Visible detection of biotin by thin-film interference: thickness control through exchange reaction of biotin/dethiobiotin–avidin bonding

Abstract

This work presents a unique method for the visible detection of site-specific molecular interactions between proteins and small molecules. In this method, a silica thin-film, which shows thin-film interference, was used as a substrate. On its surface, protein multilayers made up of avidin- and dethiobiotin-labeled bovine serum albumin (BSA) were constructed via the avidin–dethiobiotin bond. Film construction behaviors were confirmed visibly owing to the uniform change of the interference color. This multilayer was able to disassemble by biotin addition, taking advantage of the higher association constant of avidin–biotin bonding. Disassembling of the multilayer was also confirmable as a drastic color change seen by the naked eye.