Studies On Photoelectrochemical Biosensor Based On Perylene And Signal Amplification

Photoelectrochemical（PEC）biosensor is a kind of sensor which converts the physical,chemical and biological interaction between photoactive substance and target analyte into photocurrent signal by the specific recognition between photoactive substance and target,and then achieves the quantitative detection of target.PEC biosensor has attracted much attention in analysis due to their advantages of simple operation,high sensitivity,rapid response and good selectivity.This paper mainly takes the photoelectric active material perylene series as the immobilized matrix,combined with a variety of efficient signal amplification technologies（DNA self-assembly,nanomaterial simulation enzyme catalysis function,DNA circulation）to build a high-sensitivity PEC biosensor to achieve trace analysis of proteins and metal ions.The main contents include the following aspects:1.PEC biosensor based on methylene blue（MB）embedded three-dimensional DNA（3D DNA）networks sensitized 3,4,9,10-perylene tetracarboxylic acid（PTCA）Methylene blue（MB）,an organic dye,has a wide light absorption range and can effectively sensitize PTCA to obtain a higher photocurrent signal.Therefore,we constructed a sensitive PEC biosensor by using PTCA as immobilized matrix,combined with DNA self-assembly technology to obtain MB embedded 3D DNA network for quantitative analysis of lead ions(Pb²⁺).In which,the 3D DNA networks containing multiple double-stranded（ds）DNA formed by enzyme-free self-assembly can be used as a sensitizer carrier to increase the loading amount of MB,and effectively enhance the photocurrent signal of PTCA.The preparation method of the PEC biosensor is simple and effective,and opens up a new direction for the subsequent organic dye-sensitized PEC biosensor.2.Manganese porphyrin（MnPP）both as horseradish peroxide（HRP）mimetic enzyme and PTCA quencher to construct PEC biosensorThe sensitivity of“signal off”PEC biosensor mainly depends on the degree of reduction of photocurrent signal after target recognition.However,the existing“signal off”PEC biosensors generally use a single method of steric hindrance,photoactive material consumption,and energy transfer to achieve signal reduction,which greatly limit the increase in sensitivity.Therefore,a novel PEC biosensor was constructed based on MnPP as both HRP mimic enzyme and quencher of PTCA.First,we used PTCA as a photoactive material and modified it on the surface of the electrode to obtain an extremely high initial photocurrent signal.The 3D DNA networks structure formed by DNA self-assembly is then modified to the electrode surface by a typical sandwich reaction.Since MnPP can be inserted into dsDNA,a large amount of MnPP can be embedded in the 3D DNA networks nanostructure.We found that MnPP can not only quench the PTCA photocurrent signal,but also simulate the HRP enzyme catalyzed rapid precipitation on the electrode to further reduce the photocurrent signal,thereby obtaining a double-reduced PTCA photocurrent signal and improving the sensitivity of the sensor.Therefore,the usage of a material with multiple functions,overcoming the limitations of using a single function or the complicated and cumbersome operation brought by the simultaneous usage of multiple substances,it opens up a new way for highly sensitive biological monitoring.3.A wavelength-resolved two components simultaneous detection PEC biosensor at a single interface based on sensitization/quenchingMulticomponent simultaneous detection at the same interface can effectively improve the analysis efficiency,shorten the analysis time and increase the analysis flux.In this paper,based on the effect of sensitizer MB and quenching agent ferrocene（Fc）on perylene-3,4,9,10-tetracarboxylic dianhydride（PTCDA）at specific wavelength,a PEC biosensor with simultaneous detection of two targets on the same interface was skillfully constructed.Specifically,the DNA fragments marked by Fc or MB cut by Mg²⁺or Pb²⁺were adsorbed on the surface of the electrode by host-guest recognition,thus affecting the photocurrent signals of PTCDA at different light wavelengths,and then the concentration of Mg²⁺and Pb²⁺can be quantitatively analyzed by calculation.The strategy skillfully distinguishes the signal changes caused by different targets at the same interface,and the target is not limited to metal ions,but can be used for simultaneous analysis of proteins,DNA,and miRNA so on.