induced by the ions. This study provides a practical approach for developing a new type of gel-like ER fluid. Full article

Non-invasive scar management typically involves pressure therapy, hydration with silicones or moisturizers, and UV protection. Moisture loss from scars can lead to hypertrophic scar formation. Pressure therapy reduces blood flow, fibroblast activity, and transforming growth factor beta 1 (TGF-β1) release. This study examined various moisturizers and liquid silicone gel’s impact on microcirculation. 40 volunteers participated in a study where superficial abrasions were created to induce trans epidermal water loss (TEWL). Five moisturizers (TEDRA^®, TEDRA^® NT1, TEDRA^® NT3, Alhydran^®, Lipikar^®) and BAP Scar Care^® silicone gel were tested. TEWL, hydration, and blood flow were measured up to 4 h post-application. Results showed that silicone had the least impact on occlusion and hydration. Alhydran^® reduced blood flow the most, while Lipikar^® increased it the most. TEDRA^® NT1 had reduced flow compared to TEDRA^® and TEDRA^® NT3. All TEDRA^® products exhibited high hydration, and all but silicone showed good occlusion. Moisturizers influenced skin microcirculation, with some causing decrease, while others increased flow. However, the clinical impact on scarring remains unclear compared to the evident effects of hydration and occlusion. More research is necessary to study moisturizers alone and with pressure therapy on scars, along with potential adverse effects of increased microcirculation on scars. Full article

Silicone gel sheeting (SGS) and pressure garment therapy (PGT) are the International Clinical Recommendations on Scar Management’s (ICRSM) two principal non-invasive scar-healing procedures. This study created a new PGT-SGS composite (PGF-Biopor^®AB-based) via pre-strained screen printing. The Biopor^®AB hydrophobicity and nylon-hydrophilicity enabled self-pumping for PGT-SGS dual therapy and pressure-driven “warp insertions” mobility facilitates active-fluid transportation. Integrating both therapies in a single PGT-SGS composite achieved efficacy optimization, and the 3D channel structure allowed trauma-free active-fluid transport. The 3D channel topology enables smooth diffusional transport in active-fluid transport environments—and active “nylon absorbency” improved water uptake and enhanced permeability capabilities with sustainability achieved dynamic hydration. The sole use of PGF-Biopor^®AB composite in empirical trials verified dual therapy with trauma-free active-fluid transport with one-month efficacy, providing a new route for dual treatment and active scar management. Full article

Herein, the electrorheological (ER) performances of ER fluids were correlated with their colors to allow for the visual selection of the appropriate fluid for a specific application using naked eyes. A series of TiO₂-coated synthetic mica materials colored white, yellow, red, violet, blue, and green (referred to as color mica/TiO₂ materials) were fabricated via a facile sol–gel method. The colors were controlled by varying the thickness of the TiO₂ coating layer, as the coatings with different thicknesses exhibited different light interference effects. The synthesized color mica/TiO₂ materials were mixed with silicone oil to prepare colored ER fluids. The ER performances of the fluids decreased with increasing thickness of the TiO₂ layer in the order of white, yellow, red, violet, blue, and green materials. The ER performance of differently colored ER fluids was also affected by the electrical conductivity, dispersion stability, and concentrations of Na⁺ and Ca²⁺ ions. This pioneering study may provide a practical strategy for developing new ER fluid systems in future. Full article

Particle image velocimetry (PIV) is an optical and contactless measurement method for analyzing fluid blood dynamics in cardiovascular research. The main challenge to visualization investigated in the current research was matching the channel material’s index of refraction (IOR) to that of the fluid. Silicone is typically used as a channel material for these applications, so optical matching cannot be proven. This review considers hydrogel as a new PIV channel material for IOR matching. The advantages of hydrogels are their optical and mechanical properties. Hydrogels swell more than 90 vol% when hydrated in an aqueous solution and have an elastic behavior. This paper aimed to review single, double, and triple networks and nanocomposite hydrogels with suitable optical and mechanical properties to be used as PIV channel material, with a focus on cardiovascular applications. The properties are summarized in seven hydrogel groups: PAMPS, PAA, PVA, PAAm, PEG and PEO, PSA, and PNIPA. The reliability of the optical properties is related to low IORs, which allow higher light transmission. On the other hand, elastic modulus, tensile/compressive stress, and nominal tensile/compressive strain are higher for multiple-cross-linked and nanocomposite hydrogels than single mono-cross-linked gels. This review describes methods for measuring optical and mechanical properties, e.g., refractometry and mechanical testing. Full article

