Considering that the peak current suppression depended on the
conformation-changed FNP-TBA, the aptasensor could be employed
for the quantitative detection of TMB via DPV measurement. The
aptasensor displayed excellent DPV responses to TMB (Fig. 2D), where
the suppression percentage exhibited a linear response with TMB
concentration from 1 nM to 60 nM with a correlation coefficient of
0.995. When TMB concentration was higher than 75 nM, the signal
almost reached saturation, suggesting that most of FNP-TBA probes
have combined with TMB. The detection limit was calculated to be
0.1 nM (S/N= 3), which is lower than those of MB-tagged E-AB
sensors [7,23]. Noteworthily, since the detection linear range of TMB
produced in nanomolar concentrations, the FNP-TBA E-AB sensor
could be used in clinical analysis.