Avaliação de plataformas fotoeletroquímicas à base de titanato de estrôncio para detecção de antígenos SARS COV-2

Abstract

The COVID-19 pandemic, which began in 2019, continues to pose a persistent global challenge to public health systems. Early and highly sensitive detection of the infection plays a crucial role in preventing the spread of the virus through pre-symptomatic or asymptomatic individuals, especially in communities and home settings. This work describes the development of photoelectrochemical (PEC) immunosensor platforms based on SrTiO3 for the detection of SARS-CoV-2. These platforms are designed by modifying a glass slide coated with a fluorine doped tin dioxide (SnO2-F) film – FTO. The first platform consisted of strontium titanate nanoparticles (SrTiO3 or ST), sulfur-doped graphitic carbon nitride (g–C3N4–S or CNS), and palladium nanoparticles encapsulated in aluminum hydroxide (PdAlO(OH) or PdNPs). The second platform was based on a composite material composed of SrTiO3 and bismuth vanadate (BiVO4). The PEC platforms were designated as PdNPs/CNS/ST/FTO and BiVO4/SrTiO3/FTO, and in both photoelectrochemical systems, ascorbic acid (AA) was used as the electron donor molecule. The chemical, morphological, and electrochemical characterizations were performed using the following techniques: X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Transmission Electron Microscopy, Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Electrochemical Impedance Spectroscopy, and Amperometry. The FEQ responses of the platforms were optimized by evaluating the effects of the donor molecule, buffer nature, pH, antibody concentration, applied potential to the working electrode and interaction time between the antigen and the antibody. Thus, it was possible to monitor the decrease in photocurrent of the FEQ platforms containing the spike or nucleocapsid antigens of SARS-CoV-2. For the PdNPs/CNS/ST/FTO platform, an increase in the concentration of the SARS-CoV-2 Spike antigens from 1 fg mL⁻¹ to 1000 pg mL⁻¹ was observed. For the BiVO4/SrTiO3/FTO platform exhibited a linear response range from 0.1 pg mL⁻¹ to 1000 ng mL⁻¹ for the Spike protein and from 0.01 pg mL⁻¹ to 1000 ng mL⁻¹ for the Nucleocapsid protein. The proposed immunosensors were successfully applied to artificial saliva samples, showing recovery values ranging from 96.20% to 109.65% and 97% to 107.20%, respectively, as well as good selectivity, precision, and accuracy. These results indicate that the proposed platforms can be considered promising alternatives for the detection of SARS-CoV-2.