Table 2.

Nanomaterial-based colorimetric (absorbance) sensors for AD biomarkers.

Nanomaterials	Biomarkers	Recognition element	Limit of detection	Sample	References
AuNPs	Aβ40	–	0.23 nM	Human serum	[99]
ZnO–Co3O4 nanocages	Aβ40	–	3.5 nM	Rat CSF	[102]
Metal ion conjugated MnO2 nanosheet	Aβ species	–	0.44 pM	Human blood	[104]
AuNPs	AβO	Aptamer	0.56 nM	aCSF	[107]
pA-pT-apt@AuNPs	AβO	Aptamer	3.03 nM	aCSF	[108]
AgNPs, AuNPs	Aβ40, Aβ42	–	–	Human plasma	[109]
Gelsolin modified AgNTs and AgNRs	Aβ40, Aβ42	–	–	Rat CSF and brain tissue	[111]

Abbreviations: aCSF: artificial cerebrospinal fluid, AgNPs: silver nanoparticles, AgNRs: silver nanorods, AgNTs: silver nanotriangles, AuNPs: gold nanoparticles, pA-pT-apt@AuNPs: aptamer-polythymine-polyadenine-gold nanoparticles, PBAS: polyvalent biotinylated aptamer scaffold.