Dual-Mode Of Colorimetric-Electrochemical Sensor Based On Nanozymes For Determination Of Dopamine And Uric Acid

Carbon-based composites containing different metals were prepared by different methods to investigate whether they have intrinsic enzyme-like catalytic and electrocatalytic activities,as well as their affinity for substrates and catalytic reaction mechanisms.Based on nanozymes with enzyme-like activity,the colorimetric and electrochemical dual-mode sensors for the sensitive determination the concentration of biomolecules（Dopamine or Uric acid）was constructed.The main contents are listed as follows:（1）The multi-walled carbon nanotube material containing cobalt and nitrogen co-doping was produced by a simple two-step pyrolysis method using cobalt acetate tetrahydrate,melamine and glucose as raw materials.Meanwhile,the pyrolysis temperature during synthesis was optimized obtain the nanozymes with the best catalytic activity which was further used to construct a colorimetric and electrochemical dual-channel sensor for the quantitative analysis of dopamine（DA）.When the pyrolysis temperature was 800℃,the materials（Co NC-800）had the best catalytic performance,and showed oxidase-like activity.The colorimetric sensing platform based on Co NC-800 was constructed to detect DA,and the limit of detection（LOD）was 0.88μmol/L.In addition,the electrochemical sensing platform based on Co NC-800/GCE has a low LOD of 0.05μmol/L for the detection of DA.（2）The multilayer carbon nanosheet material containing copper and nitrogen co-doping was produced by the two-step pyrolysis method using copper acetate monohydrate,melamine and glucose as raw materials.In addition,the effects of different doping conditions on the catalytic activity of the materials were studied.Finally,the material with the best catalytic performance was used to construct a platform for colorimetric and electrochemical dual-mode analysis of uric acid（UA）.The doping of copper（Cu NCs-800）enhanced the catalytic activity of the material and exhibited peroxidase-like activity.The colorimetric and electrochemical sensors constructed based on Cu NCs-800 was used for UA detection with LOD of 1.55μmol/L and 0.51μmol/L,respectively.（3）A composite material（Mn O₂@G）composed of manganese dioxide nanoparticles and graphene nanosheets was prepared by a modified Hummers and experimental post-processing method.A colorimetric and electrochemical dual-mode sensor based on Mn O₂@G was constructed for the detection of dopamine.The Mn O₂@G composites had excellent oxidase-like activity.A colorimetric and electrochemical dual-mode sensor based on Mn O₂@G was constructed for the detection of DA with LOD of 0.14μmol/L and 1.16μmol/L,respectively.It has been shown that different metal doping is the main factor that carbon-based nanozymes exhibit different intrinsic enzyme-like activities.In addition,the combination of metal and carbon allows the composite to have both enzyme-like activity and electrocatalytic activity.The results of this study make a positive exploration for the application of nanozymes in the field of colorimetric and electrochemical sensing.