Surface-Enhanced Raman Scattering Active Core-Shell Ag NPs@Carbon Dots with Enzyme-Mimicking Activities for Label-Free Measurement Cholesterol

Serological-sensitive testing of cholesterol holds significant value in the fields of healthcare and clinical diagnosis. This study reports on the preparation of peroxidase-mimicking nanozymes through the wrapping of N, S-doped carbon dots (DCDs) on the surface of silver nanoparticles (Ag NPs@DCD). The shell–core structure of Ag NPs@DCD displays peroxidase-mimicking capability, with the potential to catalyze inactive Raman probe molecules into the Raman reporters. Furthermore, a “shell-isolated nanoparticles-enhanced Raman spectroscopy” structure exhibited an enhanced Raman signal of reporter molecules. Ag NPs@DCD were utilized to create a label-free SERS sensing system for high-performance detection of cholesterol in serum samples. These results demonstrate the potential of the novel nanozyme-based SERS approach for clinical diagnosis.