Novel Photoelectrochemical Biosensor: Fabrication And Application

Photoelectrochemical(PEC)biosensing is a new kind of sensor,which is based on the combination of Photoelectrochemical technology and biological recognition,this technology has the advantages of low background signal,high sensitivity,simple device.Compared with other analytical methods,photoelectrochemical biosensor has become an important technique in the field of biological analysis.In this thesis,highly sensitive photoelectrochemical biosensors were constructed by using different optoelectronic materials.In the first chapter,the photoelectrochemical method was reviewed.The basic principles and the fabrication process of photoelectrochemical biosensor were introduced.The photoelectrochemical biosensors were classified according to the different detection target.At last,the main content of this thesis was presented.In the second chapter,we describe the preparation of graphene-cadmium sulfide-doped manganese nanocomposites and their application in photoelectrochemical detection of cysteine.Graphene has a large specific surface area and can load more cadmium sulfide.The results show that the nanocomposites have good detection performance.In the third chapter,sensitive DNA biosensor was fabricated by using inorganic-organic nanocomposites cosensitization combined with ?-Exonuclease assisted target recycling.?-Exo could cut the helper DNA(hDNA)in double stranded of h DNA/ target DNA(tDNA),and the tDNA was released,the remaining hDNA sequence could hybridize with probe DNA modified inorganic-organic nanocomposites,and realize the cosensitization of electrode.The dual signal amplification biosensor provides a new analytical platform for the detection of DNA.In the fourth chapter,based on enzyme assisted recycling,hybridization chain reaction and ALP enzyme catalytic reaction,the sensitive DNA photoelectrochemical biosensors was fabricated.Firstly,the RGO was deposited on the electrode,after the modification of CdS nanocrystals and ZnS nanocrystals,then the capture probe was fixed,after incubated in the solution containing phosphate group modified DNA,the reaction solution of target and ? exonuclease in a period of time,the capture probe DNA on electrode was hybridized with the output DNA,then photocurrent further increased by hybridization chain reaction,finally according to the affinity of biotin and avidin,ALP catalyzed AAP to produce AA which provides electrons.The experimental results show that the photoelectrochemical sensor can realize the ultra sensitive detection of DNA.