Synthesis of water-soluble, ultrabright Cu nanoclusters with core-shell structure via facile reduction approach for determination of 4-nitrophenol.

In this work, we reported a facile reduction approach for fabrication of water-soluble and ultrabright Cu nanoclusters with core-shell structure. A certain amount of reducing agent as NaBHwas introduced into the polyethyleneimine-stabilized Cu nanoclusters (CuNCs@PEI) system, which exhibited 4-fold fluorescence enhancement along with a blue shift of the emission peak. The variations of morphology, valence states and functional groups demonstrated that a Cu shell was formed surround CuNCs (defined as CuNCs-Cu@PEI), attributable to metal complex (PEI-Cuand PEI-Cu) reduction.