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) (DTNB), 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 (DFT) 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 H2O2on silver shells, a quantitative SERS detection method for H2O2using 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-1was selected as the quantitative analysis signal. Within a concentration range of 0.12μM to 29.4μM, a good dose-response relationship was observed between H2O2concentration and Raman signal intensity. Fitting with a four-parameter logistic model yielded a calibration curveR2of 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 recoveriesmet 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 H2O2in complex matrix samples in the food, environmental, and biological sectors.