A Study Of Biological Oxygen Reduction Cathode Based On Small Laccase

With the development of the society,environmental pollution has received more and more attention from all over the world,and clean energy has become a hot topic of current research.In the research of clean energy utilization,biofuel cell has attracted wide attention because of its high efficiency and low pollution.In the research of biofuel cell,the catalytic efficiency of oxygen reduction on biocathode is one of the important restricting factors.Therefore,it is particularly important to construct the biocathode interface.In the field of environmental pollution control,biosensors have received extensive attention because of their high sensitivity and low cost.From the development history of bioelectrochemical sensors,the research of each generation of biosensors is inseparable from the construction of stable electrode surfaces.Therefore,the construction of an efficient and stable biocathode interface can not only provide a reference for the development of biofuel cells,but also contribute to the research of bioelectrochemical sensors.Based on this situation,we compared the advantages and disadvantages of indirect electron transfer and direct electron transfer,and we combined that with the characteristics of small laccase.After that,we selected carbon nanomaterials as electrode materials for its good biological compatibility and electrical conductivity,and determined the experimental scheme for the construction of direct electron transfer interface.We explored and optimized the expression and purification conditions of recombinant small laccase,and achieved the mass preparation of active small laccase(2.1476U/mg).The structural characterization results of related proteins showed that this recombinant small laccase retained the complete structure of the negative dimer with copper ion as the active catalytic site,with particle size ranging from 6 to 7 nm.After the characterization of the small laccase,the oxygen reduction catalytic effects of carbon modified enzyme electrodes were compared.The results showed that the catalytic activity of the carbon modified enzyme electrode with higher surface curvature was significantly stronger than that of the carbon modified enzyme electrode with lower surface curvature with the same amount of modification of 10 ?L(1mg/mL).The response strength(0.85 A,0.08 V vs.Ag/AgCl)of the SWCNT-SLAC electrode was about 3 times that of the Graphene-SLAC electrode(0.25 A,0.11 V vs.Ag/AgCl).In the further mechanism study,we used Laviron equation to calculate the direct electron transfer rate between the surface of small laccase and carbon materials,and quantitatively analyzed the molecular orientation of small laccase on the surface of different carbon materials by ATR-FTIR spectroscopy.Finally,we established a model of direct electrocatalytic behavior of small laccase controlled by surface curvature of carbon nanomaterials.In other words,by enhancing the hydrophobic interaction with the hydrophobic cavity containing T1 Cu in SLAC and complementing the surface structure,the good docking ratio between SLAC and the conductive surface can be improved,and the distance between the conductive surface and the active copper site can be shortened,and the direct electron transfer speed can be accelerated.Correspondingly,the interaction between large diameter or planar carbon material and SLAC is weak,which makes it easy to form disordered orientation.The direct electron transfer rate and catalytic current decrease due to alignment.This model provides a new idea and method for the design and construction of bioelectrochemical interface based on carbon nanomaterials.