Constituting of a new surface‐initiating system on polymeric microspheres and preparation of basic protein surface‐imprinted material in aqueous solution

Abstract

In this work, a new surface‐initiating system was constituted on the surfaces of cross‐linked polyvinyl alcohol (CPVA) microspheres, and on this basis, papain surface‐imprinted material was successfully prepared in aqueous solution. CPVA microspheres were modified with chlorethamin as reagent, and so a mass of primary amino group was introduced onto CPVA microspheres. Whereupon, a surface initiating system (−NH2/S2O82−) was formed at the interface between the microspheres and aqueous solution, in which papain as template protein, 4‐styrene sulfonate (SSS) as functional monomer, N,N′‐methylenebisacrylamide (MBA) as cross‐linker and (NH4)2S2O8 as initiator were all dissolved. In neutral solution, the polypeptide chains of papain as a basic protein were positively charged, and the molecules of anionic monomer SSS would spontaneously gather around papain polypeptide chain, forming complex by right of strong electrostatic interaction. The free radicals produced on CPVA microspheres initiated the monomer SSS around papain polypeptide chain and the cross‐linker MBA to produce graft/cross‐linking polymerization, and at the same time, papain macromolecules were embed in the cross‐linked networks. As a result, the graft/cross‐linking polymerizing of SSS and the molecule imprinting of papain were synchronously carried out, and papain surface‐imprinted material, MIP‐PSSS/CPVA microspheres, was obtained. The experimental results show that the papain surface‐imprinted material has excellent binding affinity and high recognition selectivity for papain. The binding capacity of MIP‐PSSS/CPVA microspheres for papain reaches 44 mg/g, and relative to another basic protein, trypsin (TRY) as contrast protein, the selectivity coefficient of MIP‐PSSS/CPVA microspheres for papain is 14.35, displaying very high recognition specificity.