Table 2.

Summary of colorimetric reporters and their performance.

Colorimetric Reporters	Mechanism	Color Change (Negative-Positive)	LoD (Copies a or CFU b per Reaction)	References
Phenol red	pH	Red-Yellow	50–1000 a	[83,89,164]
Phenolphthalein	pH	Pink-Colorless	1.225 b	[165]
Chemosensor-L	pH	Yellow-Colorless	0.5 b	[166,167]
MColorpHast	pH	Green/brown-Yellow	3.36 × 104 a	[168]
Crystal violet	DNA-binding	Colorless-Purple	4413 a	[169]
Methylene blue	DNA-binding	Colorless-Blue	25 b	[170]
Fuchsin	DNA-binding	Colorless-Purple	1–300 b	[171,172]
Gold nanoparticles	Aggregation	Colorless-Red	1.806 × 105–1.806 × 109 a	[173,175]
Silver nanoparticles	Aggregation	Colorless-Yellow	1.55 × 1010–2.30 × 1010 a	[176]
Polystyrene latex microspheres	Aggregation	Colorless-Red/ Colorless-Blue	1.806 × 1011 a	[177,178]
Hydroxynaphthol blue	Mg2+ depletion	Violet-Blue	2.07 × 104 a	[179]

LoD was converted to copies/reaction when possible. LoD values reported in terms of mass were converted to copies using the reported length of the target DNA or when a specific accession/sequence was not specified, the median genome length of the target organism on GenBank was utilized for estimating copy number. LoD values reported as CFU were not converted due to the lack of clear correlation between CFU and gDNA copies. ^a copies/reaction; ^b colony forming unit (CFU)/reaction.