The Exploration About Photoelectrochemical Biosensor Based On Signal Amplification

Photoelectrochemical biosensor,a kind of detection device bases on the photoelectric conversion characteristic of photosensitive material for determing the concentration of the target.Because of its advantages of simple equipment,high sensitivity and easy operation,it was more and more used in the field of biological analysis.In this paper,several sensors were constructed based on different signal amplification strategies,which were used to detect target.1.An"on-off-on"trypsin PEC sensor was constructed by using PEI sensitized mesocrystalline TiO₂ as the matrix of photoactive and the synergetic inhibitory effect of Peptide@B-CQDs complex.The B-CQDs-containing peptide fragment was released from the electrode due to the trypsin`s specific cleavage of the spermonic acid site in the peptide chain and the photoelectric signal was enhanced.Based on this phenomenon,the sensitive detection of trypsin was realized,and the efficacy of trypsin inhibitor was evaluated;2.In this chapter,it was found that the peptide chain of a specific sequence is similar to that of zearalenone and could specifically bind to antibodies.On the basis of this,the peptide chain of specific sequence was labeled with tyramine functionalized rutile phase TiO₂ mesocrystals as photoactive probe.Because the functional peptide chain can compete with ZEN to recognize solid-phase antibodies,the partially tyrosine functionalized photoelectric probe is immobilized on the sensing interface.Under the catalysis of HRP,[ta-HRP]_n junction could be formed by combining the photoelectron probe with tyramine functionalized to the solid phase interface,which resulted in the increase of photocurrent and impedance at the same time.By recording the impedance and photocurrent of the sensing interface under different concentration of zearalenone,the sensitive detection of zearalenone could be realized,which provided a new non-toxic detection method for the separation and analysis of zearalenone;3.It was found that the composite of TiO₂-B-CS had the function of HRP like enzyme.A large amount of silver ions were immobilized on TiO₂-B-CS?TiO₂-B-CS@Ag⁺?via the enrichment of silver ions by chitosan.The photoelectric probe was prepared by functionalizing the composite material with antibody to prostate specific antigen.After the immune recognition reaction,the photoprobe could catalyze the oxidation of S₂O₃^2-to S^2-in the solution of H₂O₂ and Na₂S₂O₃,and then bound to the Ag⁺of probe to form Ag₂S.And the Ag₂S was matched at the TiO₂-B level,which promoted photoelectron transfer and improved the photoelectric response of the sensing system.Finally,the purpose of sensitive detection of prostate specific antigen could be realized.