Supercritical processing of starch aerogels and aerogel-loaded poly(ε-caprolactone) scaffolds for sustained release of ketoprofen for bone regeneration

Abstract

Bone regeneration requires scaffolds with a suitable nanostructured 3D-network and decorated with bioactive functionalities to promote cell ingrowth and induce the intended biological responses. In this work, highly porous poly(ε-caprolactone) (PCL) scaffolds containing biodegradable mesoporous microparticles (starch aerogel microspheres) and a bioactive compound (ketoprofen, a NSAID) were designed and produced using supercritical technologies (scCO2 impregnation/deposition and foaming) for bone regeneration purposes. One-micron-sized starch aerogel microspheres were processed for the first time. The effects of the incorporation of aerogel powders in the synthetic PCL-based scaffolds on the morphological, physico-chemical and mechanical properties of the construct were evaluated by N2 adsorption-desorption analysis, scanning electron microscopy, mercury intrusion porosimetry, 3D-modeling, dynamic mechanical analysis and differential scanning calorimetry methods. Scaffolds containing starch aerogels presented an increased porosity and pore interconnectivity to promote the bone tissue growth processes at the expense of a minor decrease in the mechanical properties. The scaffolds showed sustained release of ketoprofen (37°C, pH 7.4) in the timeframe of days with faster release rate in the case of scaffolds containing starch aerogels. Therefore, scaffolds containing starch aerogel microspheres and obtained by supercritical foaming are an attractive solution to obtain drug-loaded scaffolds with accurate pore structure (porosity, pore size distribution, interconnectivity) for cell in-growth and with sustained release profiles of bioactive compounds.