Construction And Application Of High Performance Self-powered Sensing Device Based On Enzymatic Biofuel Cells

Typical electrochemical sensors almost need external power source,which limits their widely application.Enzymatic biofuel cells have the ability to directly convert chemical energy to electrical energy by using enzymes as catalysts,and generate sustainable energy under mild conditions,which is beneficial to miniaturization and portability of equipment.Compared with traditional electrochemical sensors,enzymatic biofuel cells based self-powered sensing device can realize rapid and portable on-site assay and reduce the costs.The enzyme-loading quantities and electron transfer rate are the key factors affecting the performance of enzymatic biofuel cells.Nanocomposites have the characteristics of large specific surface area,high conductivity and good biocompatibility.They have been widely used in self-powered sensors based on enzymatic biofuel cells.The introduction of an energy harvesting device can further increase the sensitivity of the self-powered sensor.The main work of this dissertation is to build high-performance self-powered electrochemical sensors based on enzymatic biofuel cells and biological amplification technologies for the highly sensitive detection of biomolecules,and introduce supercapacitor to further improve the sensitivity.The main contents are as follows:?1?A novel self-powered electrochemical sensing platform was assembled for the sensitive detection of L-cysteine based on a one-compartment glucose/air enzymatic biofuel cell.The ultrathin hollow carbon shell/gold nanoparticle composite was used as the electrode material of enzymatic biofuel cell,which could significantly enhance electron transfer and improve the sensitivity of the self-powered sensor.DNA bioconjugate was designed to increase the loading of bioanode enzymes.In the presence of Ag⁺,the DNA bioconjugate containing glucose oxidase was immobilized on the surface of the anode.When L-cysteine was present,since L-cysteine and Ag⁺could form an insoluble thiolate,the DNA bioconjugates containing glucose oxidase fell off from the bioanode,and the open circuit voltage significantly reduced.So the quantitative determination of L-cysteine was achieved by the changes of the open circuit voltage.Under optimized condition,the linear range of the constructed sensor was 10 nmol/L-5?mol/L with the detection limit of 2.20 nmol/L.This method displayed a good selectivity and could be used for the detection of L-cysteine in human urine.?2?A highly sensitive self-powered miRNA sensor was constructed based on a one-compartment enzymatic biofuel cell combined with cruciform DNA.Sulfur-selenium co-doped graphene/gold nanoparticles was used as the cathode and anode substrate materials,and the glucose oxidase was immobilized on the surface of the anode by a condensation reaction between terminal amino groups on the lysine residues of enzyme and carboxyl groups on the AuNPs to obtain a bioanode.When the target was present,the loop structure of the capture probe immobilized at the cathode was opened,and the end of the capture probe could hybrid with the cruciform DNA containing an electron acceptor(i.e.Fe?CN?₆^3-),and then the hybrid was immobilized on the surface of the cathode.Glucose oxidase then catalyzed the oxidation of glucose to produce electrons,which reduced Fe?CN?₆^3-to Fe?CN?₆^4-,and produced an electrical signal.As the concentration of miRNA-21 increased,the open circuit voltage gradually increased,and a new method for sensitive detection of miRNA-21 was established.The linear range of the new method was 0.5-10000 fmol/L,and the detection limit was 0.15 fmol/L.The sensor did not require an external power supply and had a high sensitivity,and can be used for real sample detection.?3?The carbon nanotube/gold nanoparticle composite with bilirubin oxidase and tin disulfide/gold nanoparticle with glucose oxidase were respectively used to construct the anode and cathode of biofuel,and a novel protein self-powered sensing device was then assembled by further combined with aptamers.When thrombin was present,the bioconjugate was immobilized on the surface of the anode to form an aptamer-target-aptamer sandwiched structure,and then catalyzed glucose oxidation to increase the open circuit voltage of the sensor.Under the optimized condition,the linear range of the sensor was 0.02 ng/mL-5 ng/mL,and the detection limit was 7.90 pg/mL?0.22 pmol/L?.This strategy was successfully applied to detect the thrombin in human serum samples.In order to further improve the sensitivity of the self-powered sensor,a supercapacitor was introduced to construct a capacitor/enzyme biofuel cell hybrid device,which significantly increased the current response signal and improved the detection sensitivity.