Table 2.

Sensing methods based on etching.

Ways Based on Etching	Type of Au NPs	Targets	Color Change	The Limit of Detection	Reference
direct etching of the target	Au NPLs	Chloramphenicol	from blue to red	10 μM & 1 μM	[78]
direct etching of the target	Au NRs	Helicobacter pylori	from blue to purple to red	40–2040 aM & 31.8 aM	[116]
reaction formation complex-induced etching	Au NSs	Pb2+	from blue-green to blue, to purple to red, and finally to colorless.	1.5 pM	[117]
reaction formation complex-induced etching	Au NBPs	I−	from blue-green to red	4 μM & 0.2 μM	[118]
oxidant-mediated etching	Au NBPs	Glucose	from light brown to blue to pink	0.02 μM	[77]
oxidant-mediated etching	Au NRs	Cu2+	rainbow colors	0.034 μM	[75]
inhibitor-mediated etching	Au NRs	ALP	from light brown to green to blue to pink	4.6 UL−1	[119]
inhibitor-mediated etching	Au NRs	UA	from light brown to blue to pink	0.76 μM	[7]