Synthesis of porous zwitterionic sulfobetaine monoliths and characterization of their interaction with proteins

New synthesis routes for incorporation of zwitterionic sulfobetaine groups into porous polymeric monoliths have been developed. The first approach involved photoinitiated copolymerization of N,N-dimethyl-N-methacryloxyethyl-N-(3-(sulfopropyl)ammonium betaine (SPE) and ethylene dimethacrylate. (EDMA) as cross-linker. Alternatively, the internal surfaces of porous poly(trimethylolpropane trimethacrylate) (poly-TRIM) monoliths were provided with zwitterionic "combs" by thermally initiated grafting of poly-SPE chains. The grafted monoliths exhibited an electrolyte responsive flow permeability, whereas the permeability of the copolymerized monoliths was unaffected by changes in ionic strength in the interval tested. Both synthesis routes yielded polymers capable of interacting reversibly with proteins in aqueous solutions, thus paving the way for novel selectivity dimensions in the field of bioseparations. This report also reveals the possibility of modulating the protein-polymer interaction strengths over a wide range on monolithic zwitterionic sorbents, by addition of low concentrations of a chaotropic ion to the aqueous phase.