Detection Of Disease Markers By Photoelectrochemical Sensors Based On Carbon/Semiconductor Composite

Disease markers are playing an increasingly important role in assessing cancer risk,improving prognosis and evaluating biotherapeutic response.Early and sensitive detection of disease markers can improve the treatment efficiency of many diseases.At present,many methods for detection of disease markers have been developed.Therefore,it is urgent to develop rapid,highly sensitive and highly specific methods for the detection of disease markers.Photoelectrochemistrybiological analysis is a promising and low-cost analytical method.PEC biosensing has attracted extensive attention because of its ability to detect biomolecules through photocurrent generated by oxidation of biomolecules.The research work of this paper focuses on the detection of disease markers by photochemical sensors based on carbon/semiconductor composite materials.Cadmium sulfide quantum dots and carbon nano-material were used as anode photoelectrochemical sensing analysis platform and the iodide-iodine oxide combined with carbon nanotubes as cathode photoelectrochemical sensing analysis platform,which realized the detection of nucleic acid,protein and enzyme with high sensitivity and high selectivity.The work of this paper includes the following five aspects:（1）Firstly,the principle,mechanism,types and applications of photoelectrochemical biosensor were introduced.Secondly,the research progress of carbon based nano-composite materials and photoelectrochemical biosensor based on carbon/semiconductor nano-composite materials were briefly described.Finally,the significance and main contents of this paper were proposed（2）Mi RNA detection by a"sandwich"photoelectrochemical sensor based on graphene-cadmium sulfide and grapdiyne oxide nanosheets.In this work,a novel mi RNA sensor was constructed by using an important cancer marker mi RNA-21 as a model target,the prepared graphene-cadmium sulfide quantum dots as photochemical sensing platform,and graphene-oxide connected to DNA probes as photocurrent signal inhibitors.Graphdiyne-cadmium sulfide quantum dot complex was synthesized by one-step hydrothermal method.Due to the poor conductivity of the graphdiyne oxide nanosheets connected DNA probe,the photoelectron transfer can be inhibited,thus the photocurrent signal was resuced.Sensitive and accurate detection of mi RNA-21 was achieved.（3）Detection of prostate specific antigen by photoelectrochemical immunosensor based on reduced graphene oxide and cadmium sulfide complex（r GO-CdS）.In this work,r GO-CdS complex and grapdiyne oxide nanosheet/horseradish peroxidase complex were prepared.Due to the protective effect of grapdiyne oxide,the horseradish peroxidase fixed on graphite-oxide alkyne had excellent storage stability and catalytic activity.Then,by using r GO-CdS as photoelectrochemical sensing platform,graphene oxide nanosheet combined with horseradish peroxidase and secondary antibody as photocurrent signal inhibitors,prostate antigen as target,a stable and sensitive type"sandwich"photoelectrochemical immunosensor was constructed.It shows multiple signal suppression effect and excellent sensing and detecting performance.（4）Detection of terminal deoxynucleotide transferase by cathode photoelectrochemical sensor based on Ag-Ag I-CNTs and multisite chain replacement amplification.In this chapter,Ag-Ag I-CNTs complex was prepared by one-step solvothermal method,which showed excellent photoelectrochemical properties and good dispersion.In this design,Ag-Ag I-CNTs complex was used as a photocathode sensing platform,coupled with the amplification reaction of multiple site chain replacement on the surface.Ag-Ag I-CNTs could effectively transfer photoelectrons and promote the rapid reduction of photoelectron receptor[Fe（CN）₆]^3-.The sensor showed a wide linear response range and a low detection limit for Td T activity.（5）Micro RNA detection by photoelectrochemical sensor based on BiOI-Bi/CNTs and cyclic chain replacement amplification.In this work,BiOI-Bi/CNTs composites were prepared.Compared with BiOI/CNTs,BiOI-Bi and BiOI,this material had greatly enhanced photoelectrochemical properties.Using BiOI-Bi/CNTs as photocathode material and cleverly cyclic chain replacement amplification reaction,a novel photocathode sensor was successfully constructed for the highly sensitive determination of mi RNA-let-7a.In this design,the cyclic chain replacement amplification method greatly reduced the complexity of the sensing system and simplified the sensing operation by using a single hairpin probe.The photocathode avoid the interference of biological samples.K₃[Fe（CN）₆]as the photoelectron receptor effectively absorbed the photoelectrons generated by the excitation of BiOI-Bi/CNTs,which furtherly enhanced the photocurrent signal changes.