Facile Electrostatic Immobilization of Glucose Oxidase onto Citrate Capped Gold Nanoparticles for Surface-enhanced (Bio)-Catalysis

Abstract

Diabetes mellitus is a serious life-time health issue which has been increasing among the greater population, approximately 285 million people carrying this disease worldwide. In this study, we have functionalised the gold nanoparticles (AuNPs) with biocatalytic enabled optical property, it is the subject of the study for detecting glucose towards the development of photometric nano-transducer. The citrate capped AuNPs were used to warrant the electrostatic self-assembly of glucose oxidase (GOx) in the colloidal state. Glucose biocatalysis was studied through the nano-optical function of glucose on the surface of AuNPs. Using surface plasmonic resonance as analytical technique, we have determined the molecular binding interaction between glucose molecule and AuNPs surface. Based on the visible spectrum, successful immobilization of GOx onto AuNPs was demonstrated. The GOx functionalized AuNP exhibits catalytic activities for the oxidation of glucose and resulting change in the absorption peak of colloidal bio-assembly. It was observed that the absorbance at 520 nm was proportional to the concentration of glucose in the test samples. The Lambert-Beer law expresses the linear relationship between the absorbance and glucose concentration at a fixed wavelength, i.e., λmax at 520 nm. The precise detection of glucose is essential to monitor the biological level of glucose in the body. It can be concluded that the nano-(bio) gold surface exhibits a rapid photometric response with changes of glucose concentration in the test samples.