Fabrication Of Anti-interference Photoelectrochemical Sensor And Its Application In Biological Matrix

As a newly developed chemical analytical method,photoelectrochemical sensor is developed on the combination of photoelectrochemical process and specific biorecognition,and the principle of detection was that the electrical signal change could be produced by the biometric recognition between recognition elements and their corresponding target analytes.In the photoelectrochemical detection process,light is used to excite photoelectrochemically active species on the electrode,and current is used as the detection signal.Benefiting from the effective separation of the excitation light source and detection signal,photoelectrochemical sensor has many advantages,shch as high sensitivity,low background signal,simple device and so on.The adsorption of nonspecific matter such as proteins,lipids,cells and microorganisms could interfere with biosensor signals and consequently disrupt the output signals that are referred as biofouling.However,in many clinical and biological applications,they must be used in a complex biological matrix,which makes the assay with these devices complicated owing to severe biofouling.A promising way to prevent the nonspecific adsorption is surface functionalization with antifoulingmaterials.Inthephotoelectrochemicaldetectionprocess,the oxidation-reduction can take place in the photoanode.The biological medium contains rich reducing substances,which is adsorbed on the surface of the photoanode,thus may lead to photoelectrochemical?PEC?biosensor suffer severe interference from readily oxidizable species such as uric acid,ascorbic and carbohydrates.Therefore,it is very necessary to find effective ways to conquer these difficulties.This article aims at this question,from the new strategy for sensor and antifouling interfaces construction's angle,proposes the countermeasure.On the one hand,we herein present a general and efficient strategy for self-powered cathodic PEC immunoassay with evident photocurrent response by separating photoanode with capture probe to solve interference from reducing substances.For another,we introduction of functional materials to form low fouling interfaces to overcome severe biofouling.The main contents were summarized as below:?1?A general and efficient strategy for self-powered cathodic PEC immunoassay with evident photocurrent response by separating photoanode with capture probe was presented.In this chapter,the antigen?Ag?of human interleukin-6?IL-6?was selected as an example of target model.The TiO₂ nanotube arrays?TiO₂-NTAs?electrode was first modified with graphitic carbon nitride?g-C₃N₄?and thenpoly?3,4-ethylenedioxythiophenes??PEDOT?,producingTiO₂-NTAs/g-C₃N₄/PEDOT sensitized structure as photoanode.The indium-tin oxide?ITO?was deposited with reduced graphene oxide?RGO?to form ITO/RGO electrode,which served as the substrate of the cathodic sensing electrode to immobilize capture probe of IL-6 antibodies.This inspired design of the cathodic PEC immunoassay separating photoanode with capture probe owns two main unique advantages.First of all,the utilization of photoanode instead of photocathode can evidently enhance the photocurrent response without applied potential,resulting in good sensitivity.Second,this cathodic assay not only inherits anti-interference to reductive species of the traditional cathodic PEC assay,but also has anti-interference to exciting light because of no irradiation on cathode.Moreover,the proposed design idea opens up a new horizon to explore other types of self-powered cathodic PEC bioassays with both high sensitivity and anti-interference.?2?A robust PEC immunosensor with enhanced sensitivity and specificity based on evident photocurrent output of the photoanode and significant signal amplification of the biocathode was developed.Prostate specific antigen?PSA,Ag?was used as a target model to exhibit analytical performances of the designed PEC immunosensor.Two kinds of CuInS₂ quantum dots?CIS QDs?with different composition were modified on the TiO₂ nanotubes?TiO₂-NTAs?electrode to fabricate the photoanode.Due to the co-sensitization effect of the CIS QDs on TiO₂-NTs,an evident photocurrent output was generated at the photoanode.For the biocathode,Au nanoparticles?AuNPs?and polydopamine?PDA?were modified in order on indium-tin oxide?ITO?electrode to immobilize capture PSA antibody?Ab₁?.Carboxyl-modified polystyrene?PS?nanospheres were coated with secondary antibodies?Ab₂?to form PS@Ab₂ conjugates,which were used as signal amplifiers via the specific immunoreaction between Ag and Ab₂.Based on joint action of evident photocurrent output of the photoanode and significant signal amplification of the biocathode,the designed PEC immunosensor exhibited an ultralow detection limit of3.4 fg/mL for target PSA detection.Meanwhile,it also showed an enhanced specificity owing to the separation of the photoanode and the biocathode.?3?A novel biomaterial,polyglycerol grafted conducting polymer PEDOT was electrochemically synthesized.The PEDOT functionalized with hyperbranched polyglycerol?PEDOT-HPG?was simply prepared through the electrochemical polymerization of corresponding monomers,which was synthesized by grafting glycidol into?2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl?methanol?EDOT-MeOH?.The antifouling properties of PEDOT-HPG surfaces were evaluated in terms of protein adsorption and the attachment of mammalian cells,including human cervical carcinoma cells?HeLa?and michigan cancer foundation-7?MCF-7?.Through the conjugation of alpha-fetoprotein?AFP?antibodies to the PEDOT-HPG surfaces,sensitive immunosensors for AFP were fabricated,with the limit of detection at the level of 0.035 pg/mL.The prepared AFP biosensors exhibited excellent antifouling performance even in complex media and showed promising feasibility for the quantitative analysis of AFP in real samples.The PEDOT derivative with hyperbranched polyglycerol groups was effective to reduce biofouling and facile for surface functionalization.It is expected that this novel antifouling and conducting material may find broad applications in the development of photoelectrochemical sensors and biosensors capable of assaying targets in complex biological media.?4?A high-performance PEC cytosensor with pleased sensitivity and selectivity was developed based on a novel bifunctional PEDOT-HPG/SnS/ZnO-NTs photoelectrode.In this chapter,HeLa cell was chosen as a model cell for detection.ZnO nanotubes?ZnO-NTs?was first produced on the indium–tin oxide?ITO?glass by electrochemical deposition and chemical etching procedures.After SnS layer was deposited on the surface of the ZnO-NTs via solvothermal synthesis,hyperbranched polyglycerol?HPG?functionalized PEDOT was then further modified by polyreaction of its monomer to form the PEDOT-HPG/SnS/ZnO-NTs photoelectrode,which was served as the PEC matrix to modify the AS1411 aptamer.Due to evident photocurrent response and good antifouling capability of the fabricated bifunctional photoelectrode,the developed cytosensor exhibited high sensitivity and good selectivity toward target cell detection.