Amino-functional Carbon Quantum Dots as a Rational Nanosensor for Cu2+

Abstract Intracellular copper (Cu2+) plays a crucial role in regulation of physiological and biological processes. Nevertheless, excessive copper from bioaccumulation may cause potential risk to human body. Hence, effective and sensitive identification system is essential to avoid excessive intake of copper. A novel highly sensitive fluorescent probe has been designed for detecting copper ion. Carbon dots was synthesized by citric acid and poly(amido amine) dendrimers (2G-PAMAM) as carbon and nitrogen source, respectively. Amino-functionalized carbon dots (NH2-CDs) was obtained by further modification by methyl acrylate and ethylenediamine reaction, which illustrated high quantum yield of 20% and small particle size of 25 nm. The functionalized NH2-CDs offered a rapid, sensitive and selective recognition of Cu2+ with a detection limit of 5 nM and a dynamic linear range from 0.005∼600 μM. As for practical application, the nanosensor illustrated good cell permeability and low cytotoxicity, and thus successfully applied for fluorescence imaging and biosensing of trace Cu2+ in MCF-7 and HepG-2 cells, which suggested the potential biological application in disease diagnosis.