Development of Au@DTNB@Ag nanoprobes and a method for detecting hydrogen peroxide

While traditional hydrogen peroxide detection methods each have their own advantages in different application scenarios, some methods still suffer from issues such as insufficient sensitivity, limited specificity, complex procedures, or poor resistance to interference. In this study, we developed an Au@Ag core-shell surface-enhanced Raman spectroscopy (SERS) nanoprobe incorporating the Raman-reporting molecule 5,5'-Disulfanediylbis(2-nitrobenzoic acid), for the highly sensitive and specific quantitative detection of H₂O₂. Gold nanoparticles were prepared using the sodium citrate reduction method, and Au@DTNB@Ag nanoprobes were synthesized via the seed-growth method. The structures were systematically characterized using transmission electron microscopy, zeta potential measurements, and Raman spectroscopy. By combining finite element simulations with density functional theory calculations, we have elucidated the SERS enhancement mechanism underlying the synergistic interaction between electromagnetic and chemical enhancement in this nanoprobe; based on the concentration-dependent oxidative etching effect of H₂O₂ on silver shells, a quantitative SERS detection method for H₂O₂ using the nanoprobes was established, and systematic methodological validation was completed. The results indicate that the prepared Au@DTNB@Ag nanoprobes possess a uniform core-shell structure and excellent SERS activity. The characteristic Raman peak of DTNB at 1294 cm⁻¹ was selected as the quantitative analysis signal. Within a concentration range of 0.12 μM to 29.4 μM, a good dose-response relationship was observed between H₂O₂ concentration and Raman signal intensity. Fitting with a four-parameter logistic model yielded a calibration curve R² of 0.99915. The detection stability was excellent, coefficients of variation for measured concentrations at medium and high concentration levels were all below 10%, and the spike recoveries met the acceptable standards for trace analysis. The detection method developed in this study is simple to operate and provides rapid results. It demonstrates certain advantages in terms of sensitivity and resistance to interference, offering a new technical option for the quantitative detection of H₂O₂ in complex matrix samples in the food, environmental, and biological sectors.