Oriented Enzyme Immobilization at the Oil/Water Interface Enhances Catalytic Activity and Recyclability in a Pickering Emulsion

Enzyme-loaded water-in-oil Pickering emulsion is a promising system for biphasic catalytic reactions. In this paper, we report on oriented enzyme immobilization at the oil/water interface in a Pickering emulsion, in which CHO-Janus silica nanoparticles (CHO-JNPs) are utilized as a stabilizer of the emulsion and support for the enzyme to enhance both catalytic activity and recyclability. The catalytic performance of this immobilized enzyme (lipase from Candida sp.) was evaluated by esterification of hexanoic acid and 1-hexanol in a water/heptane biphasic medium. The results show that the specific catalytic activity of the immobilized enzyme (33.2 U mL(-1)) was 6.5 and 1.4 times higher than that of free enzyme (5.1 U mL(-1)) and encapsulated enzyme in the liquid core (23.3 U mL(-1)), respectively. Moreover, the immobilized enzyme demonstrated good stability and recyclability, retaining 75% of its activity after 9 cycles. We expect that oriented enzyme immobilization at the oil/water interface will be an important strategy for enhancing catalytic performance in Pickering emulsions.