A strategy of improving the imprinting effect of molecularly imprinted polymer: Effect of heterogeneous macromolecule crowding.

The topic in the present work is to prepare molecularly imprinted polymer (MIP) in heterogeneous crowding surrounding for improving imprinting effect. For the first time, heterogeneous crowding surrounding was made up of a tetrahydrofuran (THF) solution of low molecular weight polyethene glycol (PEG) and high molecular weight polystyrene (PS). The MIP prepared in heterogeneous crowding surrounding against procyanidin B2 can display apparent imprinting effect (imprinting factor of 5.13) in the situation of difficult imprinting at single crowding surrounding or non-crowding surrounding. The necessity of simultaneous use of low and high molecular weight crowding agents for enhanced imprinting effect was further proved. NMR peak shifts of active hydrogen of procyanidin B2 strongly suggested that the interaction between functional monomer and template can be enhanced due to the effect of heterogeneous crowding in the self-assembly process. The influence of molecular weight and amount of PEG, molecular weight of PS, as well as the ratio of procyanidin B2 to functional monomer on the imprinting factor was investigated. The MIP was then used to extract purify procyanidin B2 from extract of grape seed. The recovery of procyanidin B2 obtained was 87% with relative standard deviation of less than 5%.