Application Research On The Construction Of Self-Powered Sensing Platforms Based On Photocatalytic Fuel Cell And Signal Amplification Technology

The fuel cell-based self-powered sensing system has become an indispensable sensing technology,and is also the general trend of sensing development at present.It has many advantages such as no need for external power supply,fast response speed,reasonable cost,easy construction of portable,miniaturized,wearable and implantable devices,etc.It has been widely used in biochemical analysis,food analysis and environmental pollution detection and other fields.Among several types of fuel cells,photocatalytic fuel cell(PFC)has aroused much research interest in recent years due to their combined advantages of photocatalysis with electrochemical analysis.In order to improve the performances of various aspects of the PFC-based sensor system,in this thesis,we constructed three types of photoelectrochemistry analysis methods under two-electrode systems by designing high-performance and diversified PFCs,combining different specific recognition elements and signal amplification technologies.These strategies realized the amplified and sensitive detection of different targets.The main research contents of this paper are as follows:(?)A PFC coupling with competitive immunoassay was designed for self-powered sensing of platelet derived growth factor-BB(PDGF-BB).In the PFC,the effective oxidation of ascorbic acid(AA)on a graphitic C₃N₄ nanosheets-nitrogen doped reduced graphene oxide-layered Mo S₂ modified photoanode under visible light illumination,and catalytic reduction of[Fe(CN)₆]^3-on a sulfur and nitrogen co-doped reduced graphene oxide modified cathode generated electrical output.In order to realize the specific detection of PDGF-BB,the antibody of PDGF-BB(Ab)was immobilized on photoanode to act as the recognition element.Meanwhile,a bioconjugate,dopamine-melanin nanospheres@Au NPs@PDGF-BB,was used as the competitive element of target which could dramatically reduce the output of PFC by blocking the transfer of AA to the photoanode.When the target PDGF-BB coexisted with the bioconjugate,the competitive binding of smaller target molecule with Ab immobilized on photoanode could reduce the binding amount of bioconjugate and induce an elevated output of PFC.Under the optimum condition,the output of PFC was linearly proportional to the logarithm of PDGF-BB concentration from 20 pg m L^-1 to 200 ng m L^-1,with a detection limit of 6.2 pg m L^-1(3?).Moreover,the developed self-powered competitive immunosensor was successfully applied to the detection of PDGF-BB in human serum.(?)A PFC-based self-powered sensing system with enhanced sensitization effect of CdS quantum dots(QDs)for sensitive detection of human T-lymphotropic virus type II DNA was constructed.The electrical output of the PFC is generated by the photooxidation of AA catalyzed by graphene composite Mo S₂ modified photoanode,while the reduction of oxygen catalyzed by Pt cathode.The target DNA can be specifically recognized and immobilized on the photoanode by two complementary strands of capture probe DNA and QDs-labeled report DNA,which enables the sensing system to possess excellent selectivity.A signal-on DNA analysis strategy was designed based on the amplification effect of sensitized CdS quantum dots.The sensor has a linear relationship with the response signal of PFC in the DNA concentration range of pmol L^-1 to 100 nmol L^-1,with a low detection limit of 15 fmol L^-1(3?),and shows a good stability,reproducibility and anti-interference ability.This study provides a promising idea for the construction of a self-powered gene analysis platform to monitor DNA activity and diagnose DNA-related clinical diseases.(?)A membraneless,single-chamber PFC with two photoelectrodes was combined with a capacitor to develop a portable self-powered sensor for sulfadimethoxine(SDM)detection.The PFC was comprised of a graphitic-C₃N₄ covered CdS photoanode and a Cu Br photocathode,which could generate suitable power output under visible light illumination to drive the sensing process.The biphotoelectrode system not only avoided the costly Pt cathode,but also exhibited enhanced electrical output efficiency.Moreover,a miniature capacitor was incorporate into the PFC to further amplify the output,and the short circuit current was recorded with a portable digital multimeter instead of traditional bulky electrochemical workstation.Taking the advantage of the increased output of PFC by SDM interacted with aptamer immobilized,which in ture was further photocatalytically oxidized on the photoanode,a signal-on aptasensor was achieved.The sensor showed a linear response to the logarithm of SDM concentration from 0.1 to 500nmol L^-1,with a detection limit of 57 pmol L^-1(3?).The sensitivity of the proposed sensor was 9.05 times of that without using a capacitor amplifier circuit.And it has been successfully applied to the assay of SDM in veterinary drug samples with desirable accuracy and precision.