Development of a heat-induced surface-enhanced Raman scattering sensing method for rapid detection of glutathione in aqueous solutions.

In this paper, a direct and simple detection method based on surface-enhanced Raman scattering (SERS) named "heat-induced SERS sensing method" is proposed for rapid determination of glutathione in aqueous solutions. It was found that highly enhanced SERS spectra of glutathione can be obtained if the silver colloids adsorbed with the analyte were heated up before the SERS measurement. Besides, it was revealed that silver particles with a size of approximately 60 nm are suitable for this study and that the SERS intensity is also influenced by the dropped sample volume, drying temperature, buffer concentration, and pH of the solution. It is noted that the thiol group of glutathione has a particularly strong interaction with a silver surface compared with other small biological molecules without a thiol group, validating this method to detect glutathione selectively. Under the optimal conditions, the detection of glutathione can be finished within 5 min, and the detection limit of ca. 50 nM can be reached, which is much better than the reported detection limit of glutathione (approximately 1 microM) by SERS. The enhancement factor of the proposed heat-induced SERS sensing method for the detection of glutathione is about 7.5 x 10(6). The proposed method holds a specific selectivity toward glutathione, facilitating its rapid detection in practical applications.