Construction of anticoagulant poly (lactic acid) films via surface covalent graft of heparin-carrying microcapsules.

Heparin has been widely investigated in medicine and biomedical applications as an anticoagulant. This paper described a covalent modification of poly (lactic acid) (PLA) films with heparin-carrying microcapsules. The heparin-carrying microcapsules were achieved by layer-by-layer (LbL) self-assembly technology by which poly (allylamine hydrochloride) (PAH) and heparin were alternately coated on the Ca(2+)-cross-linked alginate hydrogel. The microcapsules were characterized by scanning electron microscopy (SEM), zeta potential analysis and Fourier transform infrared spectroscopy (FTIR), and then grafted to PLA films by -CONH- linkage between surface PLA molecules with residual primary amino groups on the outer PAH layer of microcapsules, in the presence of catalysts of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). SEM and FTIR revealed the formation of -CONH- linkage. In vitro antithrombogenicity by the method of the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) tests showed that surface-modified PLA films had superior coagulation properties to original PLA films. It is suggested that the present method would provide a potential effective tool for biomaterial modification.