Construction And Applications Of New Photoelectrochemical Biosensors Based On N-types Of Semiconductor Nanomaterials

Photoelectrochemical?PEC?bioanalysis has made rapid progress in the field of life analytical chemistry due to high sensitivity,fast response and low cost,which inherits electrochemical bioanalysis of advantages and the total separation of the two energy forms as excitation source and detection signal.For PEC immunoassays,quantitative detection is generally achieved by photoelectron transfer at the electrode/electrolyte interface and changes in photocurrent after immune recognition.Complexity of actual biochemical samples,especially the low abundance of some disease markers in the early detection stage of the disease,put forward high requirements for PEC biosensing analysis.It is an important goal in improving sensitivity for the pursuit of analytical chemistry.High photoelectric conversion efficiency and signal amplification strategy play an important role in the development PEC sensitive immunoassay systems.Therefore,finding photoactive nanomaterials with excellent performance and exploring new sensing recognition strategies have been very active research fields for the development of PEC biosensors.In this paper,nanomaterials with excellent PEC preformance were synthesis.Combination of predominant biosensing strategies,the proposed PEC biosensors have found to provide a sensitive and specific strategy for detection of disease markers.The main innovations and research contents are as follows:1.A novel PEC sensor for sensitive detection of myoglobin?myo?was constructed based on ternary composite of g-C₃N₄-MoS₂@CdS:Mn modified photoelectrodes coupled with CuO as signal amplification tags.The co-sensitive materials of g-C₃N₄-MoS₂@CdS:Mn could effectively promote the electron transfer and evidently restrain the recombination of electron-hole pairs,producing the high photocurrent response.To proof the performance of the co-sensitized structure in PEC bioanalysis,a sandwich type PEC immunosensor was designed by using the co-sensitized structure as photomatrix,Myo as model protein,and anti-Myo-CuO conjugates as amplifying tags.The introduction of anti-Myo-CuO conjugates in this system could significantly quench the PEC response of the sensing interface owing to the competition of the light-generated electron,poor conductivity and steric hindrance of the anti-Myo-CuO conjugates.In virtue of synergistic amplification of the CdS:Mn sensitized heterostructured g-C₃N₄-MoS₂ and the anti-Myo-CuO conjugates,the immunosensor could respond down to 0.42 pg/mL Myo with a detectable range of 1.0pg/mL to 50 ng/mL.Furthermore,the method has been successfully applied to the detection of Myo in human serum samples,and the results consistent with Xinyang Central Hospital.The recoveries were between 90.0%and 107.0%with the RSDs no more than 6.3%.2.A novel potentiometric-resolved PEC biosensor for the multiplexed detection of cardiac biomarkers was reported by modulating the bias potential in the detection process.CdS nanowires?NWs?and SnNb₂O₆ nanosheets?NSs?with different critical voltage were screened,and based on which a potentiometric resolved system was introduced into the PEC biosensors.With the change of the bias voltage,anodic current from CdS NWs and the cathodic current from SnNb₂O₆ NSs can be well distinguished.To proof the applicability of this potentiometric resolved system in PEC multi-biomarkers analysis,a label free PEC immunosensor was constructed for the detection of two cardiac biomarkers,myoglobin?Myo?and cardiac troponin I?cTnI?.Due to the eminent potential resolution and excellent PEC properties of the photoactive materials,the designed biosensor displayed a high sensitivity for Myo and cTnI detection.The linearity for cTnI and Myo are both from 5.0 pg/mL to 50 ng/mL,with detection limits of 2.0 pg/mL for Myo and 2.5 pg/mL for cTnI,respectively.Moreover,the method has been successfully applied to the detection of Myo and cTnI in human serum samples,and the results consistent with Xinyang Central Hospital.The recovery for Myo detection ranged from90.0%-112.0%with RSDs no more than 6.3%,whereas the data for cTnI detection are in the range of 90.0%-115.0%with RSDs no more than 6.8%.3.To combine the advantages of photoanode-based biosensor and photocathode-based biosensor,a feasible photoanode-photocathode PEC biosensor was fabricated for detection of cTnI based on exciton-plasmon interaction?EPI?,steric resistance effect and electron receptor consumption triple signal amplification strategy.In this system,photoanode of SnNb₂O₆-MoS₂ modified ITO was used as auxiliary electrode while photocathode of CuBi₂O₄-rGO/ITO electrode was selected as working electrode,which shows the outstanding advantages consisting of high sensitivity and good anti-interference ability.In the presence of targets,Au@Ag NPs-anti-cTnI-CAT was introduced.Via the synergetic effect of EPI,steric resistance effect and electron receptor consumption,the electron conduction and the rate of electron transfer can be inhibited,hence the photocurrent signal can be changed.Under optimized conditions,the biosensor played a preferable linear range from 5.0pg/mL to 0.1?g/mL and the limit of detection is 2.0 pg/mL.Besides,the method has been successfully applied to the detection of cTnI in human serum samples,and the results consistent with Xinyang Central Hospital.The recovery for cTnI detection ranged from 90.0%-115.0%with RSDs less than 7.6%.4.In this work,luminol,horseradish peroxidase?HRP?,and anti-cTnI were first immobilized rGO-Au?rGO-Au-luminol@HRP-anti-cTnI?,which showed prominent chemiluminescence activity.Based on CdS@g-C₃N₄ photoelectrode,a novel PEC immunosensor was constructed by using rGO-Au-luminol@HRP-anti-cTnI system as internal excitation light source to achieve cTnI sensitive detection.Based on HRP accelerated oxidation of luminol by H₂O₂ to yield the chemiluminescence,which will act as a light source to excite CdS@g-C₃N₄ composites to generate photocurrent signals.The sensitive split-type immunoassay was achieved.Under optimized conditions,the biosensor played a preferable linear range from 5.0 pg/mL to 50ng/mL and the limit of detection is 2.2 pg/mL.Besides,the method has been successfully applied to the detection of cTnI in human serum samples,and the results consistent with Xinyang Central Hospital.The recovery for cTnI detection ranged from 80.0%-111.0%with RSDs less than 6.2%.