Table 1.

Summary of signal-enhancement based on nanomaterials and non-nanomaterials.

Signal enhancers	Signal/method	Sensitivity enhancement	Detection limit (M)	Reference
SnO2 nanorods	fluorescence	5-fold	1.0 × 10−12	43
nanoscale TiO2, SnO2, and Fe3O4 films	current		2.1, 5.4, and 4.6 × 10−8, respectively	44
walnut-like CdS NPs	current/cyclic and differential pulse voltammetry	ca. 3-fold	6.0 × 10−14	46
streptavidin-functionalized QDs	fluorescent/colorimetric measurement		< 1.0 × 10−9	62
single-QD	fluorescence/FRET	100-fold	4.8 × 10−15	63
CdSe/ZnS core-shell QDs	fluorescence/FRET		< 1.0 × 10−9	72
CdSe-ZnS QDs and magnetic beads	fluorescence/FRET	>100-fold	5.0 × 10−13	74
ZnCdSe alloy QDs	fluorescence/FRET	ca. 15-fold		75
AuNPs	frequency		1.0 × 10−14	81
AuNPs	photocurrent	ca. 2-fold		82
AuNPs	current/cyclic voltammetry		1.0 × 10−11	83
AgNPs	fluorescence	>10-fold		90
AgNPs	fluorescence	28-fold		91
AgNPs	current/anodic stripping voltammetry		0.03 ng/mL (IgG)	92
MWCNTs	current/cyclic voltammetry		3.81 × 10−11	98
MWCNTs/ZnO/chitosan composites	current/differential pulse voltammetry		2.8 × 10−12	99
Au/MWCNTs	current/differential pulse voltammetry		< 1.0 × 10−12	100
single electron transistor (non-nanomaterials)	current		2.5 × 10−11	103
cationic conjugated polymers and PicoGreen (non-nanomaterials)	fluorescence		1.0 × 10−10	106
enzyme	current	2-fold	1.0 × 10−9	108
enzyme	current		1.2 × 10−11	110