Comparative study of biomaterial surface modification due to subcritical CO2 and autoclave disinfection treatments

The decontamination of medical tools is a sustainable alternative to the use of disposable items. Sub- and supercritical fluids can be applied to decontaminate the surfaces of most biomedical materials with relative instrumental simplicity and moderate capital and operational costs, and offers a promising alternative to autoclavation. For future adaption it is important to assess the extent of material surface degradation, since CO2 has corrosion potential against metals and is soluble in polymers, and also forms a weak acid in the presence of residual humidity. Experimental results are reported for subcritical CO2 (37 oC, 50 bar, 2 h) decontamination of surgical stainless steel, Ti-6Al-4V alloy, PEEK polymer, ZrO2 ceramic and natural tooth enamel specimens seeded with E. coli, St. aureus, Pr. intermedia and C. albicans sealed inside polymer-paper packages during 1, 2, 5 and 10 cycles of treatment. Characterization by SEM and nanoindentation revealed that detectable alterations could be found only after the first cycle of treatment, whilst subsequent 10 treatment cycles did not cause further change. The findings provide a good basis for ongoing research into the potential of the supercritical fluid decontamination. [Display omitted] •Subcritical (50 bar) CO2 disinfection at 37 °C was successful for four bacteria and fungi cultures.•120 min subcritical CO2 treatment showed successful disinfecting effect on titanium alloy discs inside sealed craft packages.•The effects of repeated subcritical CO2 disinfection and autoclavation (at 132 °C) were compared for biomedical material surfaces.•Surface property modification of disinfected biomedical materials was assessed by nanoindentation.