Facile synthesis of PEG-modified fluorescent carbon dots for highly sensitive detection of Ag

Silver-based compounds are widely used in modern society. However, excessive use and uncontrollable discharging of silver ions (Ag+) pose a potential threat to personal safety and the environment. In this work, PEGmodified fluorescent carbon dots (PEG-CDs) were synthesized through a facile solid-state reaction, exhibiting bright blue emission with a high photoluminescence quantum yield of 73.9%. The fluorescence of as-prepared PEG-CDs can be significantly quenched by the addition Ag+, showing high selectivity and sensitivity even without interference from high concentrations of other metal ions. The fluorescence intensity decreases linearly with Ag+ from 0 & mu;mol/L to 200 & mu;mol/L with a limit of detection of 0.114 nmol/L.