Gold-Nanoparticle-Encapsulated ZIF-8 for a Mediator-Free Enzymatic Glucose Sensor by Amperometry

A novel method has been developed for the encapsulation of gold nanoparticles (AuNPs) and glucose oxidase (GOx) together into the cavity of a zeolitic imidazolate framework (ZIF-8) in aqueous media and subsequently used for amperometric glucose sensing application. ZIF-8 is a highly efficient, stable (thermally and chemically) microstructure and possesses a large surface area with a unique cavity to accommodate both AuNPs and GOx. The as-synthesized composite is thoroughly characterized by various physicochemical methods and confirms the uniform distribution of AuNPs within the metal-organic framework cavity. The presence of highly conducting AuNPs enhances the activity of GOx and facilitates the mediator-free tandem electrocatalytic reactions of both glucose oxidation and oxygen reduction. Further, the nanocomposite exhibits admirable stability with low-level detection of glucose in aqueous media (SO nM glucose) by using a very low concentration of GOx (62 mu g in 1 mL).