A Practical Spectroscopic Protocol Based on Sialic Acid‐S‐Protein Interaction for SARS‐CoV‐2 Detection

This work aims to investigate the possible role of sialic acids as host cell receptors for SARS‐CoV‐2 infection and hence to develop a practical spectroscopic protocol that relies on the interaction between fetuin and spike protein (S‐protein) for SARS‐CoV‐2 detection. For that purpose, firstly, synthesized gold nanoparticles (AuNPs) were functionalized with fetuin. Then, fetuin functionalized AuNPs were incubated with S‐protein and the difference in absorbance value of AuNPs at 530 nm was measured spectroscopically. The interaction between fetuin and S‐protein was characterized by using fourier transform infrared spectroscopy and atomic force microscopy methods whereas sole AuNP structure was investigated by using transmission electron microscopy technique. The experimental parameters such as fetuin amount (0, 5, 10, and 20 µg/mL) and incubation duration (0, 10, 20, 30, and 40 min) were optimized and analytical characteristics of developed biosensors were investigated. The detection limit value was calculated as 2.40 ng/mL, the linear range of detection was between 4.98 and 95.2 ng/mL, and the relative standard deviation value was 0.72% for 9.95 ng/mL S‐protein. Finally, the developed biosensor was applied to real samples that were taken from SARS‐CoV‐2 non‐infected and infected individuals. The working principle of this study is based on AuNP interactions with fetuin for S‐protein detection. AuNP exhibits higher reactivity compared to other metals due to its elevated surface energy, which leads it to interact readily with biomolecules. In this study, fetuin is adsorbed onto AuNP surface and then, S‐protein interacts with this resulting structure.