As a common industrial by-product, the spend fluid catalytic-cracking (SFCC) catalyst was used to prepare phosphate-based geopolymer for the first time. The structure and property of geopolymer with phosphoric acid concentration ranging from 6 to 14 mol/L was characterized by compressive strength measurements, X-ray powder diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and ²⁷Al and ²⁹Si nuclear magnetic resonance (NMR). A stable binder was formed with the compressive strength in the range of 9.8 to 30.2 MPa when the acid concentration was between 6 and 12 mol/L. The higher concentration of acid can promote the dissolution of raw materials and formation of geopolymer gels. The coordination of silicon and aluminum in geopolymer gel synthesized with the SFCC catalyst and metakaolin is similar. Compared with the geopolymer with metakaolin, which forms more Si-O-Al bonds, in the networks of geopolymer with the SFCC catalyst, more Si(Al)-O-P bonds were formed. These results indicate that the SFCC catalyst can be an excellent raw material for the synthesis of phosphate-based geopolymer. Full article

Both the chemistry and size of a material formed in vivo, or an implanted biomaterial, can alter the in vivo host response. Within the size range covered within this review, over 1 μm, chemistry is only important if the solid material is unstable and leeching small molecules. The macrophage activity and the resultant inflammatory response, however, are related to the size of the solid material. The premise of this review is that differences in size of the solid material, in different cases, can be the reason why there is some individual-to-individual variation in response. Specifically, the inflammatory response is enhanced when the size is between 1–50 μm. This will be looked at for three configurations: spherical particulate (silicone oil or gel from breast implants), elongated particulate (monosodium urate [MSU] crystals in gout or in kidney stones), and fibers (e.g., polyester used in fabric implants). These specific examples were selected because many still believe that the clinical outcome for each is controlled by the surface chemistry, when in fact it is the size. In each case, specific studies will be highlighted to either show a mechanism for creating different sizes and therefore a differential biological response (first three) or how changing the size and shape (diameter and spacing of fibers, in this example) can affect the response and can help explain the different responses to fabric implants found in vivo within the 1–50 μm size range. It was found that polyester fibers under 70 μm had a significant increase in macrophage response. Further, it was found that compounds found in synovial fluid could limit MSU crystal size. In addition, it was shown that plasma with low triglyceride levels emulsifies silicone oils to a greater extent than plasma with higher triglyceride levels. Therefore, in three cases it appears that differences in the inflammatory response between individuals and between different implants could be explained just by the size of the material formed or implanted. Full article

Silica/biopolymer hydrogel-based materials constitute very attractive platforms for various emerging biomedical applications, particularly for bone repair. The incorporation of calcium phosphates in the hybrid network allows for designing implants with interesting biological properties. Here, we introduce a synthesis procedure for obtaining silica–chitosan (CS)–tricalcium phosphate (TCP) xerogels, with CS nominal content varying from 4 to 40 wt.% and 10 to 20 wt.% TCP. Samples were obtained using the sol-gel process assisted with ultrasound probe, and the influence of ethanol or water as washing solvents on surface area, micro- and mesopore volume, and average pore size were examined in order to optimize their textural properties. Three washing solutions with different soaking conditions were tested: 1 or 7 days in absolute ethanol and 30 days in distilled water, resulting in E1, E7, and W30 washing series, respectively. Soaked samples were eventually dried by evaporative drying at air ambient pressure, and the formation of interpenetrated hybrid structures was suggested by Fourier transformed infrared (FTIR) spectroscopy. In addition the impact that both washing solvent and TCP content have on the biodegradation, in vitro bioactivity and osteoconduction of xerogels were explored. It was found that calcium and phosphate-containing ethanol-washed xerogels presented in vitro release of calcium (2–12 mg/L) and silicon ions (~60–75 mg/L) after one week of soaking in phosphate-buffered saline (PBS), as revealed by inductive coupled plasma (ICP) spectroscopy analysis. However, only the release of silicon was detected for water-washed samples. Besides, all the samples exhibited in vitro bioactivity in simulated body fluid (SBF), as well as enhanced in vitro cell growth and also significant focal adhesion development and maturation. Full article

