The inhibitory effect of captopril molecules on the nanozymatic activity of peroxidaselike nitrogen-doped carbon dots was evaluated by calculating their nanozymatic activity in the presence and absence of captopril. The UV-visible spectra of the oxidation product of TMB in the presence and the absence of different concentrations of captopril as an inhibitor are shown in Figure , revealing that the absorbance at 662 nm was significantly reduced by increasing the inhibitor concentration, showing the inhibitory effect of captopril molecules on the CDs-mediated oxidation of TMB. However, to provide a better view of the inhibitory effect of captopril on the nanozymes activity, the residual activity of nanozymes was calculated as a reliable index (Figure ). The results reveal that the relative activity of nanozymes was inhibited by increasing the inhibitor concentration and finally reached 23% of its initial activity, revealing a strong inhibitory effect of captopril on the nanozymatic behavior of peroxidase-like nitrogendoped carbon dots.