Colorimetric detection of Cu 2+ based on the inhibition strategy for etching reaction of AgNCs.

In this study, an efficient and simple colorimetric method for sensing of Cu ²⁺ was established using inhibition effect of Cu ²⁺ to the etching reaction of silver nanocubes (AgNCs) induced by H ₂ O ₂ . The etching reaction of AgNCs changes its morphology and absorbance with the visual appearance from yellow to colorless. On the contrary, the presence of Cu ²⁺ can significantly inhibit the etching progress. Thus Cu ²⁺ induces the obvious absorbance enhancement compared with AgNCs/H ₂ O ₂ system. This design realizes colorimetric detection of Cu ²⁺ based on the inhibition effect of etching reaction using AgNCs nanoprobe. The colorimetric response of AgNCs nanoprobe in ΔAbs _417.5 shows the linearity with the increasing concentrations of Cu ²⁺ from 0.01 to 40 μM with good selectivity. The concentration limit of Cu ²⁺ 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 Cu ²⁺ is applied for further visualization recognition of Cu ²⁺ . All the above results indicate the outstanding practicability and accuracy of the proposed assay for Cu ²⁺ sensing.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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