Table 2.

The detection limits of an electrochemical aptamer sensor for thrombin

	Detection limit	Characteristics	Reference
1	3 nM	Uses an MB-tagged "holding" DNA sequence	[31]
2	80 nM/3.5 nM	Peroxidase-labeled thrombin gives an 80 nM detection limit. Biotin-labeled aptamer with horse radish peroxidase labeled streptavidin gives a detection limit of 3.5 nM	[27]
3	1 μM	Sandwich assay using two aptamers with different binding sites. Secondary aptamer labeled with glucose dehydrogenase	[28]
4	10 nM	Same as for 3, but pyrroquinoline quinine glucose dehydrogenase is used for labeling	[29]
5	6.4 nM	MB-tagged thrombin aptamer (signal-off sensor)	[30]
6	0.1–0.15 nM	Thrombin aptamer with ferrocene moiety (square-wave voltametry or chronopotetiometry used for the measurement)	[32]
7	11 nM	MB-intercalated thrombin aptamer	[25]

MB methylene blue