A Single Nanoprobe for Ratiometric Imaging and Biosensing of Hypochlorite and Glutathione in Live Cells Using Surface-Enhanced Raman Scattering

Hypochlorite (ClO^-) and glutathione (GSH) have been reported to closely correlate with oxidative stress and related diseases; however, a clear mechanism is still unknown, mainly owing to a lack of accurate analytical methods for live cells. Herein we create a novel surface-enhanced Raman scattering (SERS) nanoprobe, 4-mercaptophenol (4-MP)-functionalized gold flowers (AuF/MP), for imaging and biosensing of ClO^- and GSH in RAW 264.7 macrophage cells upon oxidative stress. The SERS spectra of AuF/MP change with the reaction between ClO^- and 4-MP on AuFs within 1 min and then recover after reaction with GSH, resulting in the ratiometric detection of ClO^- and GSH with high accuracy. The single SERS probe also shows high selectivity for ClO^- and GSH detection against other reactive oxygen species and amino acids which may exist in biological systems, as well as remarkable sensitivity ascribed to a larger amount of hot spots on AuFs. The significant analytical performance of the developed nanoprobe, together with good biocompatibility and high cell-permeability, enables the present SERS probe imaging and real-time detection of ClO^- and GSH in live cells upon oxidative stress.