Surface molecular imprinting onto magnetic yeast composites via atom transfer radical polymerization for selective recognition of cefalexin

In this study, the magnetic yeast composites (mag-yeast) were successfully prepared by coating the chitosan layer containing gamma-Fe2O3 nanoparticles onto the surface of the yeast. Then, the magnetic molecularly imprinted polymers (MMIPs) based on the mag-yeast were prepared by atom transfer radical polymerization (ATRP) which was occurred in mild reaction conditions. The MMIPs were characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA) and elemental analysis. The results demonstrated that spherical shaped MMIPs particles prepared via ATRP possessed magnetic property (M-s = 1.229 emu g(-1)) and magnetic stability (especially over the pH range of 5.0-11.0). The MMIPs were adopted as sorbents to selective recognition and separation of cefalexin (CFX). By the batch mode experiments, the results showed that adsorption behaviors of MMIPs were well described by the Freundlich isotherm and the pseudo-second-order kinetics. The MMIPs possessed excellent recognition capacity for CFX (36.86 mg g(-1) at 298 K), and also exhibited outstanding selectivity for CFX over the other competitive compounds (such as sulfadiazine, tetracycline and ampicillin). Finally, the MMIPs were successfully applied to the selective solid phase extraction of CFX from the environmental samples. (C) 2012 Elsevier B.V. All rights reserved.