Development of Ultra-Fast Nanostructured Glucose Biosensor - Stoichiometry and Activity

Abstract

Neuronal activities are very fast and occur in the time scale of milliseconds. The current sensors for monitoring non-electroactive molecules in neuronal activities respond in the time scale of subsecond or several seconds. In order to capture the rapid transients of metabolites and non-electroactive molecules involved in neuronal activities in the brain, our lab recently showed a new enzyme based electrochemical sensor that can detect neurotransmitter acetylcholine in milliseconds. Subsequently, the glucose sensor is currently under development.Glucose is well known as the ubiquitous energy source. Extensive evidence indicates that glucose has significant effects on learning, memory processes and cognitive functions in humans. In our lab, micro-sized carbon fiber electrodes are firstly modified by gold nanoparticles (AuNP) to increase the surface area and surface curvature, and then glucose oxidase (GOx) is attached on the AuNP surface as the second layer which can induce the reaction of glucose with oxygen, subsequently the electronic signal produced from reaction will be captured by the electrochemical instrument. In order to optimize the sensor's working efficiency, the amount of GOx fully covering AuNP surface in bulk solution was quantified by flocculation assay using UV-Vis spectrophotometer and by direct and indirect quantification of stoichiometry using fluorescent spectrophotometer. The difference of enzyme activity between free GOx and immobilized GOx on AuNP was also studied. Later soon, the sensitivity, selectivity and stability of glucose sensor will be further investigated.