Preparation, functional characterization and hemostatic mechanism discussion for oxidized microcrystalline cellulose and its composites

Effective and affordable hemostatic materials are of great interests in the development of biomaterials. Lignocellulose, which is a raw material for microcrystalline cellulose, is one of the most economical and readily available polymers in the nature. The oxidized microcrystalline cellulose particles prepared in NO₂/CCl₄ oxidation system may be a type of affordable, effective and nontoxic hemostatic biomaterial. The FT-IR and ¹³C solid state NMR results showed that the hydroxyl groups on C6 of cellulose were highly selectively oxidized. The increase of carboxyl content and Zeta potential of OMCC were highly dependent on the oxidation time at the first 64 h. XRD spectra indicated that the crystallinity changed from 70.01 % (MCC) to 60.63 % (OMCC-96 h), and the particle size decreased to 80 µm (OMCC-96 h). To composite with oxidized regenerated cellulose gauze, the OMCC-64 h was optimal, based on the dramatically reduced DP value after 64 h oxidization. The results showed this novel composite with negative charge exhibited good hemostatic property and antibacterial activity. The composite was possessed of both the good biocompatibility for mouse endothelial cells in vitro and the superior biodegradation for rabbits in vivo. Moreover, the data of enzyme-linked immunosorbent assay and blood coagulation tests in vitro suggested that the composite could adsorb and activate the platelets, and then the platelet glycoprotein (GPIIb/IIIa) receptor became competent to bind soluble fibrinogen. The composite also greatly accelerated the activation of the blood coagulation factor XII, and promoted the generation of thrombin, so that the extrinsic route of blood coagulation was initiated.