Terminal sterilization of BisGMA-TEGDMA thermoset materials and their bioactive surfaces by supercritical CO2

The development of biomaterials endowed with bioactive features relies on a simultaneous insight into a proper terminal sterilization process. FDA recommendations on sterility of biomaterials are very strict: a sterility assurance level (SAL) of 10(-6) must be guaranteed for biomaterials to be used in human implants. In the present work, we have explored the potential of supercritical CO(2) (scCO(2)) in the presence of H(2)O(2) as a low-temperature sterilization process for thermoset materials and their bioactive surfaces. Different conditions allowing for terminal sterilization have been screened and a treatment time-amount of H(2)O(2) relationship proposed. The selected terminal sterilization conditions did not notably modify the mechanical properties of the thermoset nor of their fiber-reinforced composites. This was confirmed by μCT analyses performed prior to and after the treatment. On the contrary, terminal sterilization in the presence of H(2)O(2) induced a slight decrease in the surface hardness. The treatment of the thermoset material with scCO(2) led to a reduction in the residual unreacted monomers content, as determined by means of high performance liquid chromatography (HPLC) analyses. Finally, it was found that a thermoset coated with a polysaccharide layer containing silver nanoparticles maintained a very high antimicrobial efficacy even after the scCO(2)-based terminal sterilization.