One-step eco-friendly approach for the fabrication of synergistically engineered fluorescent copper nanoclusters: sensing of Hg2+ ion and cellular uptake and bioimaging properties

Abstract

Herein, a single-step eco-friendly synthetic method was established for the fabrication of synergistically engineered fluorescent copper nanoclusters (Cu NCs) using curcuma root (Curcuma longa L.) extract (curcuminoids) as a template. These Cu NCs are water-soluble and emitted bright blue fluorescence under UV light illumination at 365 nm. The synergistically engineered Cu NCs exhibited an emission peak at 440 nm with quantum yield of 7.2%. Due to their optical properties, a new fluorescent analytical strategy has been developed for the sensing of Hg²⁺ ions and used to evaluate cellular uptake and bioimaging properties on cancer cells (RIN-5F and MDAMB231) and fungal cells (Penicillium citrinum). It was interestingly observed that Hg²⁺ ion effectively quenched the emission peak of Cu NCs at 440 nm, which indicates that Cu NCs act as a fluorescent sensor. Taking advantage of this, a novel fluorescent Hg²⁺ sensor has been established, which showed a linear range of 0.0005–25 μM with a detection limit of 0.12 nM at room temperature. Furthermore, Cu NCs exhibited good selectivity for Hg²⁺ against other inorganic species, and the potentiality of the method was demonstrated by detecting Hg²⁺ ions in water samples. Furthermore, Cu NCs act as probes for imaging of two cancer cells (RIN-5F and MDAMB231) and fungal cells (Penicillium citrinum), and the cell viability results reveals their nontoxic nature.