Vinyl Phosphate-Functionalized, Magnetic, Molecularly-Imprinted Polymeric Microspheres’ Enrichment and Carbon Dots’ Fluorescence-Detection of Organophosphorus Pesticide Residues

Abstract

The rapid detection of organophosphorus pesticide residues in food is crucial to food safety. One type of novel, magnetic, molecularly-imprinted polymeric microsphere (MMIP) was prepared with vinyl phosphate and 1-octadecene as a collection of dual functional monomers, which were screened by Gaussian09W molecular simulation. MMIPs were used to enrich organic phosphorus, which then detected by fluorescence quenching in vinyl phosphate-modified carbon dots (CDs@VPA) originated from anhydrous citric acid. MMIPs and CDs@VPA were characterized by TEM, particle size analysis, FT-IR, VSM, XPS, adsorption experiments, and fluorescence spectrophotometry in turn. Through the fitting data from experiment and Gaussian quantum chemical calculations, the molecular recognition properties and the mechanism of fluorescence detection between organophosphorus pesticides and CDs@VPA were also investigated. The results indicated that the MMIPs could specifically recognize and enrich triazophos with the saturated adsorption capacity 0.226 mmol g−1, the imprinting factor 4.59, and the limit of recognition as low as 0.0006 mmol L−1. Under optimal conditions, the CDs@VPA sensor has shown an extensive fluorescence property with a LOD of 0.0015 mmol L−1 and the linear range from 0.0035 mmol L−1 to 0.20 mmol L−1 (R2 = 0.9988) at 390 nm. The mechanism of fluorescence detection of organic phosphorus with CDs@VPA sensor might be attributable to hydrogen bonds formed between heteroatom O, N, S, or P, and the O−H group, which led to fluorescent quenching. Meanwhile, HN−C=O and Si−O groups in CDs@VPA system might contribute to cause excellent blue photoluminescence. The fluorescence sensor was thorough successfully employed to the detection of triazophos in cucumber samples, illustrating its tremendous value towards food sample analysis in complex matrix.

Green Preparation of Fluorescent Nitrogen-Doped Carbon Quantum Dots for Sensitive Detection of Oxytetracycline in Environmental Samples

“…Actually, fluorescence analysis has the advantages of high sensitivity, low cost, and simple operation, which has aroused great interest in the detection field [ 20 , 21 , 22 ]. Moreover, the fluorescence method can be applied to the detection of various organic pollutants and metal ions in the environment, including antibiotics (OTC [ 3 ], tetracycline [ 23 , 24 ], chlortetracycline [ 24 ], enrofloxacin [ 25 ]), metal ions (Au 3+ [ 26 ], Hg 2+ [ 27 , 28 ], Fe 3+ [ 24 , 29 , 30 ]), pesticides [ 31 , 32 ] 2,4,6 trinitrophenol [ 33 , 34 ], glutathione [ 35 , 36 ], and chitosan [ 37 ].…”

Smartphone-based molecularly imprinted sensors for rapid detection of thiamethoxam residues and applications

“…In recent years, rapid detection techniques for pesticide residues have been developed. Nowadays more researches are being conducted on enzyme inhibition techniques, enzyme immunoassay techniques, and biosensor techniques [ 29 , 30 ]. Electrochemical biosensing technology does not only have good accuracy and sensitivity, but also has the advantages of easy operation, low price and strong anti-interference ability.…”

“…In recent years, rapid detection techniques for pesticide residues have been developed. Nowadays more researches are being conducted on enzyme inhibition techniques, enzyme immunoassay techniques, and biosensor techniques [29,30]. Electrochemical biosensing technology…”

Fluorescent Carbon Quantum Dots—Synthesis, Functionalization and Sensing Application in Food Analysis

“…Wu et al have developed a vinyl phosphate (VPA)-functionalized, magnetic MIP (MMIP) microspheres for the enrichment of organophosphorus pesticide residues and further combined with CQDs for fluorescent detection [112] (Figure 6a). Dual functional monomers and mesoporous SiO 2 -modified Fe 3 O 4 magnetic particles (Fe 3 O 4 @mSiO 2 ) have prominent advantages in the formation of recognition cavities in MIPs, which further improve the sensing properties of the hybrid composites.…”

“…This type of composites has combined the advantages of a single material with different functions to form a synergistic enhancement effect and provides a very interesting strategy in the detection of small molecules. Wu et al have developed a vinyl phosphate (VPA)-functionalized, magnetic MIP (MMIP) microspheres for the enrichment of organophosphorus pesticide residues and further combined with CQDs for fluorescent detection [112] (Figure 6a). Dual functional monomers and mesoporous SiO2-modified Fe3O4 magnetic particles (Fe3O4@mSiO2) have prominent advantages in the formation of recognition cavities in MIPs, which further improve the sensing properties of the hybrid composites.…”