Investigation Of Electrochemical Biosensors Based On Cobalt-series Metal-Organic Frameworks

ZIF-67 is a typical cobalt-series metal organic frameworks,which has excellent properties such as stable chemical and physical properties,multiple catalytic active sites,high conductivity,high specific surface area,controllable pore structure,etc.It has been applied in the fields of adsorption,environmental protection and catalysis.Electrochemical biosensor technology is an easy-to-use,automatic,small,low-cost,rapid,sensitive,selective analysis method,and it has been widely used in biology,medicine,chemistry and physics fields.Due to the well electrochemical performance of ZIF-67,two metal organic framework derived composites were prepared in this work: Au@NC@GC and Au@GC@HRP composites.Au@NC@GC composites were composed of nitrogen-doped carbon(NC)encapsulating Au NPs as core and graphitic carbon(GC)as shell.Au@GC@HRP composites were formed from Au@GC adsorption and fixation of horse radish peroxidase.NC and GC was prepared from ZIF-8 and ZIF-67 crystal with thermal treatment in nitrogen,respectively.The microstructure of composites was characterized by SEM and TEM,and the valence state and component analysis were further investigated by Element Mapping and XPS.Electrochemical impedance spectroscopy(EIS),cyclic voltammetry(CV),differential voltammetry pulse(DPV),and Amperometric i-t curves were also recorded,showing a better chemical performance of the composites than their constituent composites and suitability for electrochemical biosensor technology.On this basis,two electrochemical biosensors modified by composite materials on glassy carbon electrode,Au@NC@GCGCE and Au@GC@HRP-GCE,were constructed.The further research showed that Au@NC@GC-GCE can monitor dopamine and uric acid simultaneously,and Au@GC@HRP-GCE can detect hydrogen peroxide accurately and effectively.Both of them exhibited high sensitivity,low detection limit,wide linear range,strong antiinterference ability,good stability,reproducibility and repeatability.In biological experiment,Au@NC@GC-GCE monitor UA and DA successfully in serum,while Au@GC@HRP-GCE detect hydrogen peroxide in cells qualitatively and quantitatively.These results verified the possibility for their future promising applications in clinic samples analysis.