Functionalized Stober silica as a support in immobilization process of lipase from Candida Rugosa

Lipase from Candida rugosa was immobilized onto modified Stober silica. Modification was made with 3-(2,3-epoxypropoxy)propyltrimethoxysilane and glutaraldehyde. The immobilization process by covalent binding was performed for 1 and 24 h using different concentrations of enzyme solution. The obtained immobilized biocatalysts were subjected to physicochemical characteristics. The characteristics of functional groups (FTIR, 13C CP MAS NMR), thermal stability (TG) and parameters of the porous structure (low temperature N2 sorption) were determined. An elemental analysis was performed to determine the content of nitrogen, carbon and hydrogen. Using a Bradford method the immobilization yield (IY) and amount (P) of lipase loaded onto support were calculated. The obtained systems were also tested to evaluate their catalytic activity in hydrolysis reaction of p-nitrophenyl palmitate (p-NPP) to p-nitrophenol (p-NP). The results confirmed the effectiveness of immobilization process and high hydrolytic activity (2270 U/g) of immobilized biocatalysts

Synthesis of hydroxyapatite in the presence of anionic surfactant

Hydroxyapatite was synthesized by precipitation method using an anionic surfactant (SDS) template, at ambient temperature and normal pressure. Phosphoric acid and disodium phosphate were used as a precursor of phosphorous, whereas calcium hydroxide and chloride were used as a precursor of calcium. The obtained hydroxyapatite was subjected to a wide range of physicochemical analysis using various measurement techniques. In order to get information about the properties of the obtained products, the following analysis of characteristics was performed: dispersion (NIBS), morphological (SEM), adsorptive (BET) and structural (XRD). Energy-dispersive X-ray spectroscopy and elemental analysis were also applied