Synthesis of Gold Nanoclusters Encapsulated by Human Serum Albumin and its Application as Glucose Detection Based on Fluorescence Technique

Abstract

Protein-stabilized gold nanoclusters have been intensively studied due to their excellent fluorescent properties and potential biomedical applications. Human Serum Albumin is abundant in human blood. Here, we synthesized human serum albumin-stabilized gold nanoclusters. The gold nanoclusters were characterized and used for glucose sensing. It is found that the human serum albumin encapsulated gold nanoclusters emit bright red fluorescent with a long fluorescence lifetime in the range of microseconds. The fluorescence intensity for gold nanoclusters decreased as the concentration of added glucose increased. The fluorescence intensity decreases due to the by-product (H2O2) from the enzymatic reaction of glucose oxidase. The Au-S bond can be destroyed by Hydrogen Peroxidase (H2O2). The fluorescence lifetime value of gold nanoclusters is unchanged in the presence and absence of glucose. This unchanged fluorescence lifetime obeyed a simple static quenching mechanism and indicated the destruction in the structure of gold nanoclusters, leading to the quenching of fluorescence intensity. This work suggests that human serum albumin-encapsulated gold nanoclusters can be used for glucose detection with a detection limit of 0.5×10-6 mol/L.