Polyethylenimine-protected green-emission copper nanoclusters as highly effective fluorescent and colorimetric nanoprobe for selective cobalt ions and temperature sensing.

Excessive uptake of Co is harmful to one's physical health and should not be ignored. Herein, a polyethylenimine (PEI) protected hydrophilic copper nanoclusters (PEI-CuNCs) with strong green fluorescence emission around 510 nm was apace synthesized employing a one-pot method without hyperthermia. Interestingly, the as-prepared water-soluble PEI-CuNCs can be specifically quenched by Co at pH 6.