Silica Biocomposite Research Articles

Mesoporous silica/protein biocomposites: Surface, topography, thermal properties

The biocomposite systems based on mesoporous MCF silica support and protein molecules are characterized with regard to their surface, topographic, thermal properties. Mesoporous silica materials (MCF) covered by the adsorbed protein molecules (BSA and OVA) were examined and characterized by using various techniques including X-ray diffraction, the Fourier transform infrared spectroscopy with attenuated total reflectance, X-ray photoelectron spectroscopy and scanning electron microscopy with microanalysis. The results of study focused on a detailed analysis of microstructure (topography, texture), and chemistry (chemical bonds, functional groups, elemental composition) of protein/mesoporous silica biocomposite. Moreover, the thermal properties of prepared biomaterials were investigated by means of TG/DSC-FTIR-MS-coupled technique. These powerful methods provided detailed information for understanding protein adsorption on MCF. Significant differentiation in surface chemistry and topography of MCF material was observed after protein adsorption. Basing on the results of thermal analysis stronger changes of the surface properties and more stable interactions of biomolecules with MCF-d16 support were observed for larger BSA molecules compared to smaller ovalbumin ones.

Comparative Characterization of Chitosan/Gelatin/Geothermal Silica Biocomposites in Two-Dimensional Film and Three-Dimensional Scaffold Forms

Scaffold, a template resemble an extracellular matrix, contributes a necessary part in tissue engineering to accommodate the growth of cells. In the development of scaffold made from organic materials such as chitosan and gelatin, researchers have done various ways to modify its properties and one of them is by incorporate it with inorganic materials. This research explored the potential of silica derived from geothermal power plant waste as a biocomposite material for scaffold. Biocomposites with two-dimensional (2-D) film form were prepared by simple drying process at room temperature and ambient pressure, while three-dimensional (3-D) scaffold form were fabricated by freeze-drying. The obtained biocomposites were characterized by Fourier Transform Infra-Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). In addition, swelling and degradation tests were also performed on the films and scaffolds. The results showed that there are interactions between each component in chitosan/gelatin/geothermal silica biocomposites and the addition of geothermal silica decreases the swelling and degradation rates of the biocomposites. These results indicate that geothermal silica has a high potential to be used as an additive for controlling the physical properties of chitosan/gelatin scaffolds.

New Insights into the Effects of Surface Functionalization on the Peroxidase Activity of Cytochrome c Adsorbed on Silica Nanoparticles.

The immobilization of proteins on inorganic supports is attracting increasing interest since the realization of active surfaces finds application in enzyme-assisted catalysis, environmental sciences, and medical fields. In the present study, cytochrome c (cyt c) is adsorbed on silica nanoparticles (SNPs) and amino-functionalized silica nanoparticles (SNPs-APTES), which are prepared for this purpose and having a diameter of about 50 nm. The peroxidase activity of the protein is investigated under different experimental conditions, to evaluate the impact of differently charged surfaces on the catalytic activity of the biomolecule. The peroxidase activity of cyt c increases upon adsorption on SNPs, and it shows a linear behavior with nanoparticles concentration; on the other hand, the contact with increasing amounts of SNPs-APTES does not affect the catalytic activity of the protein. The kinetic profile of the oxidation reaction is altered for cyt c-SNPs sample, suggesting that upon adsorption, changes in the catalytic process take place. Moreover, we observe that the enhancement of peroxidase activity of cyt c-SNPs is almost completely inhibited in high-ionic-strength buffer: this indicates that the protein establishes electrostatic interactions with SNP. The spectroscopic properties of the adsorbed protein on the two different matrices are investigated by using fluorescence and Raman spectroscopies to account for the enzymatic activity of the hybrid materials. The fluorescence spectra of cyt c-silica bio-composites reveal that the adsorption on silica modifies the microenvironments of the emitting amino acid residues of the protein. Indeed, their fluorescence gains intensity and appears blue-shifted compared to that of the native protein; these modifications are more evident when cyt c is adsorbed on SNPs. Raman spectra suggest that both oxidation and spin state of heme iron change when cyt c is adsorbed on SNPs but not on SNPs-APTES. The spectroscopic data of biocomposite materials are discussed in terms of structural changes to account for the increment of peroxidase activity upon adsorption on the negatively charged surface of SNPs.

