Synthesis and Characteristics of Mesoporous Sol-gels for Lipase Immobilization

Enzyme cost is the major problem for industrial scale application. Immobilization is a promisingapproach to moderate the enzyme cost factor and increase its stability and activity. In this study, sol-gelmethod was used to prepare the immobilization platform and entrapped lipase as one of the most usedenzyme in dairy processing, cosmetics and pharmaceutical industries. Lipase from Candida rugosawas immobilized onto glycidoxypropyltrimethoxysilane (GPTMS) and tetramethoxysilane (TMOS)derived sol-gels and its characteristics and hyrdrolytic activity were investigated. Michaelis-Mentenkinetic properties reveal that although free enzyme can catalyze the reaction faster, but it has loweraffinity for substrate molecules compared to sol-gel immobilized lipase. Entrapped lipase retained 67% of its initial activity after six reaction cycles. It showed 100% activity compared to free lipasepowder at 40-45°C. In pH 9, as free enzyme lost 90 % of its initial activity, immobilized lipase lostonly 29% of its activity. Immobilized enzyme was more stable toward different pHs (100% activity atpH 7.5 compared to free form). Morphological characteristics of the immobilized enzyme wereinvestigated by SEM images and BET. The sample had specific surface area and mean pore diameterof 2.599 m2/g and 46.13 nm, respectively.

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Keywords:EnzymesSol-gel ProcessHydrolytic activityImmobilizationKineticsMesoporous