Artificial membranes are models for biological systems and are important for applications. We introduce a dry two-step self-assembly method consisting of the high-vacuum evaporation of phospholipid molecules over silicon, followed by a subsequent annealing step in air. We evaporate dipalmitoylphosphatidylcholine (DPPC) molecules over bare silicon without the use of polymer cushions or solvents. High-resolution ellipsometry and AFM temperature-dependent measurements are performed in air to detect the characteristic phase transitions of DPPC bilayers. Complementary AFM force-spectroscopy breakthrough events are induced to detect single- and multi-bilayer formation. These combined experimental methods confirm the formation of stable non-hydrated supported lipid bilayers with phase transitions gel to ripple at 311.5 ± 0.9 K, ripple to liquid crystalline at 323.8 ± 2.5 K and liquid crystalline to fluid disordered at 330.4 ± 0.9 K, consistent with such structures reported in wet environments. We find that the AFM tip induces a restructuring or intercalation of the bilayer that is strongly related to the applied tip-force. These dry supported lipid bilayers show long-term stability. These findings are relevant for the development of functional biointerfaces, specifically for fabrication of biosensors and membrane protein platforms. The observed stability is relevant in the context of lifetimes of systems protected by bilayers in dry environments. Full article

The purpose of this work was to propose and evaluate a new composition for a bioactive glass-ceramic starting from the well-known 45S5 commercial product. Thus, we developed a modified version, including MgO, an oxide that turned out to induce superior mechanical properties and improved biological response. This had the following molar percentages: 46.1% SiO₂, 2.6% P₂O₅, 16.9% CaO, 10.0% MgO, and 24.4% Na₂O. The precursor alkoxides and nitrates were processed by a standard sol-gel technique, resulting in a glass-ceramic target, suitable for laser ablation experiments. Combeite (Na₂Ca₂Si₃O₉) was identified as a main crystalline phase within the calcined sol-gel powder, as well as in the case of the target sintered at 900 °C. The thin films were deposited on silicon substrates, at room temperature or 300 °C, being subsequently characterized from the material point of view, as well as in terms of bioactivity in simulated conditions and biocompatibility in relation to human fibroblast BJ cells. The investigations revealed the deposition of nanostructured glassy layers with a low proportion of crystalline domains; it was shown that a higher substrate temperature promoted the formation of surfaces with less irregularities, as a consequence of material arrangement into a shell with better morphological homogeneity. The complex elemental composition of the target was successfully transferred to the coatings, which ensured pronounced mineralization and a stimulating environment for the cell cultures. Thereby, both samples were covered with a thick layer of apatite after immersion in simulated body fluid for 28 days, and the one processed at room temperature was qualified to be the best in relation to the cells. Full article

Dentin hypersensitivity is one of the most common clinical conditions usually associated with exposed dentinal tubules. The purpose of this study was to identify the potential of a graphene oxide quantum dot coating for mesoporous bioactive glass nanoparticles as a new material for the treatment of dentin hypersensitivity by investigating its mineralization activity and dentinal tubules sealing. Mesoporous bioactive glass nanoparticle was fabricated by modified sol-gel synthesis. X-ray diffraction was performed to characterize the synthesized nanoparticle Fourier transform infra-red spectroscopy investigated the functionalized surfaces. The distribution of the specific surface area and the pore size was measure by Pore size analysis. The morphology of sample was observed by Field Emission Scanning Electron Microscope (FESEM) and Field Emission Transmission Electron Microscope (FETEM). After disk-shaped specimens of mesoporous bioactive glass nanoparticles and graphene oxide quantum dot coated mesoporous bioactive glass nanoparticles (n = 3) were soaked in the simulated body fluid for 0, 1, 5, 10,and 30 days, the amount of ions released was observed to confirm the ionic elution for mineralization. Sensitive tooth model discs (n = 20) were applied with two samples and evaluated the dentinal tubule sealing ability. The spherical mesoporous bioactive glass nanoparticles and graphene oxide quantum dot coated mesoporous bioactive glass nanoparticles with a diameter of about 500 nm were identified through FESEM and FETEM. The ion release capacity of both samples appeared to be very similar. The amount of ion released and in vitro mineralization tests confirmed that graphene oxide quantum dot coating of mesoporous bioactive glass nanoparticles did not inhibit the release of calcium, silicon and phosphate ions, but rather that graphene oxide quantum dot promoted hydroxyapatite formation. In the FESEM image of the sensitive tooth disc surface, it was observed that graphene oxide quantum dot coated mesoporous bioactive glass nanoparticles sealed tightly the dentinal tubules. The graphene oxide quantum dot coating of mesoporous bioactive glass nanoparticles not only showed the excellent dentinal sealing ability but also rapidly promoted mineralization while minimizing the size increase by coating the mesoporous bioactive glass nanoparticles. Full article