Talanta | 2021
Synthesis of highly fluorescent carbon dots as a dual-excitation rationmetric fluorescent probe for the fast detection of chlorogenic acid.
Abstract
Nitrogen and sulfur co-doped carbon dots (abbreviated as N,S-CDs) were obtained by two-step hydrothermal reactions using citric acid/sulfamic acid as precursors, polyethyleneimine (PEI) as passivation agent. It was found that the PEI modified CDs with a fluorescence quantum yield of up to 29.1%, showed an obviously enhanced photoluminescence (PL) compared to the initial CDs. Interestingly, when monitored at the fluorescence emission wavelength of 460\xa0nm, the dispersed N,S-CDs solution exhibits only one excitation band peaked at 355\xa0nm, while one aggregated N,S-CDs solution with good water solubility and excellent fluorescence stability possesses two well-separated excitation bands centered at 310 nm/397\xa0nm. When chlorogenic acid (CGA) was added to this aggregated N,S-CDs solution, the excitation peak at 310\xa0nm was obviously reduced due to the inner filter effect (IFE), whereas another peak at 397\xa0nm almost remained constant. Based on the above phenomenon, a dual-excitation ratiometric fluorescent probe for CGA assay was constructed. Under the optimized conditions, the logarithm of the fluorescence intensity ratios (F397/F310) exhibited a good linear correlation with the CGA concentration over a range from 0.33 to 29.70\xa0μg/mL with a detection limit of 0.12\xa0μg/mL. Moreover, the proposed sensing system was applied to determine CGA content in real samples with satisfactory results. The proposed sensing platform provides a new method for the detection of CGA.