Detection And Application Of Glutathione Based On SERS Spectroscopy Of Silver-based Self-assembled Nanofilms

The homeostasis and imbalance of glutathione（GSH）,an important antioxidant in organisms,is one of the key signals that reflect the health of organisms.Surface-enhanced Raman scattering（SERS）spectroscopy has been widely used in agricultural detection,chemical analysis,biomedicine and other fields due to its unique fingerprint expression,non-destructive and efficient detection and other advantages.In this paper,silver nanofilms and Ti₃C₂T_x/Ag NPs films were prepared based on the self-assembly method,and the sensitive detection of GSH and the application of GSH in drug release were studied by SERS spectroscopy.The main research contents are as follows:Silver nanospheres（Ag NPs）were synthesized by the reduction method and self-assembled into silver nanofilms on silicon wafers by means of an oil-water-oil three-phase system.The addition of GSH occurred the exchange reaction between sulfhydryl group and disulfide bond with probe molecule 3-（2-pyridine disulfide）propionate N-succimide（SPDP）containing pyridine ring and disulfide bond,which promoted the rupture of disulfide bond,thus enhancing the SERS signal of SPDP,and indirectly realizing the sensitive detection of glutathione with a detection limit of 10 n M and a good linear relationship in the range of 10-500 n M.The method had good stability when used to detect actual serum samples.Compared with the test results of commercial kits,the self-assembled silver film had the advantages of good uniformity,reproducibility and selective detection.To improve the performance of self-assembled silver nanofilms,two-dimensional transition metal carbon/nitrogen compound MXene-Ti₃C₂T_x were prepared by wet-chemical method,and Ti₃C₂T_x/Ag NPs films were self-assembled on positively charged silicon wafers by virtue of the high evaporation of ethyl acetate and Marangoni effect.The enhancement effect of the self-assembled composite film was improved by adjusting the concentration of Ti₃C₂T_x when the concentration of Ag NPs remained unchanged.Due to the unique advantages of Ti₃C₂T_x,the SERS detection limit of the composite film obtained by using 4-Mercaptobenzoic acid（4-MBA）as probe molecule was 10^-8 M,which showed a good linear relationship in the range of 10^-8-10^-3 M.Moreover,the method had good uniformity,repeatability and stability.The sensitive detection of serum showed that the film provides potential possibility and good application prospects for the detection of actual samples.The self-assembled Ti₃C₂T_x/Ag NPs film was used as a nanocarrier,and the loading and release of drugs on its surface were tracked by SERS.The anticancer drug doxorubicin（DOX）was successfully loaded onto the film via 4-MBA.The addition of GSH triggered the thiol exchange reaction on the surface of the Ti₃C₂T_x/Ag NPs film,leading to the shedding of 4-MBA from the surface,and the intensity of 4-MBA decreased with the increase of GSH concentration,which indirectly reflected the continuous reduction of DOX on the film..By characterizing the effect of different concentrations of GSH on the intensity of 4-MBA within a certain time range,it was shown that the reduction rate of DOX was faster within 3 h,and the reduction rate of DOX tended to be gentle after 6 h,which was better than the drug release effect triggered by Cys.Through the SERS characterization of serum,the loading of DOX and the GSH-triggered drug release effect were not greatly affected,maintaining a certain stability,laying a foundation for subsequent practical applications.