Study On New Methods Of Functional Nanomaterials-based Photoelectrochemical Bioanalysis

As a new detection technology based on the photoelectrochemical(PEC)process,PEC bioanalysis features simple equipment and low background noise,and is becoming a promising analytical methodology.However,due to the short development time,some important challenges still remain in the construction of ultrasensitive PEC bioanalysis.For example,new type of highly efficient photoelectric functional interface and the novel signaling mechanisms still need to be exploited.To address these problems,based on the development of new functional materials in the preparation of photosensitive electrodes and the construction of sensitive signal sensing strategy and other applications,a series of reseach works had been carried out as described below.1.Bismuth oxyiodide couples with glucose oxidase:a special synergized dual-catalysis mechanism for photoelectrochemical enzymatic bioanalysisOn the basis of a special synergized dual-catalysis mechanism,this work reports the preparation of a Bi OI-based heterojunction and its use for cathodic photoelectrochemical(PEC)glucose biosensing which,unexpectedly,revealed that hydrogen peroxide(H₂O₂)had a greater impact than dioxygen(O₂).Specifically,the Bi OI layer was in situ formed on the substrate through an impregnating hydroxylation method for the following coupling with the model enzyme of glucose oxidases(GOx).The constructed cathodic PEC enzyme sensor exhibited a good analytical performance of rapid response,high stability,and good selectivity.Especially,This interesting phenomenon was attributed to a special synergized dual-catalysis mechanism,and the photoelectric functional material of Bi OI can also act as the peroxidase mimetics.2.Semiconducting Cu O nanotubes:synthesis,characterization,and bifunctional photocathodic enzymatic bioanalysisThis work reports the synthesis,characterization,and application of bifunctional semiconducting Cu O nanotubes(NTs)electrode for innovative synergized cathodic photoelectrochemical(PEC)enzymatic bioanalysis.Specifically,Cu O NTs electrode wa s fabricated by surface oxidation of the copper foil in an alkaline aqueous solution with(NH₄)₂S₂O₈and then annealed in air.After the subsequent coupling with the model enzyme of xanthin e oxidase(XOD),the resulted photocathodic enzyme biosensor exhibited good analytical performance of rapid response,high stability,and good sensitivity.Especially,due to the unique catalytic property of Cu O toward H₂O₂,a novel enzymatic cascade design between biological catalyst(XOD)as natural enzyme)and biomimetic catalyst(Cu O as the peroxidase mimetics)was constructed,and the dual-catalyst system with special synergy effect could achieve the cathodi c PEC guanine bioanalysis with enhanced efficiency.In the determination,the cathodic photocurrent was found to be proportional to the guanine concentration,which was different from the commonly observed O₂-dependent suppression of the photocurrent.3.Ag nanoclusters could efficiently quench the photoreszaiponse of Cd S quantum dots for novel energy transfer-based photoelectrochemical bioanalysisHerein the influence of ultrasmall Ag nanoclusters(NCs)against Cd S quantum dots(QDs)in a photoelectrochemical(PEC)nanosystem was exploited for the first time,based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the Cd S QDs.In a model system,DNA assay was achieved by using molecular beacon(MB)probes anchored on a Cd S QDs modified electrode,and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulate d Ag NCs.After the MB probe was unfolded by the target DNA sequence,the labels of oligonucleotid e encapsulated Ag NCs would be brought in close proximity to the Cd S QDs electrode surface,and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs.Thus,by monitoring the attenuation in the photocurrent signal,an elegan t and sensitive PEC DNA bioanalysis could be accomplished.The developed biosensor displayed a linear range from 1.0 p M to 10 n M and the detection limit was experimentally found to be of 0.3p M.4.Gold nanoparticles-induced photocurrent quenching and recovery of polymer dots:toward signal-on energy-transfer-based photocathodic bioanalysis of telomerase activity in cell extractsUsing the innovative polymer dots(Pdots)-involved ET,this work reports the first signal-on and cathodic PEC bioanalysis toward telomerase(TE)activity in cell extracts.Specifically,the sequential binding of capture DNA(c DNA),telomerase primer sequence(TPS)and Au NPs-labeled DNA probe(ADP)on the electrode would place the Au NPs in close proximity of Pdots,leading to obvious quenching of the cathodic photocurrent.The subsequent extension of the TPS by TE in the presence of deoxyribonucleoside triphosphates(d NTPs)would then release the ADP from the electrode,leading to the recovery of the photocurrent.On the basis of the Au NPs-induced photocurrent quenching and recovery of Pdots,a sensitive biosensor could thus be developed by tracking the photocurrents to probe the TE activity.This strategy allows fo r signal-on and cathodic PEC bioanalysis of TE,which can be easily extended for numerous other targets of interest.