Spectral Properties of K<sub>2</sub>PtCl<sub>6</sub>-KI-Protein Associated Particle Systems and its Application to Resonance Scattering Spectral Analysis

Abstract

In suitable pH value of Walpole buffer solution and in the presence of surfactant Triton X-10 and alcohol, PtCl62- reacts with I- to form PtI62-. By means of the electrostatic and hydrophobic forces, proteins with positive charge, such as human serum albumin (HSA), bovine serum albumin (BSA), human immunoglobulin (IgG) and ovalbumin (OVA), associates with PtI62- to form stable [protein-(PtI6)n]m association particles which cause substantial enhancement of Rayleigh scattering and interface fluorescence. They produce three Rayleigh scattering peaks at 330 nm, 420 nm and 464 nm and a resonance scattering peak at 580 nm, among which the strongest peak is at 464 nm. The four kinds of protein association particle system all exhibit a strong fluorescence peak at 466 nm, while the HSA fluorescence peak at 360 nm was quenched with the formation of the association particle. The cause of the Rayleigh scattering peaks of the association particle system was considered in detail, and the relationship between the Rayleigh scattering and fluorescence of the association particle (the means diameter is about 470 nm) and the fluorescence quenching of HSA was interpreted. Under the optimal experimental conditions, there is a good linear relationship between the scattering intensity (I464 nm) and protein concentration in the range of 0.05~25μg/mL HSA, 0.05~25μg/mL BSA, 0.3~30μg/mL IgG and 0.1~16μg/mL OVA respectively, with a detection limit of 20 ng/mL HSA, 26 ng/mL BSA, 40 ng/mL IgG and 70 ng/mL OVA. This assay has been applied to the determination of the albumin of human serum samples with satisfactory results.