Cyclodextrin-Based Molecularly Imprinted Polymers for the Efficient Recognition of Pyrethroids in Aqueous Media

摘要

Recent years have witnessed growing applications of the molecular imprinting technique for the detection of pesticide residues in environmental and food samples. In this study, molecularly imprinted polymers (MIPs) for pyrethroids, a class of popular insecticides, were synthesized by the crosslinking of β-cyclodextrin (β-CD) with 1,6-hexamethylene diisocyanate (HMDI) or toluene- 2,4-diisocyanate (TDI) in dimethyl sulfoxide, with lambda-cyhalothrin (LCT) as a model template. Equilibrium batch-rebinding tests were operated in different aqueous solutions. The results indicate that MIP prepared with TDI (MIP-TDI) possessed a much greater binding activity to LCT than MIP based on HMDI (MIP-HMDI), and MIP-TDI displayed a remarkably specific binding to LCT (with an imprinting factor of around 3) in an acetonitrile/water (4:7 v/v) mixture. The adsorption of LCT by MIP-TDI reached equilibrium after 3 h; this demonstrated comparatively rapid adsorption kinetics. Also, MIP-TDI could be regenerated eight times at least; this implied that the robust β-CD polymer has the potential for practical applications. Furthermore, a cross-selectivity study indicated that the high adsorption of LCT and its analogues by MIP-TDI in aqueous media must have been ascribed to the cooperative effects of CD inclusion interaction and stereoshape memory. This study paved the way for the use of β-CD as a functional monomer for preparing smart artificial receptors for the efficient recognition of pyrethroids under aqueous conditions.