SCF-assisted processing of dexamethasone-loaded poly(ε-caprolactone)/MCM-41 materials for biomedical applications

Biodegradable polymeric foams of proper pore sizes, geometries and densities, are already known to be useful biomaterials for several pharmaceutical, biomedical and tissue engineering applications. Moreover, the combination of these biodegradable polymeric foams with biocompatible inorganic nanoparticles and with bioactive substances may lead to the generation of novel composite biomaterials presenting improved chemical, physical and biological properties. This work reports preliminary results on the use of supercritical carbon dioxide (scCO2) processes, namely of scCO2-assisted foaming and of scCO2-assisted impregnation/deposition, for the development of dexamethasone-loaded composite biomaterials prepared with poly(E-caprolactone) (PCL) and with mesoporous MCM-41 silica nanoparticles (SNPs). Pure PCL and PCL/MCM-41 composite materials (90:10 and 70:30, wt.%) were processed by scCO2 foaming at different experimental density (801.4 and 901.2 Kg/m3), processing time (2 and 14 hours) and depressurization rate (0.22 and 3.0 L/min) conditions. In addition, mesoporous MCM-41 SNPs were loaded with dexamethasone (DXMT) by a scCO2 impregnation/deposition method at the above referred experimental conditions, and by DXMT sorption from aqueous and from ethanolic DXMT liquid solutions (at 37 oC and atmospheric pressure). All prepared materials were characterized by simultaneous differential thermal analysis (SDT) and texturometry. DXMT release studies were performed in order to evaluate and to compare the obtained DXMT release profiles from loaded MCM-41 SNPs. Obtained results demonstrated the feasibility of using scCO2 impregnation/deposition and scCO2 foaming methods for the development of DXMT-loaded PCL/MCM-41 composite materials to be applied in hard tissue biomedical applications.