Characterization of Au@PtNP/GO nanozyme and its application to electrochemical microfluidic devices for quantification of hydrogen peroxide

Nanostructured artificial enzymes, known as nanozymes, have been considered effective alternatives for natural enzymes with the attractive advantages. Herein, bimetallic Au and Pt nanoparticles with graphene oxide (GO) were immobilized chemically on the surface of agarose microbeads. Due to the synergistic effect of the bimetallic nanoparticles and GO (Au@PtNP/GO), this hybrid nanostructure exhibited strong peroxidase-like catalytic activity toward 3,3', 5,5'-tetramethylbenzidine (TMB) substrate in the presence of H2O2. Colorimetric determination of H2O2, indicated by the blue color of the oxidized TMB within 1 min, was observed using the Au@PtNP/GO nanozymes. To demonstrate practical application of the nanozymes, the Au@PtNP/GO microbeads were packed into a film-based electrochemical point-of-care (POC) device for sensitive and rapid H2O2 detection. Upon introduction of TMB substrate solution containing H2O2, the catalytically oxidized TMB was electrochemically reduced on the electrode surfaces, resulting in a broader detection range of H2O2 (1 mu M-3 mM) and a lower LOD (1.62 mu M) than achievable with the colorimetric detection method. Moreover, the developed POC devices showed the capability of accurate determination of H2O2 with strong repeatability and reproducibility in real sample test using artificial urine.