Fluorescence Immunosensing of Insulin via Protein Functionalized Gold Nanoclusters

A novel fluorescent immunosensor for the determination of insulin, an important peptide hormone, has been fabricated in homogeneous solution. Bovine serum albumin (BSA) capped gold nanoclusters (AuNCs), being highly biocompatible, were used to label the insulin antibody (Ab). In presence of the target antigen, insulin (Ag), specific immunoreaction between Ab and Ag takes place leading to the fluorescence recovery of AuNCs that provided signal readout for the immunosensing process. A linear relationship between the fluorescence signal and concentration of insulin was obtained in the range of 4.9 × 10^-9 g/mL to 3.8 × 10^-8 g/mL, with a detection limit of 1.1 × 10^-10 g/mL. Furthermore, application of the present approach in human insulin injection and synthetic blood serum has been demonstrated, thus promising an efficient platform for clinical diagnostics.