Combined sterilization and fabrication of drug-loaded scaffolds using supercritical CO₂ technology

The access of biodegradable scaffolds to the clinical arena is constrained by the absence of a suitable sterilization technique for the processing of advanced polymeric materials. Sterilization with supercritical CO₂ (scCO₂) may circumvent some technological limitations (e.g., low temperature, no chemical residues on the material), although scCO₂ can plasticize the polymer depending on the processing conditions used. In this latter case, the integration of the manufacturing and sterilization processes is of particular interest to obtain sterile and customized scaffolds in a single step. In this work, scCO₂ was exploited as a concomitantly foaming and sterilizing agent for the first time, developing a one-step process for the production of vancomycin-loaded poly(ε-caprolactone) (PCL) bone scaffolds. The effect of the CO₂ contact time on the sterility levels of the procedure was investigated, and the sterilization efficiency was evaluated against dry spores (Bacillus stearothermophilus, Bacillus pumilus and Bacillus atrophaeus). Vancomycin-loaded PCL scaffolds had relevant sustained release profiles for the prophylaxis of infections at the grafted area, even those caused by methicillin-resistant Staphylococcus aureus (MRSA). The biological performance of the scaffolds was evaluated in vitro regarding human mesenchymal stem cells (hMSCs) attachment and growth. Finally, the biocompatibility and angiogenic response of the manufactured sterile scaffolds was assessed in ovo through chick chorioallantoic membrane (CAM) assays.