Colorimetric detection of Cu2+ based on the inhibition strategy for etching reaction of AgNCs

In this study, an efficient and simple colorimetric method for sensing of Cu2+ was established using inhibition effect of Cu2+ to the etching reaction of silver nanocubes (AgNCs) induced by H2O2. The etching reaction of AgNCs changes its morphology and absorbance with the visual appearance from yellow to colorless. On the contrary, the presence of Cu2+ can significantly inhibit the etching progress. Thus Cu2+ induces the obvious absorbance enhancement compared with AgNCs/H2O2 system. This design realizes colorimetric detection of Cu2+ based on the inhibition effect of etching reaction using AgNCs nanoprobe. The colorimetric response of AgNCs nanoprobe in ΔAbs417.5 shows the linearity with the increasing concentrations of Cu2+ from 0.01 to 40 μM with good selectivity. The concentration limit of Cu2+ efficaciously discriminated by the naked eye is as low as 0.01 μM. Furthermore, the Euclidean distance (ED) of the difference map in RGB change before and after response with Cu2+ is applied for further visualization recognition of Cu2+. All the above results indicate the outstanding practicability and accuracy of the proposed assay for Cu2+ sensing.