Fig. 2.

Biosensors for SARS-CoV-2 virus detection. a CRISPR based nucleic acid (RNA) detection. RNA transcripts containing the target sequence (green) are recognized by RNA guided Cas endonuclease and CRISPR-RNA (Cr-RNA) carrying the complementary sequence. The formation of the Cas-crRNA-RNA-transcript tertiary complex switches on the ‘collateral cleavage’ activity, thereby dramatically applying the fluorescent signal in the presence of the target RNA. Q quencher, F fluorophore (Zuo et al. 2017; Broughton et al. 2020). b Schematic diagram of COVID-19 FET based biosensor operation. SARS-CoV-2 spike antibody is conjugated onto the graphene sheet via 1-pyrenebutyric acid N-hydroxy-succinimide ester, which is an interfacing molecule, as a probe linker (Seo et al. 2020). c The FTO electrode consist sensing area made up of AuNPs conjugated with nCOVID-19 Ab either by physisorption or electrostatic bonding (Mahari et al. 2020). d Surface Plasmon Resonance (SPR) based biosensor for COVID-19 detection. Activation of the AffiCoat surface, the nucleo-capsid protein of SARS-CoV-2 are bound to the SPR chip, and remaining activated sites were passivated with ethanolamine. e Schematic diagram of the 2D gold Nanoislands (AuNIs) functionalized with complementary thiol-cDNA ligands