Core-shell SERS nanoprobes for ROS detection and imaging during apoptosis

Reactive oxygen species (ROS) are critical intermediates in intracellular redox reactions and play a key role in apoptosis. Here, a novel surface-enhanced Raman scattering (SERS) nanoprobe was developed for the real-time detection and imaging of intracellular ROS. The problems of easy quenching of fluorescence detection and difficult preparation of electrochemical detection electrode were improved. The probe adopted a simple core-shell structure to perform dynamic monitoring of ROS with excellent biological stability and simple preparation. The nanoprobe featured a sandwich structure. Due to Au-Ag core-shell structure the Raman signals of 4-mercaptobenzonitrile (4-MBN) were significantly enhanced. Excessive ROS, due to strong oxidative properties, can etch the silver shell, thereby reducing its thickness and weakening the coupling between the gold core and the silver shell. This etching process diminished Raman signals of 4-MBN. The nanoprobe demonstrated high sensitivity for the quantitative detection of ROS in vitro. The linear range was 100 nM–1000 nM, and the detection limit was 43.91 nM. Specifically, PAT was used to establish a model of oxidative damage in HepG2 cells, and the probe was successfully applied to real-time detection and imaging of ROS during HepG2 cell damage. The probe designed in this study proved to have good stability and reproducibility, high sensitivity for the detection of ROS in vitro. It had low toxicity and good biocompatibility, which was suitable for the detection and imaging of ROS in HepG2 cell. It also played an important role in the in-depth understanding of the pathogenesis and treatment mechanism of ROS-related diseases.