Duality in the Escherichia coli and methicillin resistant Staphylococcus aureus reduction mechanism under actinic light on innovative co-sputtered surfaces

• E. coli reduction was significantly dependent on the applied light dose.
• MRSA reduction was not observed to be dependent on the applied light dose.
• TiO2 was shown to slow down the Cu release from the TiO2/Cu-PES surface.
• Cu release from TiO2/Cu-PES during bacterial reduction suggests an oligodynamic effect.
• MRSA reduction on TiO2/Cu-PES was within 120 min in the dark and 60 min under light.

The kinetics of bacterial reduction of Staphylococcus aureus (MRSA) on co-sputtered TiO2/Cu-polyester (TiO2/Cu-PES) was found to be little dependent on the applied light dose. But in the case of Escherichia coli, the bacterial reduction kinetics was observed to be strongly dependent on the applied light dose. The reasons for the different effect of the applied light dose on the bacterial reduction are discussed. Mechanistic considerations are suggested to account for this observation. TiO2/Cu-PES obtained by direct current magnetron co-sputtering and the bacterial reduction features compared to PES sputtered individually by TiO2 and Cu. This study presents the first evidence for the stabilizing effect of TiO2 on the amounts of the Cu released during bacterial inactivation by co-sputtered surfaces compared to sequential sputtering of Ti and/or Cu on PES. The release of Cu-monitored in the ppb range by inductively coupled plasma-mass spectrometry (ICP-MS) is indicative of an oligodynamic effect leading to bacterial reduction. The bacterial reduction of MRSA ATCC 43300 on co-sputtered TiO2/Cu led to a 5 log10 (99.999%) reduction within 120 min in the dark and 60 min under low intensity actinic light. Diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and X-ray fluorescence (XRF) describe the TiO2/Cu surfaces investigated in this study.

Figure optionsDownload high-quality image (307 K)Download as PowerPoint slide