A Systematic Study of the Use of DL-Tartaric Acid in the Synthesis of Silica Materials Obtained by the Sol-Gel Method

DL-tartaric acid was used as a template for the formation of silica nanotubes and spheres by the sol-gel method from tetraethylorthosilicate (TEOS) as silica source. The reactions were carried out in ethanol/water mixtures in the presence of aqueous ammonia, between 0°C and 75°C, using both stirred and non-stirred conditions. TEM and SEM images show that the yield and microstructure of the silica is influenced by the synthetic conditions (temperature, ammonia (aq) concentration, gelation time, solvent mixture). It was observed that the chiral form of the tartaric acid used and the diffusion of TEOS to the template determines the eventual silica structure.     

Silica Nanowires Templated by Amyloid‐like Fibrils

Many peptides self‐assemble to form amyloid fibrils. We previously explored the sequence propensity to form amyloid using variants of a designed peptide with sequence KFFEAAAKKFFE. These variant peptides form highly stable amyloid fibrils with varied lateral assembly and are ideal to template further assembly of non‐proteinaceous material. Herein, we show that the fibrils formed by peptide variants can be coated with a layer of silica to produce silica nanowires using tetraethyl‐orthosilicate. The resulting nanowires were characterized using electron microscopy (TEM), X‐ray fiber diffraction, FTIR and cross‐section EM to reveal a nanostructure with peptidic core. Lysine residues play a role in templating the formation of silica on the fibril surface and, using this library of peptides, we have explored the contributions of lysine as well as arginine to silica templating, and find that sequence plays an important role in determining the physical nature and structure of the resulting nanowires.     

Immobilization of lactate dehydrogenase on tetraethylorthosilicate-derived sol-gel films for application to lactate biosensor

Tetraethylorthosilicate (TEOS)-derived sol-gel films were utilized for the immobilization of lactate dehydrogenase (LDH) by physical adsorption and sol-gel/LDH/sol-gel sandwich configuration. An attempt was made to ascertain the optimum pH and temperature for the immobilized LDH. It was shown that TEOS-derived sol-gel films containing physically adsorbed LDH exhibited linearity from 0.5 to 4 mM, whereas those containing LDH in sandwich configuration showed linearity from 0.5 to 3 mM l-lactate. These sol-gel films, immobilized with LDH, were found to be stable for about 4 weeks at 4–10°C.     

Facile synthesis of small crystal ZSM-5 zeolite by acid-catalyzed hydrolysis of tetraethylorthosilicate

Small crystal zeolites ZSM-5 with sizes of 150–300 nm were synthesized using the colloidal silicate precursors as the silica source created by the acid-catalyzed hydrolysis of tetraethylorthosilicate with tetrapropylammonium bromide as the structure-directing agent within a short crystallization time of 20–35 h. The precursors and final products were detected by XRD, SEM, ICP and DLS. Supported by the National Natural Science Foundation of China (Grant No. 20776069), Key Natural Science Foundation for Universities of Jiangsu Province (Grant No. 06KJA53012), and Program for Changjiang Scholars and Innovative Research Team in University (Grant No. PCSIRT 0732)     

Effect of sol‐gel polymerization of tetraethylorthosilicate on internal aggregate structure in zinc‐neutralized ethylene‐methacrylic acid ionomers

Sol‐gel reactions of tetraethylorthosilicate have been performed in three different zinc‐neutralized ethylene‐methacrylic acid copolymer ionomers for the purpose of creating nanostructured organic‐inorganic materials with enhanced properties. Extended X‐ray absorption fine structure (EXAFS) spectroscopy was used to understand the effect of this in situ reaction on ionic aggregate morphology. EXAFS spectra showed that no large changes occurred in the aggregate structure, indicating that the internal environment of the aggregates did not nucleate the reaction, at least to the extent that the ionic domains were significantly undisrupted. However, small changes in EXAFS patterns were evident. These changes could be a result of nucleation of the reaction at the edges of the aggregates, or aggregate size rearrangement caused by the insertion of inorganic moieties into the polymer. However, the results indicate that the latter cannot include significant amounts of unaggregated zinc ions. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 197–200, 2001     

Influence of fluorination of xerogels on the intensity of photoluminescence of gamma-irradiated sol-gel quartz glasses

We investigated the influence of fluorination of xerogel on the intensity of luminescence with a maximum at 1.9 eV attributable to nonbridging oxygen atoms in gamma-quanta irradiated sol-gel quartzglasses. It is established that in samples with a high content of hydroxyl groups (more than 8 ppm) the intensity of this luminescence correlates with the content of hydroxyl in the initial samples. Fluorination of gels at the technological stage before sintering substantially reduces the number of silanol groups, improves the quality of glass, and increases their radiative-optical stability. Translated from Zhurnal Priklandoi Spektroskopii, Vol. 67, No. 2, pp. 266–268, March–April, 2000. This work was carried out with financial support from the Belarusian Republican Foundation for Fundamental Research, project F98-139.