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

Abstract

a b s t r a c tThe kinetics of bacterial reduction of Staphylococcus aureus (MRSA) on co-sputtered TiO 2 /Cu-polyester (TiO 2 /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. TiO 2 /Cu-PES obtained by direct current magnetron co-sputtering and the bacterial reduction features compared to PES sputtered individually by TiO 2 and Cu. This study presents the first evidence for the stabilizing effect of TiO 2 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 TiO 2 /Cu led to a 5 log 10 (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 TiO 2 /Cu surfaces investigated in this study.

Indoor Light Enhanced Photocatalytic Ultra-Thin Films on Flexible Non-Heat Resistant Substrates Reducing Bacterial Infection Risks

“…A thickness of 38 nm was required to inactivate bacteria within~10 min on the HIPIMS film compared with a thickness layer of 600 nm when applying DCMS/DCMSP. A big difference was also seen (2) sequentially sputtered using DCMS deposition [57,67] and (3) co-sputtered using DCMS [66] deposition.…”

“…The HIPIMS charge density higher than in DCMSP by two orders of magnitude and comprises pulses ~60 times more energetic than the ones applied by DCMSP [67]. Figure 8 shows that thinner films deposited by HIPIMS exhibit fast bacterial inactivation kinetics.…”

New evidence for Cu-decorated binary-oxides mediating bacterial inactivation/mineralization in aerobic media

“…The treatment of the IR data has been already reported, and therefore will not be addressed in detail in the present study [24,25]. The shift peaks reflect an increasing C C bond distance increasing with the time of irradiation introducing structural disorder in the outer lipo-polysaccharide layers (LPS) of E. coli [26,27]. This concomitant increased stretching leads to a more fluid LPS bilayer until the −CH 2 -scission sets in after 120 min for TiO 2 -ZrO 2 and after 45 min for TiO 2 -ZrO 2 -Cu in agreement with the bacterial inactivation times reported in Fig.…”

Recent Developments in Accelerated Antibacterial Inactivation on 2D Cu-Titania Surfaces under Indoor Visible Light

“…The surface composition and properties of the TiO 2 -CuO play a role in the charge transfer kinetics involving: (a) surface defects; (b) surface imperfections; and (c) dangling bonds on the edge of this composite. Using XPS and atomic force microscopy (AFM), information on the surface composition and roughness has been partially reported [169]. In TiO 2 -Cu the charge recombination is short due to their small particle size.…”

“…Figure 12 trace 1 shows bacterial inactivation within 30 min for TiO 2 -Cu co-sputtered for 3 min. This film was determined by profilometry to be 135 nm thick (about 700 atomic layers) consisting of 0.16% Cu weight/TiO 2 0.14% by weight on PES as determined by X-ray fluorescence (XRF) on the PES substrate [169]. This coating provides a sufficient amount of TiO 2 and Cu on the PES to interact meaningfully with bacteria.…”