2,4-Dichlorophenoxyacetic acid-imprinted

The scientists from Hong Kong reported83 on a sol-gel derived molecular imprinted polymers (MIPs) based luminescent sensing material that made use of a photoinduced electron transfer (PET) mechanism for a sensing of a non-fluorescent herbicide - 2,4-dichlorophenoxyacetic acid. A new organosilane, 3 - [N,V-bis(9-anthrylmethyl)amino]propyltriethoxysilane, was synthesized and use as the PET sensor monomer. The sensing MIPs material was fabricated by a conventional sol-gel process. 

Leung M., Chow C., Lam M., A sol-gel derived molecular imprinted luminescent PET sensing material for 2,4-dichlorophenoxyacetic acid, J. Mater. Chem. 2001 11 2985-2991. 

Surugiu et al. [67] have introduced an Enzyme Immuno-Like Assays (EzILA) for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The label was a 2,4-D conjugate with the tobacco peroxidase (TOP) enzyme, which allows for both colorimetric and chemiluminescent detection. In this case, the polymer imprinted with 2,4-D was synthesized in the form of microspheres. In contrast, despite its higher binding capacity for radiolabeled 2,4-D, a conventional MIP prepared by bulk polymerization showed only weak binding of the 2,4-D-TOP tracer. 

HAUPT K, dzgoev A and masbach K (1998), Assay system for the herbicide 2, 4-dichlorophenoxyacetic acid using a molecularly imprinted polymer as artificial recognition element , Anal Chem, 70, 628-631. 

Fig. 5.19. Molecular imprinting of 2,4-dichlorophenoxyacetic acid using 4-VPY as functional monomer and methanol as diluent as described by Haupt et al. [33].

An approach similar to the amperometric morphine sensor has very recently been described by Kroger et al. [81]. Particles of poly(EDMA-co-4-vinylpyridine) imprinted with 2,4-dichlorophenoxyacetic acid were trapped in agarose on a screen-printed carbon electrode. The sensor was equilibrated in a solution of the template analyte species with a fixed amount of the electroactive competitor homogentisic acid, then the free homogentisic acid was quantified by differential pulse voltammetry. This approach has the advantage of being applicable to non-redox-active species, provided a suitable redox-active competitive probe can be found. 

Applications. An example of practical approach based on polymer-imprinted materials is the development of biosensors for the detection of the herbicides atrazine [87] and 2,4-dichlorophenoxyacetic acid (2,4-D) [88]. The first one is based on conductimetric detection and it uses an atrazine selective polymeric matrix generated from triethylene glycol dimethacrylate... 

Fig. 3-8 Molecular imprinting of 2,4-dichlorophenoxyacetic acid (2,4-D) using 4-vinylpyridine as a functional monomer...

Moreover, a magnetic molecularly imprinted polymer of 4-divinylpyridine and EGDMA particles was synthesized by inverse suspension polymerization [119]. The reaction was carried out in silicon oil as a dispersion phase, and in the presence of 2,4-dichlorophenoxyacetic acid and MPTS. The advantages of the silicon oil as a continuous phase are a low polarity and immiscibility with the monomer mixture. The prepared particle average size is 20 pm and the magnetic content is very low, at around 1 wt%. 

Yongliang Liu, He Yonghuan, Jin Yulong, Huang Yanyan, Liu Guoquan, and Zhao Rui. Preparation of monodispersed macroporous core-shell molecularly imprinted particles and their application in the determination of 2,4-dichlorophenoxyacetic acid. J. Chromatogr. A. 1323 (2014) 11-17. 

Figure 7.10. Standard curves for 2,4-dichlorophenoxyacetic acid (2,4-D).Displacement of CMMC from the 2,4-D-imprinted MIP by 2,4-D (I), CPOAc ( ) and POAc (A) in a) 20 mM phosphate buffer, pFf 7, 0.1% Triton X-100 b) acetonitrile. Reprinted with permission from Haupt K, Mayes AG, Mosbach K. Herbicide assay using an imprinted polymer-based system analogous to competitive fluoroimmunoassays. Anal Chem 1998 70 3936-3939. 1998 American Chemical Society...

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