[Application of L-cysteine-capped nano-ZnS as a fluorescence probe to the determination of proteins in human serum].

Nanometer-sized L-cysteine-capped ZnS particles as a fluorescence probe were synthesized, and the effect of proteins on the fluorescence intensity has been investigated. With deltalambda = 190 nm, the maximum and constant synchronous fluorescence enhancement was produced at 268.0 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins was developed. Under optimum conditions, the calibration curve was linear over the range 0.05-6.0 microg x mL(-1) for human serum albumin (HSA), and 0.05-8.0 microg x mL(-1) for gamma-globulin (gamma-G), respectively. The relative standard deviations of seven measurements were 1.90% for 1.0 microg x mL(-1) HSA, and 1.65% for 1.0 microg mL(-1) gamma-G.