Enzymatic Glucose Nanosensor Based on Fluorophore Co-Doped Silica Nanotube

Abstract

A novel incentive enzymatic glucose detection using ratiometric fluorescent co-doped silica nanotube was developed. With the great biocompatibility and multifunctional structure, silica nanotube allows both co-encapsulation of fluorescent dyes and bioconjugation of glucose oxidase without increasing its dynamic size. In our study, two kinds of fluorophore, namely Fluorescent isothiocyanate and Tetramethyl rhodamine, were employed as reporting and calibrating probe, respectively. Firstly, silica nanotubes were synthesized using anodic alumina membrane and Tetramethyl rhodamine, pH-insensitive dye, was embedded inside silica matrix during synthesis. Secondly, Fluorescent isothiocyanate, pH-sensitive dye, was subsequently embedded inside hollow void of nanotube using nano-molding lithography. Finally, glucose oxidase was covalently immobilized onto the outer surface of free-standing silica nanotubes. During enzymatic reaction, gluconic acid was generated and decreased pH of solution. The concentration of glucose was quantified by fluorescent ratiometric measurement based on the decreased emission intensity of Fluoresecein thioisocyanate compared to that of Tetramethyl rhodamine.