Switchable zipper-like thermoresponsive molecularly imprinted polymers for selective recognition and extraction of estradiol

Abstract

Zipper-like thermoresponsive molecularly imprinted polymers (MIPs) were prepared based on interpolymer complexation via the synergy of dual functional monomers of acrylamide (AAm) and 2-acrylamide-2-methyl propanesulfonic acid (AMPS) for selective recognition and extraction of estradiol (E2) by temperature regulation. The resulting E2-MIPs attained controlled adsorption and release of E2 in response to temperature change, with higher adsorption capacity (8.78mg/g) and stronger selectivity (imprinting factor was 3.18) at 30°C compared with that at 20 and 40°C; the zipper-like interpolymer interaction between poly(AAm) and poly(AMPS) enabled switchable molecular recognition. The adsorption processes obeyed Langmuir isotherm and pseudo-second-order kinetic models. High recognition selectivity of the MIPs toward E2 was achieved over its structural analogues, and good reusability was displayed over 86% recovery after six adsorption-desorption cycles. Accordingly, the E2-MIPs were empolyed as new adsorbents for selective dispersive solid-phase extraction of E2, and offered low limits of detection and quantification of 4.81 and 16.03μg/L, respectively. Recoveries from goat milk samples ranged from 76.2% to 89.7% with the precisions (relative standard deviations, n = 3, %) of 2.8-3.7% at 30°C. The intelligent E2-MIPs combining good adsorption, special recognition and temperature sensitivity proved to be a promising alternative to the selective identification and controlled extraction/removal of E2 in complicated samples by simple temperature-responsive regulation.

Keywords: Dispersive solid-phase extraction; Estradiol; Molecularly imprinted polymers; Thermoresponsive; Zipper-like.