Figure 3 | Scientific Reports

Figure 3

From: Development of loop-mediated isothermal amplification (LAMP) assays using five primers reduces the false-positive rate in COVID-19 diagnosis

Figure 3

Testing the effect of adding 40 mM guanidine hydrochloride (GuHCl) in (a) colorimetric RT-LAMP reaction on positive clinical samples (P13, P14, J10, J49) and an inconclusive sample (J43). This addition improved the detection time in one sample (J49), where it started to change color 8 min earlier compared to reactions without GuHCl. The inconclusive sample J43, however, remained negative in both. The red dashed rectangle highlights the samples having an earlier color change to yellow with the GuHCl addition at the same reaction time. (b) Fluorometric RT-LAMP PC and NTC triplicate test with and without GuHCl. All PC triplicates with GuHCl amplified earlier than those without. There were no amplifications in NTC in both colorimetric and fluorometric tests, suggesting that GuHCl enhances the detection speed without causing misamplification in the NTC.

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