Photoelectrochemical biosensing platform for the SARS‐CoV‐2 spike and nucleocapsid proteins

The COVID‐19 pandemic is still a continuing worldwide challenge for public health systems. Early and ultrasensitive identification of the infection is essential for preventing the spread of COVID‐19 by pre‐symptomatic or asymptomatic individuals, particularly in the community and in‐home settings. This work presents a versatile photoelectrochemical (PEC) immunosensor for SARS‐CoV‐2 detection based on a composite material formed by bismuth vanadate (BiVO4) and strontium titanate (SrTiO3). The PEC platform was denoted as BiVO4/SrTiO3/FTO, and it can be tuned for the detection of either Spike (S) or Nucleocapsid (N) protein by simply altering the antibody immobilized on the platform's surface. Chemical, morphological, and electrochemical characterizations were performed by X‐Ray Diffraction, Scanning Electron microscopy, Energy‐dispersive X‐ray spectroscopy, Electrochemical Impedance Spectroscopy, and Amperometry. With a simple sensing architecture of the PEC platform, it was possible to achieve a linear response range of 0.1 pg mL−1 to 1000 ng mL−1 for S protein and 0.01 pg mL−1 to 1000 ng mL−1 for N protein. The PEC immunosensors presented recovery values for the two SARS‐CoV‐2 proteins in artificial saliva samples between 97 % and 107.20 % suggesting a good accuracy for the proposed immunosensors.