Fluorescent sensor for indirect measurement of methyl parathion based on alkaline-induced hydrolysis using N-doped carbon dots

• Published in: Talanta (Oxford) 2019-01, Vol.192, p.368-373
• Main Authors: Lan, Shiyu, Wang, Xianfeng, Liu, Qingyan, Bao, Jing, Yang, Mei, Fa, Huanbao, Hou, Changjun, Huo, Danqun
• Format: Article
• Language: English
• Subjects: Carbon dots; Fluorescent biosensor; Inner filter effect; Methyl parathion
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2018.08.083

High-performance measurement of methyl parathion (MP) is of great importance in both agricultural and environmental surveillance. Herein, we presented a facile fluorescent biosensor to indirectly measure MP using N-doped carbon dots (N-CDS) based on the inner filter effect (IFE). Methyl parathion was employed as the substrate of alkaline-catalytic hydrolysis, and p-nitrophenol (p-NP) was obtained by rapid the hydrolysis reaction under strong alkaline conditions without enzymes. Interestingly, the absorption band of p-NP appeared at 403 nm, which presented an overlapping spectrum with the excitation of N-CDs (410 nm). Due to its strong molar absorptivity, p-NP played the part of a powerful absorber in IFE to influence the excitation of fluorophore (N-CDs). Through the competitive absorption, the fluorescence intensity of N-CDs decreased extremely. With optimum conditions selected, the fluorescent sensor presented a concentration-dependent fluorescent response (ΔF) to MP ranging from 0.075 to 15 ppm (R2 =0.9956). The limit of detection was calculated to be 1.87 ppb (S/N = 3) with good selectivity. Successful measurement of MP in spiked river water and apple samples demonstrated that as-proposed optical sensor provided an alternative strategy for real applications in environmental and food safety control. [Display omitted] •N-doped carbon dots were innovatively introduced as fluorescent signal readout for measurement of methyl parathion.•This strategy realized the quantitative analysis for MP via enzyme-free process rather than enzymatic hydrolysis of MP.•This work could serve as a good model for the design of new fluorescence biosensors based on inner filter effect.•MP was successfully measured in river water and apple sample with high selectivity and satisfactory detection limit.