Rice husk‐derived porous carbon/silica particles as green filler for electronic package application

ABSTRACTBio‐based porous carbon/silica particles (denoted as RH‐carbon/silica) were successfully prepared from agricultural waste rice husk by using acid‐hydrothermal treatment and pyrolysis under nitrogen condition. As green filler, the cure behavior, thermal‐mechanical properties, and thermal conductivity of the epoxy‐carbon/silica biocomposites at different filler contents (5, 9, 17, 29 wt %) were characterized. Because of superior surface properties (surface area, porosity, and silica segment) and high content of carbon component in the RH‐carbon/silica, the characteristics of the biocomposites were significantly improved with the increase of the filler content. At 29 wt % of filler content, the epoxy biocomposites exhibit lower curing temperature (148 °C), lower CTE (42 ppm/°C), higher Tg (123 °C), higher storage modulus (4059 MPa), and higher effective thermal conductivity (0.29 W/mK). In brief, the RH‐carbon/silica particles that can serve not only as reinforcing agent but also as thermal transport medium used in epoxy composite, is a green and high‐performance filler for this purpose. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44699.

A novel application of nanohydroxyapatite/mesoporous silica biocomposite on treating dentin hypersensitivity: An in vitro study

ObjectivesTo fabricate a nanohydroxyapatite/mesoporous silica nanoparticle (nHAp@MSN) biocomposite and investigate its effectiveness on dentinal tubule occlusion, acid-resistant stability, and microtensile bond strength (MTBS). MethodsThe nHAp@MSN biocomposite was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption–desorption isotherms, field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). Thirty-two simulated sensitive dentin discs were prepared and randomly divided into four groups according to the following treatments (n=8 each): Group 1, no treatment; Group 2, NovaMin, 15 s×2; Group 3, MSN, 15 s×2; Group 4, nHAp@MSN, 15 s×2. Then, four discs per group were post-treated with 6wt.% citric acid challenge to test their acid-resistant stability. The effects on dentinal tubule occlusion were observed by FESEM. A self-etch adhesive (G-Bond) was applied to evaluate the MTBS. The cytotoxicity was detected using the Cell Counting Kit-8 (CCK-8) assay. ResultsResults revealed that the nHAp@MSN biocomposite was successfully fabricated. nHAp@MSN could effectively occlude the dentinal tubules, and the intratubular crystals were tightly associated with the tubular wall. After citric acid attack, nHAp@MSN exhibited the highest acid-resistant stability among the four groups. Moreover, no significant difference in MTBS was noted among the four groups (P>0.05). CCK-8 assay identified that nHAp@MSN induced no more than 20% cell death even at the highest concentration of 640μg/mL. ConclusionsThe application of the nHAp@MSN biocomposite resulted in efficient dentinal tubule occlusion, acid-resistant stability, and did not compromise immediate bond strength between dentin and self-etch adhesive system. Clinical significanceThe nHAp@MSN biocomposite indicates enormous potential as a new strategy for relieving dentin hypersensitivity.

3D Printing Bioceramic Porous Scaffolds with Good Mechanical Property and Cell Affinity.

