A Ratiometric Fluorescence Probe of Dopamine-Functionalized Carbon Nanodots for Hypochlorite Detection

Abstract

A dopamine-functionalized carbon nanodot (C-dots) ratiometric fluorescence probe for hypochlorite (ClO−) detection is reported. Fluorescent C-dots with maximal emission at 420 nm are synthesized via the hydrothermal synthesis of 3-hydroxyphenylboric acid at 160 °C for 8 h. After modified with dopamine for 5 min, the obtained dopamine-functionalized C-dots exhibit two maximal fluorescence emissions at 420 nm and 460 nm. Fluorescent intensity at 460 nm gets quenched with the addition of ClO− and fluorescent intensity at 420 nm is almost unaffected. Therefore dopamine-functionalized C-dots can be used as ratiometric fluorescence probe for highly sensitive detection of ClO−. The ratio of fluorescent intensity at 460 nm and 420 nm (I460nm/I420nm) has a linear relationship with the concentration of ClO− from 2 μM to 60 μM and limit of detection (LOD) of 0.6 μM. It shows high selectivity for the detection of ClO− toward other anions (SO42−, Cl−, NO3−, S2−, CO32−), metal ions (Mg2+, Ba2+, Ag+, Fe3+, Ca2+, Na+, Cr6+, Cr3+, Hg+), or other substances such as H2O2, glutamate, cysteine, and citric acid. When it is utilized in ClO− detection in tap water, the average recoveries are from 95.7% to 103.2% with the relative standard deviations (RSDs) lower than 5%.