Nanostructured fluorescent biosensor for glucose detection

Self-assembled thin films containing embedded enzymes and fluorescent indicators are being developed for use as highly specific glucose biosensors for neurochemical research. The sensors are fabricated using electrostatic layer-by-layer (LBL) adsorption to create oxygen-sensitive (ruthenium-based) layers, the fluorescent intensity of which responds to changes in local oxygen levels. Oxygen is consumed locally by the reaction between glucose oxidase (GOx) molecules and glucose. Quartz slides serve as the templates for our sensors and fabrication is carried out through the alternate adsorption of multiple levels of {GOx/polycation} and {polycation-ruthenium/polyanion}. Additional fluorescence bilayers were included as an internal intensity reference to allow ratiometric monitoring. Films adsorbed to the quartz slide templates are being studied to understand the fundamental chemical and optical properties, including enzymatic activity, spectral shape and emission intensity. Fluorescence is also maintained, though blue shifts are observed in emission spectra, and indicator activity remains. Macro-template characterization studies demonstrate the feasibility of LBL assembly architecture for fabrication of glucose biosensors, and future work will focus on assembly on nanoparticle templates with optimized response for neural monitoring.