Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements

Abstract

The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP) sensor with magnetic molecularly imprinted polymeric microspheres (Fe3O4@mSiO2@MIPs) as recognition elements. Using Fe3O4 as supporting core, mesoporous SiO2 as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe3O4@mSiO2@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe3O4@mSiO2@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe3O4@mSiO2@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles). The adsorption process of cartap on Fe3O4@mSiO2@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1–5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe3O4@mSiO2@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.

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

“…The MMIPs were synthesized by the following procedure. The magnetic Fe 3 O 4 particles, Fe 3 O 4 @mSiO 2 particles, and vinyl-modified Fe 3 O 4 @mSiO 2 particles were prepared in turn according to our previously published method [27,28,29], as follows. Firstly, FeCl 3 ·6H 2 O (1.35 g), polyethylene glycol (1.00 g) and sodium acetate (3.60 g) were dissolved in 40 mL of ethylene glycol and ultrasonicated for 30 min to form yellow solution, which was then transferred into a 100 mL dry polytetrafluoroethylene lined autoclave and heated at 200 °C for 8 h. After cooling down, the mixture was washed 3 times by triple distilled water and ethanol, respectively, and then dried in vacuum at 50 °C for 8 h to obtain black Fe 3 O 4 particles.…”

MIPs for commercial application in low-cost sensors and assays – An overview of the current status quo

“…Wu et al reported on the use of NPs with MIPs for the colorimetric detection of residues of the insecticide Cartap in tea [ 224 ]. Cartap was extracted from spiked and non-spiked samples of tea by means of magnetic molecular imprinted microspheres (Fe 3 O 4 @mSiO 2 @MIPs) that utilized methacrylic acid as a functional monomer.…”

“…Illumination of the filtrate with a simple UV-lamp visually confirms the presence or absence of the target. Adapted with permission from [ 224 ]. Copyright Elsevier 2019.…”

Molecularly Imprinted Materials for Selective Biological Recognition

“…In addition, the molecularly imprinted materials with magnetic components have attracted great attention due to their unique magnetic responsivity, low toxicity, and modifiable surface . Among these nanocomposites, magnetic core‐shell materials together with mesoporous nanostructures are of particular interest since they exhibit high surface area and porosities, excellent chemical and thermal stability . As shown in Figure B, Chen et al prepared a NIR‐light responsive magnetic lysozyme‐imprinted mesoporous microsphere with magnetic components, showing a high saturation adsorption capacity of 700 mg g −1 within 30 min for lysozymes because of the high surface area of 570 m 2 g −1 and the mesopore size of 12 nm.…”