Sequential scCO2 drying and sterilisation of alginate-gelatine aerogels for biomedical applications

Abstract

The supercritical CO2 (scCO2) drying and sterilisation of alginate-gelatine aerogels were performed in a continuous and integrated process. After drying, two sterilisation conditions were used: 100 and 250 bar pressure differentials (∆p), also using a pouch when considered the final sterilisation. Chemical and thermal analysis showed that unlike autoclaving (a sterilisation comparison method), scCO2 sterilisation did not lead to aerogel degradation. Porosity, pore diameter and surface area decreased with increasing ∆p during scCO2 sterilisation, while the mechanical properties were preserved when the lower ∆p was applied. In autoclaved matrices, the pores collapsed as expected. Microbiological analysis proved the efficiency of the integrated scCO2 drying and sterilisation, as both ∆p were able to eliminate natural contaminant microorganisms (e.g., Bacillus spp.) from the aerogels. In the end, this innovative strategy made it possible to obtain ready-to-use sterilised natural-based aerogels with the potential to be applied in regenerative medicine.