Carbon dots electrochemically prepared from dopamine and epigallocatechin gallate for hypochlorite detection with high selectivity via a dynamic quenching mechanism

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 301; p. 122947
• Main Authors: Long, Tiantian, Hu, Zhongyang, Gao, Ziyun, Luo, Hongmei, Li, Hongchen, Chen, Yi, Liu, Lei, Xu, Dong
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.11.2023
• Subjects: Carbon - chemistry; Carbon dots; Dopamine; Dynamic quenching; Electrochemical method; Fluorescence; Fluorescent Dyes - chemistry; Hydrogen Peroxide; Hypochlorite; Hypochlorous Acid; Quantum Dots - chemistry; Spectroscopy, Fourier Transform Infrared; Water; Fluorescence; Carbon dots; Dynamic quenching; Electrochemical method; Hypochlorite
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2023.122947

[Display omitted] •A fluorometric assay for hypochlorite by using carbon dot (CD) was proposed.•Hypochlorite can quench the fluorescence of CDs via a dynamic process.•CDs were prepared by electrolysis of dopamine and epigallocatechin gallate under 10 V.•Our assay showed great selectivity over other oxidizing agents such as H2O2.•The assay was validated in water samples, with good recoveries. Monitoring hypochlorite levels in water is of great importance because of its high toxicity and wide applications as water disinfectants. In this manuscript, carbon dot (CD) was electrochemically prepared by using dopamine and epigallocatechin gallate (molar ratio 1:1) as the carbon source for efficient hypochlorite determination. By electrolyzing the solution at 10 V for 12 min with PBS as an electrolyte, dopamine would react with epigallocatechin at the anode, and through polymerization, dehydration, and carbonization, strong blue-fluorescent CDs were obtained. CDs were characterized by UV–Vis spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy, FT-IR, etc. These CDs have an excitation wavelength at 372 nm and an emission wavelength at 462 nm, owing an average particle size of 5.5 nm. The presence of hypochlorites can quench the fluorescence of CDs, and its reduction in intensity is linear with hypochlorite concentration over the range of 0.5–50 μM, ΔF/F0 = 0.0056 + 0.0194CClO−, R2=0.997. The detection limit achieved 0.23 μM (S/N = 3). The mechanism for fluorescence quenching is via a dynamic process. Different from many other fluorescence methods based on the strong oxidizing ability of hypochlorites, our method shows strong selectivity toward hypochlorites over other oxidizing agents such as H2O2. The assay was validated by the detection of hypochlorites in water samples, with recoveries between 98.2% and 104.3%.