Table 1.

Comparison of miR-21 detection with the reported methods.

Analytical Methods	Detection Limit	Linear Range	Ref.
Quartz crystal microbalance	3.6 pM	2.5 pM to 2.5 μM	[28]
Quartz crystal microbalance	0.87 pM	1.0 pM to 1.0 mM	[29]
Colorimetric	1 pM	1 pM to 1 nM	[30]
Electrochemistry	2.3 fM	10 to 70 fM	[31]
Electrochemistry	26 fM	100 fM to 100 nM	[32]
Electrochemistry	0.01 fM	0.01 fM to 1 μM	[33]
Electrochemistry	0.713 fM	20 fM to 600 pM	[34]
Fluorescence	200 pM	200 pM to 20 nM	[35]
Fluorescence	0.02 nM	0.02 to 5 nM	[36]
Fluorescence	0.89 fM	10 to 1 × 105 fM	This method