Supercritical CO2 technology for one-pot foaming and sterilization of polymeric scaffolds for bone regeneration

Sterilization is a quite challenging step in the development of novel polymeric scaffolds for regenerative medicine since conventional sterilization techniques may significantly alter their morphological and physicochemical properties. Supercritical (sc) sterilization, i.e. the use of scCO(2) as a sterilizing agent, emerges as a promising sterilization method due to the mild operational conditions and excellent penetration capability. In this work, a scCO(2) protocol was implemented for the one-pot preparation and sterilization of poly(epsilon-caprolactone) (PCL)/ poly(lactic-co-glycolic acid) (PLGA) scaffolds. The sterilization conditions were established after screening against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) vegetative bacteria and spores of Bacillus stearothermophilus, Bacillus pumilus and Bacillus atrophaeus. The transition from the sterilization conditions (140 bar, 39 degrees C) to the compressed foaming (60 bar, 26 degrees C) was performed through controlled depressurization (3.2 bar/min) and CO2 liquid flow. Controlled depressurization/pressurization cycles were subsequently applied. Using this scCO(2) technology toolbox, sterile scaffolds of well-controlled pore architecture were obtained. This sterilization procedure successfully achieved not only SAL-6 against wellknown resistant bacteria endospores but also improved the scaffold morphologies compared to standard gamma radiation sterilization procedures.

Automated summary

A supercritical CO2 sterilization protocol was successfully implemented to prepare and sterilize polymeric scaffolds for regenerative medicine. The sterilization conditions were established after screening against various bacteria and spores, and a transition to compressed foaming was achieved through controlled depressurization. Using this technology, sterile scaffolds with well-controlled pore architecture were obtained, surpassing standard gamma radiation sterilization methods.