Determination of protein by hydroxypropyl-beta-cyclodextrin sensitized fluorescence quenching method with erythrosine sodium as a fluorescence probe.

The fluorescence spectral behavior of interaction of erythrosine sodium (ES) and bovine serum albumin (BSA) was investigated in hydroxypropyl-beta-cyclodextrin (HP-beta-CD) medium at pH 5.8. The excitation and emission wavelengths were 527 nm and 549 nm, respectively. The fluorescence intensity of ES increased due to the formed inclusion complex of HP-beta-CD and ES. But the fluorescence intensity of ES-HP-beta-CD diminished when BSA was added, and there was a linear relationship between the fluorescence quenching value of the system (deltaF = F(ES-HP-beta-CD) - F(BSA-ES-HP-beta-CD)) and the concentration of BSA. Based on this, a novel fluorescence quenching method for the determination of protein with ES as a fluorescence probe has been developed. Under the optimal conditions, the linear range of calibration curve for the determination of BSA was 0.5-32.0 microg mL(-1), and the detection limit was 49.2 ng mL(-1). It has been applied to the determination of serum in serum samples with satisfactory results.