Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins

Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With Δλ=190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 μg mL−1 for bovine serum albumin (BSA), 0.01–6.0 μg mL−1 for human serum albumin (HSA), 0.05–8.0 μg mL−1 for γ-globulin (γ-G), and 0.04–4.0 μg mL−1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 μg mL−1 BSA, 1.90% for 1.0 μg mL−1 HSA, 1.65% for 1.0 μg mL−1 γ-G, and 2.32% for 1.0 μg mL−1 ovalbumin.