Electrode Materials For Enzymatic Biofuel Cell And Enzymatic Biofuel Cell-Based Self-Powered Biosensor

Enzyme biofuel cells(EBFC)have attracted great attention because they can convert chemical or biochemical energy to electricity by making use of body fluids.Compared with conventional fuel cell,EBFC have many advantages,such as abundant fuel,environmental friendly,operation at ambient temperatures and neutral pH,etc.Currently,the development of EBFC focuses on employing new materials to improve the cell performance as well as constructing novel applications in self-powered sensors.The main contents are as follows:1.A Fe3O4-carbon nanofiber/gold nanoparticle hybrid for enzymatic biofuel cells with larger power outputEnzymatic biofuel cells(EBFCs)are considered as a promising approach to meet the requirements of power sources.Electrode materials,which are significant factors to affect the power output of EBFCs,have aroused great interest.Herein,we developed an EBFC using a Fe3O4-carbon nanofiber/gold nanoparticle hybrid as the substrate electrode for improving the performance of the power output.The open-circuit voltage(Eocv)of the designed EBFC reached 0.68±0.03 V,and the maximum power density(Pmax)reached 126±4.5 mW cm2.The as-prepared EBFC showed 3 times higher Pmax compared to the EBFC based on the carbon nanofiber/gold nanoparticle hybrid,which was ascribed to the good electrocatalytic activity of Fe3O4 NP loaded carbon nanofibers(CNFs),the 3D porous structure of CNFs as well as the uniform distribution of Au NPs.The Fe3O4-CNF/gold nanoparticle hybrid is considered as a promising candidate for constructing electrochemical biosensors and biofuel cells.2.Ultrasensitive self-powered sensing for caspase-3 activity based on enzymatic biofuel cellsCaspase-3 is one of the most frequently activated cysteine protease used in the early stage of apoptosis.In this study,we have developed a one-compartment enzymatic biofuel cells(EBFCs)based self-powered platform for ultrasensitive and specific detection of caspase-3 activity.In the biocathode,bilirubin oxidase(BOD)was selected as the biocatalyst for enhancing O2 reduction.In the bioanode,glucose oxidase(GOD)was used for catalytic oxidation of glucose with O2 as the mediator.Moreover,graphene/gold nanoparticles(G/Au NPs)hybrid was employed as the substrate electrode,which could accelerate the electron transfer and enhance the bioelectrocatalysis reactions of enzymes.The biotinylated DEVD peptides were assembled on the substrate electrode by a Au-S bond between AuNPs and thiol group of the terminal cysteine residue.The BOD bioconjugate was obtained by linking BOD and streptavidin on carbon nanofibers/gold nanoparticles(CNFs/Au NPs)through a condensation reaction between amino groups in the protein structure and carboxyl groups on the Au NPs.Then,the BOD bioconjugate was immobilized on the peptide-functionalized substrate electrode via the specific interaction between biotin of the peptide and streptavidin.A one-compartment EBFC based self-powered biosensor,composed of a BOD bioconjugate-peptide-functionalized biocathode and GOD modified bioanode,was constructed for the detection of caspase-3 activity.When the biocathode was immersed in cell lysates containing active caspase-3,caspase-3 could specifically cleave the N-terminus of the tetrapeptide Asp-Glu-Val-Asp(DEVD),leading to a decrease amount of BOD bioconjugate on the biocathode.As a consequence,the reduced BOD loading on the biocathode would affect the catalytic performance towards O2 reduction and resulted in the lower power output of the EBFC.This effective strategy has great potential as a simple,ultrasensitive and portable tool in cancer research.