Ratiometric Fluorescent Sensor Based on Hydrogen-Bond Triggering the Internal Filter Effect for Enzyme-Free and Visual Monitoring Pesticide Residues

Abstract

Real-time/field sensing techniques to keep track of methyl parathion (MP) are crucial to human health. In this work, a ratiometric fluorescence probe was constructed by integrating green carbon dots and CdTe quantum dots (CdTe QDs) for highly selective quantitative detection of MP. Under alkaline conditions, MP can be rapidly hydrolyzed to produce pnitrophenol (p-NP); the instantaneous reaction that strengthens the hydrogen bond results in the internal filter effect between the carbon dots and p-NP, which quenches green fluorescence, thus leading to an obvious and immediate change from green to red. The probe displayed a sensitive limit of detection of 8.9 nM and exhibited a significant linear response to MP residue concentrations in the range of 0−100 M. In addition, we have created a brand-new smartphone-based intelligent detection tool by measuring the RGB value of the fluorescent probe solution and the matching paper-based sensor, and we are able to visually and quantitatively identify the levels of MP residues present in water, apples, and vegetables. This ratiometric fluorescence sensing method can realize rapid visual and quantitative detection of MP residues, which provides a more reliable guarantee promising strategy for constructing a risk detection technique for traces without enzymes.

Advances in Carbon Dot-Based Ratiometric Fluorescent Probes for Environmental Contaminant Detection: A Review

“…This method offers a rapid and convenient approach to creating ratiometric fluorescent probes for environmental contaminant detection. CDs are physically mixed with other reference luminescent materials, such as polymers, nanoparticles, or other fluorophores, to establish a dual-emission system [ 67 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 ] ( Figure 3 a).…”

“…The fluorescent ratiometric probe exhibits an impressively low detection limit of 4.6 nM. Qin et al [ 88 ] developed a ratiometric fluorescence probe that combines green CDs with CdTe QDs, enabling highly selective and quantitative detection of methyl parathion (MP) ( Figure 3 b,c). Under alkaline conditions, MP undergoes rapid hydrolysis, yielding p-nitrophenol (p-NP).…”

“…Pharmaceutical residues can disrupt ecosystems, contribute to antibiotic resistance, and lead to various health issues, including allergies and poisoning. Monitoring and controlling pharmaceutical residues are crucial to mitigate these risks [ 65 , 69 , 81 , 88 , 105 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 ] ( Figure 6 b). One fundamental mechanism in detecting pharmaceutical residues is related to electron transfer processes.…”

“… ( a ) Dual-colored CD ratiometric fluorescent test paper for the semiquantitative assay of Cu 2+ [ 92 ]; ( b ) integration of green CDs and CdTe quantum dots for highly selective quantitative detection of MP [ 88 ]; ( c ) sensing mechanism of internal filtration effect (IFE) of p-NP to green CDs (* represents the excited state) [ 88 ]. …”

Simple and sensitive fluorescence sensing of methyl parathion based on the inner filter effect of p‐nitrophenol on nitrogen‐doped titanium carbide quantum dots

“…Currently, some interesting fluorescence assays have been reported to detect MP [16,17]. For example, Huang et al [18] constructed a ratiometric fluorescence probe for the AChE activity evaluation and OPs detection via inner filter effect (IFE) of 2,3-diaminophenazine on nitrogen doped carbon dots.…”