Selective binding of heparin oligosaccharides in a magnetic thermoresponsive molecularly imprinted polymer.

Heparin is a highly sulfated polysaccharide, applied in clinic for treatment of thrombotic diseases. The biological activity is closely related to its molecular structure e.g. compositions of disaccharides and oligosaccharides units. The classical method to isolate the oligosaccharides after depolymerization by heparinases or nitrous acid I s by size exclusion chromatography which is a time-consuming process. In this study, we explored the possibility for rapid separation of oligosaccharides using a novel polymer material. The magnetic thermoresponsive molecularly imprinted polymers (MIPs) were synthesized using heparin disaccharide as a template, AEM, NIPAAm, and AAm as functional monomer, and MBAA as crosslinker by surface radical polymerization in an aqueous media. Incubation of the MIP with hepairn oligosaccharides demonstrated specific binding to the template molecule. This binding to the targeted molecule was affected by reaction temperature with regard to binding capacity and specificity. The recognition specificity and selectivity can be modulated by varying the compositions of multi-functional monomers. The pseudo-second-order kinetic model and Langmuir isotherm model provide the best fit to the equilibrium adsorption of heparin disaccharides by MIPs. The results suggest that the new material can be used for rapid separation of di- and tetra-saccharides of heparin, which can also be adapted to the applications for isolation of oligosaccharides from other polysaccharides, e.g. heparan sulfate and chondoriting sulfate.