Update on the Development of Toehold Switch-Based Approach for Molecular Diagnostic Tests of COVID-19

Table 1

Characteristics of currently developed toehold switch-based diagnostics for COVID-19.

Methods (references)	Amplification step	Viral RNA sources	Detection time	Observation results	Limit of detection	Estimated price per reaction
PHAsed NASBA-translation optical method (PHANTOM) [40]	Yes, isothermal NASBA (nucleic acid sequence-based amplification)	Nasopharyngeal swab samples	60-100 minutes	Naked eye, camera, and microplate reader	100 copies of viral RNA per sample	N/A
[41]	Yes, isothermal NASBA (nucleic acid sequence-based amplification)	Nasopharyngeal swab samples	60-120 minutes	Naked eye, camera, and microplate reader	1800 copies of viral RNA per sample	<1.00 USD
[42]	Yes, reverse transcription loop-mediated amplification (RT-LAMP)	Saliva	70 minutes	Naked eye, camera, and microplate reader	120 copies of viral RNA per sample	N/A
[43]	No	Saliva	Up to 7-12 minutes	Naked eye in the darkroom, camera	10 nM RNA per sample	<0.50 USD