Artificial bone grafting is widely used in current orthopedic surgery for bone defect problems. Unfortunately, surgeons remain unsatisfied with the current commercially available products. One of the major complaints is that these products cannot provide sufficient mechanical strength to support the human skeletal structure. In this study, we aimed to develop a bone scaffold with better mechanical property and good cell affinity by 3D printing (3DP) techniques. A self-developed 3D printer with laser-aided gelling (LAG) process was used to fabricate bioceramic scaffolds with inter-porous structures. To improve the mechanical property of the bioceramic parts after heating, CaCO3 was added to the silica ceramic slurry. CaCO3 was blended into a homogenous SiO2-sol dispersion at weight ratios varying from 0/100 to 5/95 to 9/91 (w/w). Bi-component CaCO3/SiO2-sol was prepared as a biocomposite for the 3DP scaffold. The well-mixed biocomposite was used to fabricate the bioceramic green part using the LAG method. The varied scaffolds were sintered at different temperatures ranging from 900 to 1500°C, and the mechanical property was subsequently analyzed. The scaffolds showed good property with the composite ratio of 5:95 CaCO3:SiO2 at a sintering temperature of 1300°C. The compressive strength was 47 MPa, and the porosity was 34%. The topography of the sintered 3DP bioceramic scaffold was examined by SEM, EDS and XRD. The silica bioceramic presented no cytotoxicity and good MG-63 osteoblast-like cell affinity, demonstrating good biocompatibility. Therefore, the new silica biocomposite is viable for fabricating 3DP bone bioceramics with improved mechanical property and good cell affinity.

Amperometric Biosensor for Choline Based on Gold Screen‐Printed Electrode Modified with Electrochemically‐Deposited Silica Biocomposite

AbstractA mediator‐free choline biosensor was developed using the electrochemically assisted sol‐gel deposition on gold screen‐printed electrodes. The addition of 12 mM of cationic surfactant CTAB in silica sol allowed enhancing the stability of the sensor. The modified electrode demonstrated catalytic activity and stable amperometric response to choline for over 3 weeks of exploitation with the sensitivity of 6 µA mM−1 and LOD of 6 µM. The interference of ascorbic acid was reduced by pretreating the analyzed solution with MnO2 powder. The application of the sensor with the purpose of identifying choline in the baby milk demonstrated satisfactory metrological characteristics.

Rice husk as bio-source of silica: preparation and characterization of PLA–silica bio-composites

Silica has been extracted from rice husk, employing a simple extraction for preparing poly(lactic acid) bio-composites with different filler contents.

Fabrication, characterization and in vitro profile based interaction with eukaryotic and prokaryotic cells of alginate–chitosan–silica biocomposite

This work is focused on the fabrication of a new drug delivery system based on polyanionic matrix (e.g. sodium alginate), polycationic matrix (e.g. chitosan) and silica network. The FT-IR, SEM, DTA-TG, eukaryotic cell cycle and viability, and in vitro assay of the influence of the biocomposite on the efficacy of antibiotic drugs were investigated. The obtained results demonstrated the biocompatibility and the ability of the fabricated biocomposite to maintain or improve the efficacy of the following antibiotics: piperacillin-tazobactam, cefepime, piperacillin, imipenem, gentamicin, ceftazidime against Pseudomonas aeruginosa ATCC 27853 and cefazolin, cefaclor, cefuroxime, ceftriaxone, cefoxitin, trimethoprim/sulfamethoxazole against Escherichia coli ATCC 25922 reference strains.

Cellular complexity captured in durable silica biocomposites

Tissue-derived cultured cells exhibit a remarkable range of morphological features in vitro, depending on phenotypic expression and environmental interactions. Translation of these cellular architectures into inorganic materials would provide routes to generate hierarchical nanomaterials with stabilized structures and functions. Here, we describe the fabrication of cell/silica composites (CSCs) and their conversion to silica replicas using mammalian cells as scaffolds to direct complex structure formation. Under mildly acidic solution conditions, silica deposition is restricted to the molecularly crowded cellular template. Inter- and intracellular heterogeneity from the nano- to macroscale is captured and dimensionally preserved in CSCs following drying and subjection to extreme temperatures allowing, for instance, size and shape preserving pyrolysis of cellular architectures to form conductive carbon replicas. The structural and behavioral malleability of the starting material (cultured cells) provides opportunities to develop robust and economical biocomposites with programmed structures and functions.

Liposomes as Protective Capsules for Active Silica Sol−Gel Biocomposite Synthesis

Using liposome to shield an enzyme from hostile chemical environments during the sol-gel formation process has resulted in a novel approach to synthesizing silica sol-gel biocomposite materials. By reporting the encapsulation of horseradish peroxidase and firefly luciferase, we demonstrate that this new protocol can produce silica biocomposites that are more active than trapping the enzymes directly into hydrogels.