Fabrication of thromboresistant multilayer thin film on plasma treated poly (vinyl chloride) surface.

Layer-by-layer deposited anticoagulant multilayer films were prepared on ammonia plasma treated poly (vinyl chloride) (PVC). Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and contact angle results revealed the presence of -NH2 on the ammonia plasma treated PVC surfaces and the layer-by-layer self-assembly process. The stability of multilayer film was studied with the radio labeled method. The remainder bovine serum albumin (BSA) in cross-linked 5(heparin/BSA) multilayer films dipped in phosphate buffered saline (PBS, pH 7.4) was more than 90% in 40 days. The static platelet adhesion result indicated the anticoagulant multilayer films deposited on the plasma treated PVC reduced platelet adhesion drastically and no thrombus forming. The plasma recalcification time revealed that the multilayer modified surfaces greatly prolonged the plasma recalcification time. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.

A novel crosslinkable polymer as drug-loaded coating for biomedical device.

A novel copolymer has been synthesized by the radical polymerization of poly (ethylene oxide) methacrylate, stearyl methacrylate, hydroxypropyl methacrylate and trimethoxysilylpropyl methacrylate. The polymer was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy and gel permeation chromatography. The crosslinkable coating was prepared by dip-coating 5mg/ml solution in tetrahydrofuran onto glass substrate. A stable crosslinked coating was obtained after curing the coating at 70 degrees C for 9 h. Contact angle results indicated the possible reorganization of the surface amphiphilic molecule which interpreted the excellent biocompatibility revealed by the results of the platelet adhesion and plasma recalcification time. Rhodamine S and Cibacron Blue were used as model drugs to prepare drug-containing coating at the same conditions. Drug-releasing curves indicated that the mechanism of the release is approximately Fickian release.

Fabrication of alternating polycation and albumin multilayer coating onto stainless steel by electrostatic layer-by-layer adsorption.

Multilayer films consisting of polyethylenimine (PEI) and albumin were successfully prepared on biomedical 316L stainless steel surface via electrostatic self-assembly of the PEI and albumin. The process of electrostatic self-assembly of PEI/albumin was monitored by125I radiolabeling, electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The EIS data revealed that the multilayer coating was stable in Tris-HCl (pH 7.35) buffer solution for 21 days. 125I radiolabeling experiments indicated that less than 10% albumin was eluted by PBS in 45 days. Static platelet adhesion experiments indicated that the PEI/albumin deposited on stainless steel could resist platelet adhesion effectively. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.