Albumin grafting on to polypropylene by thermal activation

Abstract

4-azido-2-nitrophenyl albumin (ANP-albumin) was prepared by reacting 4-fluoro-3-nitrophenyl azide with albumin. The thermal decomposition kinetics of phenyl azide of ANP-albumin was studied at various temperatures by Fourier-Transform Infrared (FTIR) spectroscopy. The decomposition rate of the phenyl azide increased with temperature. The activation energy for the first-order decomposition of the phenyl azide was 128.0 kJ/mol. Albumin was grafted on to polypropylene (PP) films by thermolysis of the azido groups of ANP-albumin with no premodification of the PP surface. The albumin-grafted surface was characterized by electron spectroscopy for chemical analysis (ESCA) and by quantitative determination of platelet adhesion and activation. The bulk concentration of ANP-albumin used for adsorption varied from 0.001 to 30 mg ml −1, and the albumin-adsorbed PP films were incubated at 100°C for up to 7 h. The carbon and nitrogen peaks resulting from the grafted albumin were used to compare the surface albumin concentrations as a function of the concentration of ANP-albumin in the adsorption solution. When the PP film was adsorbed with ANP-albumin at the concentration of 5 mg ml −1 or higher and incubated at 100°C for longer than 5 h, the surface became resistant to platelet adhesion. The ANP-albumin can be grafted on to chemically inert surfaces such as PP surface through simple thermolysis of azido groups to prevent platelet adhesion and activation.