Template-directed preparation of three-dimensionally ordered macroporous molecularly imprinted microspheres for selective recognition and separation of quinine from cinchona extract

Abstract

A kind of novel three-dimensionally ordered macroporous molecularly imprinted microspheres (3DMIMs) had been developed for selective recognition and separation of quinine based on the combination of colloidal crystal templating method and molecular imprinting technique. The 3DMIMs were derived from the spherical silica colloidal crystal involving a four-step templating process including infiltration of imprinted precursors, sealing of polyethylene glycol, initiation polymerization, as well as final removal of the colloidal crystal and imprinting template. The resulted 3DMIMs consisted of a three-dimensional, highly ordered and interconnected macroporous arrays with nanoscale thickness of polymer wall, in which numerous imprinted cavities were obtained. The kinetic and isothermal adsorption behavior of the 3DMIMs were investigated in detail. The results showed the 3DMIMs had a rapider mass transfer process, higher adsorption capacities and recognition specificity toward quinine compared with the traditional bulk imprinted polymers. In addition, the 3DMIMs exhibited obvious high permeability and low backpressure at high flow rate as column packing. Extraction experiments showed that the 3DMIMs could effectively separate quinine and its diastereoisomer, quinidine, directly from crude cinchona bark extract with a satisfactory selectivity and elution recovery.