Highly Efficient Enzyme Immobilization and Stabilization within Meso-Structured Onion-Like Silica for Biodiesel Production

Highly Efficient Enzyme Immobilization and Stabilization within Meso-Structured Onion-like Silica for Biodiesel Production

Seung-Hyun Jun, Jinwoo Lee, Taeghwan Hyeon, and Jungbae Kim*

Department of Chemical and Biological Engineering, Korea University, Seoul, Korea

Advanced Functional Nanomaterials Laboratory, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Korea

National Creative Research Initiative Center for Oxide Nanocrystalline Materials and School of Chemical Engineering, Seoul National University, Seoul 151-744, Korea

Abstract

Enzyme was immobilized and stabilized in meso-structured onion-like silica (Meso-Onion-S), which has highly-curved meso-pores of 10 nm diameter in a multi-shell structure in a form of nanoscale enzyme reactors (NERs). NERs were prepared via a two-step process of enzyme adsorption and subsequent enzyme crosslinking, which effectively prevents the leaching of crosslinked enzyme aggregates from highly-curved mesopores of Meso-Onion-S. As a result, NERs in Meso-Onion-S significantly improved the enzyme stability as well as the enzyme loading. For example, NER of lipase (NER-LP) was stable under rigorous shaking for 40 days, while the control sample of adsorbed LP (ADS-LP) with no enzyme crosslinking showed a rapid inactivation due to rigorous enzyme leaching under shaking. Stable NER-LP was successfully employed to produce biodiesels, fatty acid methyl esters, from the LP-catalyzed transesterification of soybean oil with methanol. Interestingly, the specific activity of NER-LP was 23 and 10 times higher than those of free LP and ADS-LP, respectively, revealing the importance of LP stabilization in the form of NER-LP in the presence of organic solvents.