Surface modification of PVDF membranes with quaternized chitosan for selective separation of negatively charged polysaccharides – exemplified with heparin

Abstract

Several animal polysaccharides, e.g. heparin, are industrially produced for clinical applications. Isolation of these molecules involves multi-step purification process including polycationic adsorbents adsorption and the removal of macromolecular impurities, e.g. protein, causing time-consuming and environmental pollution. In this study, a novel quaternized chitosan@PVDF/SiO2 (QCCS@PS) membrane was fabricated for selective separation of heparin while simultaneously rejecting protein through an efficient one-step separation. A series of characterization results confirmed that the membranes were successfully fabricated. The QCCS@PS membrane exhibited an adsorption capacity to heparin at various pH. The adsorption curve fitting results showed that the adsorption process was more consistent with the PFO kinetic model. Zeta potential and X-ray photo-electron spectroscopy results indicated heparin could be attracted to the surface of the QCCS@PS membrane via electrostatic interaction by -N(CH3)3+ groups of the membrane. A comparable separation performance of heparin and protein was obtained for the prepared membranes. The results indicated the selectivity factor of heparin to BSA could be improved from 2.49 to 11.08 by using the QCCS@PS membrane due to electrostatic attraction to heparin and electrostatic repulsion to BSA. Furthermore, the membrane could be practically applied in selective separation and purification heparin from crude heparin. Thus, this positively charged membrane technology could be applied for the green, efficient and selective separation of heparin, as well as other negatively charged polysaccharides.