Interactions between a biodegradable polymer, poly(hydroxybutyrate-hydroxyvalerate), proteins and macrophages

Abstract

The effect of the chemical and morphological modifications of the surface of poly(hydroxybutyrate-hydroxyvalerate) (92/8) (PHB/HV) films induced by an alkaline hydrolysis on the adsorption of three proteins known to modify cell behavior, namely albumin, collagen and fibronectin and on the adhesion and proliferation of monocytes-macrophages of the J774 cell line, has been studied. Before treatment, the water contact angle theta of the face that went through a corona pretreatment was higher than the other one. It increases with hydrolysis to equal the value of theta angle of the other face after 2 hours. The XPS analysis revealed that all the impurities present on the native material have been eliminated after hydrolysis leading to a similar chemical composition on both faces. The surface concentrations of -COOH functions accessible to [H-3]-lysine increases sharply with the duration of hydrolysis. The sharpest increase is observed at the very beginning of hydrolysis. The surface morphology of the polymer is also modified by hydrolysis. The adsorption of the three proteins increases when the polymer is hydrolyzed as well as the adhesion and proliferation of the monocytes-macrophages, no matter which protein was adsorbed. There are some evidence suggesting that the protein conformation is different on both substrates. Collagen has a drastic repulsive effect on the cells on the native polymer but this repulsive effect disappeared on the hydrolysed one. Accordingly, it clearly appears that it is possible to modulate the biocompatibility of PHB/HV by either chemical hydrolysis or protein adsorption