Application Of Photoelectrochemical Flow Injection Immunoassay In Detecting Novel Coronavirus

The coronavirus outbreak has posed a major challenge to the detection and diagnosis of the disease,and rapid and accurate detection of the novel coronavirus is of great importance to the prevention and control of the epidemic.Photoelectrochemical（PEC）technology is widely used in food safety,medical research,environmental protection and other fields due to its excellent sensitivity,easy operation and low instrument price.Among them,the PEC biosensor prepared by using photosensitive materials with good biocompatibility and excellent chemical stability can significantly reduce background noise,thus greatly improving the detection accuracy.However,when the traditional PEC sensor is used for the capture and regeneration of analytes,it can only be regenerated five times due to the degeneration of antibodies and/or pollution caused by environmental surface regeneration.The flow-injection-photochemical analysis system（FIA-PEC）can realize 10 consecutive analyte detection and sensor surface regeneration due to its advantages such as good airtight,small operation influence and strong chip anti-fouling ability.Therefore,our system is based on a self-designed and 3D printed thin-layer flow cell with small volume and light.Indium tin oxide（ITO）covered with glass auxiliary electrode allows visible light to shine on the photoanode.Combined with the flow injection system,it can be used for accurate and real-time photochemical immunoassay of S protein antibodies and N protein antibodies.In this paper,TiO₂ nanotube array（TiO₂ NTA）photosensitive material modified by gold nanoparticles（Au NPs）with good chemical stability was used to construct FIA-PEC immunosensor,and polyethylene glycol（PEG）film was used to modify the surface of the sensor to improve the stability of the sensor surface.At the same time,a double-channel thin-layer flow cell was innovatively used to fix S1 protein and N protein,markers of novel coronavirus,respectively,on the surface of the double electrodes.Only a tiny sample（200μL）could simultaneously detect the specific antibodies of the two proteins,improving the accuracy of detection.The bioimmunosensor can regenerate the surface of the sensor for 10consecutive times and detect the analyte,and the detection limit is lower than the range of0.15-10 ng/m L achieved by enzyme-linked immunosorbent assay（ELISA）.In addition,PEG molecules with hydrogel properties modified with specific groups can prevent non-specific adsorption of substances in complex biological substrates to the sensor surface,which is not possible with unmodified semiconductor electrodes or with non-hydrogel-based chemical modifiers.The PEG chip’s excellent anti-fouling performance enabled us to validate the accuracy of our renewable sensor by comparing PEC and ELISA immunoassays in patient sera.Therefore,we adopted the FIA-PEC method to construct a TiO₂ NTA/Au NPs/PEG sensor chip to achieve a more simple and fast analysis and detection of COVID-19 markers.