Amine Selmani

Processing Biodegradable Natural Polyesters for Porous Soft-Materials

Absorbable polymeric scaffolds have been recently experimented for cell culture and transplantation, tissular reconstruction and In-Vivo drug or protein release. In the present work, the building of artificial porous soft-material is proposed by salt-leaching/solvent-casting a microbial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) polyester. The electron microscopy and mercury porosimetry show a highly-porous well-interconnected micro-structures with a porosity level of 0.85 and a mean pore diameter of 122nm. The weight loss of the porous structures is about 50% for a 140 days period of hydrolytic degradation in Phosphate Buffered Solutions, pH 7.4 at 70°C. Incubations from 1 to 35 days of canine Anterior Cruciate Ligaments (ACLs) fibroblasts in P(HB-HV) scaffolds have shown a limited proliferation rate (150xl06 cells/g maximal density), but high protein synthesis (2.4+/-0.1 x1O-2 ng/cell.day at day 28th). Future studies on biodegradable P(HB-HV) foams will evaluate more deeply the potential applications for orthopaedic reconstructions.

Effect of plasma treatment on tribological properties of synthetic ligaments.

The objective of this study was to determine the optimal experimental conditions for plasma treatment of polyester ligaments. Two different surface modification techniques were used: tetrafluoroethylene and methane. Gas flow rate, pressure, power, and treatment period giving a thin film with low friction coefficient and low surface energy was determined. Control and plasma treated surfaces were characterized by X-ray photoelectron spectroscopy to investigate the functionalization of the treated surfaces in detail. The surface tension of control and plasma treated surfaces were determined from contact angle measurements to understand the adhesion and reactivity of films with aqueous medium. The results showed a decrease in friction coefficient from 0.45 to 0.28 and from 0.45 to 0.26 for thin films deposited respectively by tetrafluoroethylene (TFE) and methane (CH4) plasma. Contact angles increased from 63 degrees to 120 degrees for TFE plasma and from 63 degrees to 93 degrees for CH4 plasma. Large contact angles mean a weak affinity between molecules in water/material phase, so that the power to attract cells to the surface of the material is too weak. The results showed that optimal film, i.e., low static friction coefficient and large contact angle, can be obtained by a CH4 plasma treatment at high power RF. For TFE plasma treatments, a low power RF is needed to obtain a thin film with a stable chemical structure.