Nanobiosensor based on gold nanoparticle and horse-pAb for the fast detection of SARS-CoV-2 spike protein

Since the emergence of COVID-19 pandemic there were near 22 million cases in Brazil, causing at least 594 thousand deaths.1 Despite the impressive development of diagnostic tests, there is still a lack of rapid antigen tests.2 We used previously purified horse polyclonal antibodies anti-S (a,b) covalently bonded to spherical gold nanoparticles (c,d,e), to prepare a nanobiosensor IgG@AuNP (c). This bioconjugate was employed in the identification of SARS-CoV-2 spike protein by monitoring the increment in the hydrodynamic diameter (ΔHD) determined by Dynamic Light Scattering (f) in an immunoassay. The present method is sensible, fast, inexpensive, and can potentially be applied to detect the virus in patients suspected of SARS-CoV-2 infection.