Table 2.

Developed biosensors for the detection of SARS-CoV-2.

Target	Biosensors	Principle	LOD/Detection Time/Cutoff Value/Sensitivity, Specificity	Drawbacks/Targets	References
Genome Based Detection	Label-free electrochemical biosensor	DNA hybridization of electrodeposited AuNPs immobilized with single-stranded nucleotide	-	RNA extraction Sensitive sample handling	[130]
	Plasmonic biosensors (optical-LSPR)	Dual-functional plasmonic biosensor combining the plasmonic photothermal (PPT) effect and localized surface plasmon resonance (LSPR) sensing transduction	0.22 pmol/L, 3 min	From multigene mixture	[131]
	Naked-eye colorimetric	Thiol-modified antisense oligonucleotide is used to cap AuNPs, which change color upon finding the target N-gene	0.18 ng/μL, 10 min	N-gene	[132]
Viral Particle Based Detection	Cell-based biosensor	Membrane-engineered mammalian cell containing antibody to bind with S-antigen	1 fg/mL, 3 min	Not applicable for the detection of variants.	[133]
	Nanoplasmonic sensors	Optical measurement of the SARS-CoV-2 particle	370 vp/mL, 15 min	Restricted for the S-antigen	[134]
	Field effect-based transistor	Graphene-coated sheets with SARS-CoV-2 antibody	2.42 × 102 copies/mL (in clinical samples)	s-antigen	[135]
	G-druplex-based biosensors			Whole genome	[136]
	Molecularly imprinted polymers	Monoclonal-type, synthetic antibodies of SARS-CoV-2	-	Only applied to the S-antigen	[137]
	eCovSens	Potentiostat-based sensor fluorine doped tin oxide + AuNPs immobilized with monoclonal antibody	90 fmol/L, 10–30 s	S-antigen	[138]
	Electrochemical Biosensor	Functionalized TiO2 nanotube-based electrochemical	0.7 nmol/L, 30 s	S-glycoprotein	[139]
	Lateral flow immunoassay	ACE2 enzyme binding captured antibody	1.86 × 105 copies/mL	Spike antigen	[140]
Antibody Based Detection	Lateral flow immunoassay	Lanthanide-doped Nanoparticles	0.06666, 10 min	Anti-SARS-CoV-2-IgG	[141]
		Immunochromatographic	15 min, 85.2% and 100%	IgG-IgM combined	[142]
		Immobilization on AuNPs	15 min, 88.66% and 90.63%	IgG-IgM combined	[40]
	Plasmon-enhanced biosensor	Grating Coupled Fluorescent Plasmonic (GC-FP) based on ELISA from dried blood spot samples	30 min 100% and 100%	Multiplexed (IgG, IgM, IgA)	[143]
	Opto-microfluidic	A microfluidic device fabricated by the electrodeposition of Au-nanospikes linked with the optic probe to detect the target by using localized surface plasmon resonance	0.5 pmol/L, 30 min	Antibodies against the spike protein	[144]