Hirohiko Tsuzuki

Bifunctional Langmuir-Blodgett film for enzyme immobilization and amperometric biosensor sensitization

Abstract A Langmuir-Blodgett (LB) film consisting of octadecylamine as the binding site for the enzyme molecule, an amphiphilic ferrocene derivative as the electron mediator, and octadecanol as the matrix for these molecules was deposited on a hydrophobized tin oxide (SnO 2 ) electrode. Glucose oxidase (GOx) was then covalently immobilized on the film via glutaraldehyde, and the GOx electrode thus obtained worked as an amperometric glucose sensor based on the oxidation of hydrogen peroxide liberated by the enzymatic reaction. The sensitivity of this sensor was about twice as high as that of a GOx electrode prepared with the same LB film as above but without the ferrocene. The sensitizing effect of ferrocene was attributed to its capability of electron mediation between hydrogen peroxide and the SnO 2 electrode.

Open-sandwich molecular imprinting: making a recognition matrix with antigen-imprinted antibody fragments.

A novel antibody-polymer conjugation method termed open-sandwich molecular imprinting (OS-MIP) has been proposed to produce a specific recognition matrix in the presence of a target antigen. The resultant carboxymethyldextran matrix conjugated with two separate antibody variable region fragments imprinted with the cognate antigen showed higher antigen-binding capacity than non-imprinted ones and was successfully used to sensitively monitor multiple antigen binding/desorption events by a surface plasmon resonance biosensor. Furthermore, when each fragment was labeled with different fluorophores before conjugation, the fluorescence signals of the matrix made by OS-MIP clearly showed an antigen concentration dependent increase in Förster resonance energy transfer between the two dyes. By using a combination of various methods for detecting interaction, OS-MIP will be a useful platform for detecting various targets from small molecules to proteins with high sensitivity and specificity.