Preparation of functionalized nanostructures on microchannel surface and their use for enzyme microreactors

Abstract

Microreactors have become a new and promising technology in chemistry, chemical engineering, and biotechnology fields. Nanostructures have attracted interest as a reaction apparatus especially for catalytic reaction. The present study develops a simple method for nanostructure preparation that is suitably functionalized for a pile-up enzyme microreaction system. First, we developed a simple method to prepare a nanostructure on a microchannel surface. We applied the sol–gel procedure, which has been utilized for porous structure preparation in batchwise systems. We immobilized the enzyme through amide-bond formation with the surface. The cucumisin-immobilized microreactor showed high efficiency that enable hydrolysis of substrate within 2 s. This result demonstrates that the microreactor has sufficient performance to be capable of small quantity industrial scale processing. Next, we tried to develop a reversible immobilization method for proteins on a microchannel surface. This should solve the enzyme lifetime problem because we are thereby able to detach a denatured enzyme and replace it with a fresh one. We examined two methods, immobilization through disulfide bond and Ni-complex using His-tag. These methods might be useful for further development of highly efficient pile-up enzyme microreaction systems.