Biocatalytic Activity of Fungal Protease on Silver Nanoparticle-Loaded Zeolite X Microspheres

Silver nanoparticles are excellent biocompatible surfaces for the immobilization of enzymes. However, separation of the silver nanoparticle–enzyme bioconjugate material from the reaction medium is often difficult. In this study, we investigate the assembly of the silver nanoparticles on the surface of the amine-functionalized zeolite microspheres or formation of zeolite–silver nanoparticle "core–shell" structure and thereafter, using obtained structure in immobilization of fungal protease. The assembly of silver nanoparticles on zeolite surface occurs through the amine groups present in 3-aminopropyltrimethoxysilane (3-APTS). The fungal proteases bound to the massive "core–shell" structures can be easily separated from the reaction medium by mild centrifugation and exhibited excellent reuse characteristics. The biocatalytic activity of fungal protease in the bioconjugate was marginally enhanced relative to the free enzyme in solution.