Facile and Green Synthesis of Bifunctional Carbon Dots for Detection of Cu2+ and ClO- in Aqueous Solution

Devising novel water-soluble carbon dots (CDs) with a facile and economical process is pivotal for the detection of ions in the environment. In this paper, novel nanoscale CDs (polyethyleneimine-2,4-dihydroxybenzoic acid (PEI-DA)) with water solubility and bifunctional detection were synthesized from hyperbranched polyethyleneimine (hPEI) and 2,4-dihydroxybenzoic acid (DA) via a hydrothermal reaction and further selfassembly. PEI-DA exhibited a good linear relationship with Cu2+ or ClO- in the range of 0-30 mu M, and its detection limit was determined to be 193 nM (Cu2+) or 478 nM (ClO-). Meanwhile, PEI-DA presented excellent hypotoxicity and biocompatibility in living cells (HeLa cells). On the basis of extraordinary fluorescence properties, PEI-DA-doped solid sensors (test strips and nanofibrous films) were successfully employed to monitor targets sensitively. More importantly, the fluorescence hydrogel was further constructed to rapidly respond to targets (Cu2+ and ClO-), and it could effectively remove Cu2+ in aqueous solution through adsorption ability. In summary, these simple sensing techniques could be implemented as effective tools to monitor Cu2+ and ClOin environmental and biological samples.

Automated summary

Novel water-soluble carbon dots (CDs) were successfully synthesized with the ability to detect copper ions and hypochlorite in the environment. These CDs showed low toxicity and biocompatibility in living cells, and were effectively used in solid sensors and hydrogels for sensitive monitoring of targets.