Application of functionalized Ag nanoparticles for the determination of proteins at nanogram levels using the resonance light scattering method

A novel method for the determination of proteins in aqueous solutions has been developed based on the enhancement of resonance light scattering (RLS) of Ag nanoparticles in the presence of proteins. Factors including acidity of the media, concentration of Ag hydrosol, reaction time, temperature, and interference of non-protein substances were investigated. Under the optimal conditions, with the enhanced RLS signals at 452 nm, the linear ranges of calibration curves were 0-0.8 mug mL(-1) for bovine serum albumin (BSA), 0-1.2 mug mL(-1) for human serum albumin (HSA), and 0-2.5 mug mL(-1) for human gamma-IgG (gamma-IgG), respectively. The detection limits were 1.3 ng mL(-1) for BSA, 10 ng mL(-1) for HAS, and 5.7 ng mL(-1) for gamma-IgG. This method has been applied to the analysis of synthetic samples and real human serum samples, and the results were in good agreement with those reported by the hospital, indicating that the method presented here is not only sensitive and simple, but also reliable and suitable for practical applications.