INTERACTIONS BETWEEN A BIODEGRADABLE POLYMER, POLY(HYDROXYBUTYRATE-HYDROXYVALERATE), PROTEINS AND MACROPHAGES

The effect of the chemical and morphological modifications of the surf ace of poly(hydroxybutyrate-hydroxyvalerate) (92/8) (PHB/HV) films ind uced by an alkaline hydrolysis on the adsorption of three proteins kno wn to modify cell behavior, namely albumin, collagen and fibronectin a nd on the adhesion and proliferation of monocytes-macrophages of the J 774 cell line, has been studied. Before treatment, the water contact a ngle theta of the face that went through a corona pretreatment was hig her than the other one. It increases with hydrolysis to equal the valu e of theta angle of the other face after 2 hours. The XPS analysis rev ealed 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 accessib le 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 hy drolyzed as well as the adhesion and proliferation of the monocytes-ma crophages, no matter which protein was adsorbed. There are some eviden ce suggesting that the protein conformation is different on both subst rates. Collagen has a drastic repulsive effect on the cells on the nat ive polymer but this repulsive effect disappeared on the hydrolysed on e. Accordingly, it clearly appears that it is possible to modulate the biocompatibility of PHB/HV by either chemical hydrolysis or protein a dsorption.