Biocompatibility and biodegradation of polycaprolactone-sebacic acid blended gels

Tissue engineering aims at creating biological body parts as an alternative for transplanting tissues and organs. A current new approach for such materials consists in injectable biodegradable polymers. Their major advantages are the ability to fill-in defects, easy incorporation of therapeutic agents or cells, and the possibility of minimal invasive surgical procedures. Polycaprolactone (PCL) is a promising biodegradable and elastic biomaterial, with the drawback of low-degradation kinetics in vivo. In this work a biodegradable injectable gel of PCL blended with sebacic acid (SA) was prepared, to improve the degradation rate of the biomaterial. SA is known for its high degradation rate, although in high concentrations it could originate a pH decrease and thus disturb the biocompatibility of PCL. Degradation tests on phosphate buffered saline were carried out using 5% of SA on the blend and the biomaterial stability was evaluated after degradation using differential scanning calorimetry, dynamical mechanical analysis, and scanning electronic microscopy. After degradation the elastic properties of the blend decreased and the material became more crystalline and stiffer, although at a lower extent when compared with pure PCL. The blend also degraded faster with a loss of the crystalline phase on the beginning (30 days), although its thermal and mechanical properties remained comparable with those of the pure material, thus showing that it achieved the intended objectives. After cell assays the PCL-SA gel was shown to be cytocompatible and capable of maintaining high cell viability (over 90%).