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A method was developed for atom transfer radical polymerization (ATRP) synthesis of a nanocomposite consisting of dispersed, nanosized hard particles in a thermoplastic matrix. Octafunctional cubic silsesquioxanes were used as a platform to synthesize 8-arm star poly(methyl methacrylate) (PMMA) via ATRP. The cubic silsesquioxane, octakis(hydridodimethylsiloxy)octasilsesquioxane (Q 8M8 H ), was converted to either octakis(2-bromo-2-methylpropionoxypropyldimethylsiloxy)octasilsesquioxane (OBPS) or the octaethylbenzyl chloride analogue. The bromo ester was successfully employed as an ATRP initiator using CuCl as catalyst, leading to formation of PMMA arms with controlled molecular weights and hence to nanocomposites with essentially complete control of dispersion and solids loading. The catalyst and initiator concentrations were demonstrated to affect the molecular weight distribution and the occurrence of star-star coupling caused by inevitable termination reactions.

Polyvinyl alcohol (PVA), PVA crosslinked with glutaraldehyde hydrogels (PVA/GA), PVA with tetraethylorthosilicate (PVA/TEOS) and PVA/GA/TEOS hybrids with recombinant MPB70 protein (rMPB70) incorporated were chemically characterized by Fourier transform infrared spectroscopy (FTIR). FTIR spectra of PVA hydrogel samples showed the absorption regions of the specific chemical groups associated with poly(vinyl alcohol) (-OH, -CO, -CH2) and PVA/GA confirming the formation of crosslinked hydrogel (duplet -CH). It was observed C-H broad alkyl stretching band (n = 2850-3000 cm-1) and typical strong hydroxyl bands for free alcohol (nonbonded -OH stretching band at n = 3600-3650 cm-1), and hydrogen bonded band (n = 3200-3570 cm-1). The most important vibration bands related to silane alcoxides have been verified on FTIR spectra of PVA/TEOS and PVA/GA/TEOS hybrids (Si-O-Si, n = 1080 and n = 450 cm-1; Si-OH, n = 950 cm-1). FTIR spectra of f PVA hydrogel with rMPB70 incorporated have indicated the specific groups usually found in protein structures, such as amides I, II and III, at 1680-1620 cm-1, 1580-1480 cm-1 and 1246 cm-1, respectively. These results have given strong evidence that recombinant protein rMPB70 was successfully adsorbed in the hydrogels and hybrids networks. These PVA based hydrogels and hybrids were further used in immunological assays (Enzyme-Linked Immunosorbent Assay - ELISA). Tests were performed to detect antibodies against rMPB70 protein in serum samples from bovines that were positive in the tuberculin test. Corresponding tests were carried out without PVA samples in microtiter plates as control. Similar results were found for commercially available microplates and PVA based hydrogels and hybrids developed in the present work regarding to immunoassay sensitivity and specificity response

Several techniques have been utilized for the preparation of hydroxyapatite (HA) and other calcium phosphates for the development of biomaterials. It is vital to know the reaction kinetics to be able to control the material obtained by the aqueous solution route. In the present work, HA has been produced by different wet precipitation processes and different experimental conditions. Calcium hydroxide, calcium phosphate, ammonium phosphate and phosphoric acid were used as reagents. The precipitate was dried at 100 °C overnight and then some samples were treated at 900 °C for 2 h. The powder samples were characterized by scanning electron microscopy (SEM), X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses. SEM photomicrographs showed an aggregate powder, granular to dense and suggested typical columnar particles. Qualitative XRF showed that the main components of HA powders were calcium and phosphorus. Pure HA and other phases according to processing parameters were observed by XRD analysis.

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In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS) was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR), shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures

In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR). Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH) stretching vibration at around 950 cm-1 and the Si-O-(Si) vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH) stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H) bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel

The purpose of this study was to develop novel hybrid organic-inorganic materials based on poly(vinyl alcohol) (PVA) polymer chemically crosslinked network to be tested as solid support on bovine herpesvirus immunoassay. Hybrids were synthesized by reacting PVA with three different alkoxysilanes modifying chemical groups: tetraethoxysilane (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). PVA-derived hybrids were also modified by chemically crosslinking with glutaraldehyde (GA) during the synthesis reaction. In order to investigate the structure in the nanometer-scale, PVA-derived hybrids were characterized by using small-angle x-ray scattering synchrotron radiation (SAXS) and x-ray diffraction (XRD). PVA hybrids' chemical functionalities and their interaction with herpesviruses were also characterized by Fourier transform infrared spectroscopy (FTIR). The bioactivity assays were tested through enzyme linked immunosorbent assay (ELISA). SAXS results have indicated nano-ordered disperse domains for PVA hybrids with different x-ray scattering patterns for PVA polymer and PVA-derived hybrids. FTIR spectra have shown major vibration bands associated with organic-inorganic chemical groups present in the PVA, PVA-derived by silane modifier and PVA chemically crosslinked by GA. The immunoassay results have shown that PVA hybrids with chemically functionalized structures regulated to some extent the specific bioimmobilization of herpesvirus onto solid phase. We think that it is due to the overall balance of forces associated with van der Waals interaction, hydrophilic and hydrophobic forces and steric hindrance acting at the surface. PVA and PVA-derived hybrid materials were successfully produced with GA crosslinking in a nanometer-scale network. Also, such a PVA-based material could be advantageously used in immunoassays with enhanced specificity for diagnosis.