Colorimetric/SERS dual-mode sensing of glucose based on cascade reaction of peroxidase-like Au@Pt/Fe-DACDs nanozyme

This study synthesized Fe-doped dopamine carbon dots (Fe-DACDs) as a reducing agent and template hybrid Au and Pt nanoparticles (Au@Pt/Fe-DACDs). Au@Pt/Fe-DACDs with core–shell structures show strong peroxidase (POD)-like activity at physiological pH. A colorimetric and surface-enhanced Raman scattering (SERS) dual-mode detection system for glucose in human serum was constructed by combining Au@Pt/Fe-DACDs with natural glucose oxidase (GOx). The cascade catalysis reactions convert glucose into hydrogen peroxide (H₂O₂), and then, the Au@Pt/Fe-DACDs as both POD-like nanozyme and Raman-enhancers oxidize colorless and weak Raman-active 3,3′,5,5′-tetramethylbenzidine (TMB) into blue and strong Raman-active ox-TMB. The linear response ranges of glucose are from 0.02 to 1 mM, with a detection limit of 2.3 μM for colorimetric detection and 0.01 mM to 0.7 mM with a detection limit of 1.4 μM for SERS sensors. Glucose content in human serum samples was successfully assayed with a good recovery from 97.6 to 105.3%. Overall, these results demonstrate a new way of designing biological detection systems based on SERS and colorimetric dual-mode sensing.