Research On Photoelectrochemical Properties And Biological Analysis Of Nanocomposites

Photoelectrochemical(PEC)biosensor,as a newly developed and powerful analytical method,provide a wide range of applications in the early diagnosis of diseases,environmental monitoring and food safety detection.PEC signals of the biosensor are used to detect specific biomolecules,and the PEC efficiency mainly depends on the properties of photoactive materials.Therefore,the PEC performance of the photoactive materials is an important factor affecting the biosensor.These photoactive materials including semiconductors,heterojunction and precious metal-based semiconductors have unique advantages in optical conductivity and magnetism,which have injected new vitality into the development of biosensors.In this paper,based on the study of PEC properties and biological analysis of nanocomposite materials,a variety of photoelectrochemical biosensing platforms have been established to realize the sensitive detection of trace nucleic acids and tumor suppressor gene P53.This work includes the following three parts.1.In this study,a novel versatile dendritical amplification photoelectric(PEC)biosensing platform using Bi₂S₃nanorods and perylene-based polymer(PTC-NH₂)as double signal probes is proposed for the detection of trace target DNA.Bi₂S₃nanorods as efficient photoactive materials were firstly immobilized on the ITO electrode,then Au nanoparticles(NPs)were modified on the electrode surface,and the ITO/Bi₂S₃/Au NPs generated a high PEC signal.At the same time,exonuclease III(Exo III)-assisted target recycling generated a large number of DNA product chains(PC),and PC hybridized with hairpin DNA(H1)on Au NPs/B₂S₃/ITO,then triggered rolling circle amplifification(RCA)and the hybridization chain reaction(HCR)to form the dendritic structure with abundant DNA duplexes.After large amounts ofMn(III)meso-tetra(N-methyi-4-pyridyl)porphine pentachloride(Mn PP)were embedded in the dendritic structure,they efficiently quenched the PEC signal,realizing the“signal off”detection of the target.In addition,the dendritic structure was also formed on the Au NPs/ITO,and large amounts of PTC-NH₂molecules as the PEC probe were inserted into the dendritic structure,achieving a highly enhanced PEC current for the“signal on”detection of the target.This biosensing platform with double signals exhibits good analytical performance and wide linear detection ranges.This study develops a new DNA nanostructure-amplified versatile PEC sensing platform for bioanalysis,showing promising potential for application in gene therapy and clinical analysis.2.In this study,a novel photoelectrochemical(PEC)“signal-on”biosensor based on Bi₂Sn₂O₇/Bi₂S₃heterojunction coupled with target-switchable DNA hydrogels was reported for ultrasensitive detection of P53 gene DNA.Sulfide ions are discovered for the first time to display excellent PEC sensitization effect on Bi₂Sn₂O₇material by forming Bi₂Sn₂O₇/Bi₂S₃heterojunction,not only the sensitization amplitude reached 63 times,but also the photocurrent polarity switched from cathodic to anodic.When target DNA induced-cycling amplification process produced a mass of product chains(PD),PD was introduced to the target-switchable DNA hydrogels to quantitatively release sulfide ions,which were further introduced to the Bi₂Sn₂O₇-modified PEC platform and formed heterojunction via anion-exchange reaction,resulting in enormous enhancement of PEC signal due to the significant sensitization effect of Bi₂Sn₂O₇/Bi₂S₃.The corresponding PEC signal change of the Bi₂Sn₂O₇/Bi₂S₃platform was used for detection of target DNA.This biosensing strategy opens a novel sulfide ions-sensitized PEC platform,and exhibits excellent analytical performance with wide linear range(100 fM-10 nM),which has broad application prospect in bioanalysis and clinical diagnosis.3.In this study,an innovative photoelectrochemical(PEC)biosensor based on a new BiVO₄/Ag₂S heterojunction combined with Exo III-assisted silver nanoclusters(NCs)amplification was reported for the detection of tumor suppressor gene P53.BiVO₄is a promising photosensitive material due to its strong visible light absorption,suitable band gap,and safety nontoxicity.However pure BiVO₄suffered from the rapid recombination of photogenerated carriers,which limited its photoelectric conversion efficiency.After Ag⁺was generated by target-induced silver NCs amplification reaction,Ag₂S was synthesized by ion layer adsorption reaction on the surface of BiVO₄to form the BiVO₄/Ag₂S heterojunction.Compared with the photocurrent of pure BiVO₄,the PEC sensitization of the heterojunction was 112times.The enhanced photocurrent signal could be used to realize the detection of suppressor gene P53.In addition,the linear detection range of this biosensor was 1fM-100 nM and the detection limit was 0.42 fM.So this work opened a new avenue for BiVO₄/Ag₂S heterojunction in biosensing applications and provided a new technology for the early diagnosis of tumors.