In this study, the photoreactivation and the modification of dark repair of E. coli in a simulate... more In this study, the photoreactivation and the modification of dark repair of E. coli in a simulated secondary effluent were investigated after initial irradiation under different conditions. The simulated solar exposure of the secondary wastewater was followed by exposure to six different low-intensity fluorescent lamps (blacklight blue, actinic blacklight, blue, green, yellow and indoor light) for up to 8 h. When photoreactivation was monitored, blue and green colored fluorescent light led to increased bacterial regrowth. Blacklight lamps further inactivated the remaining bacteria, while yellow and indoor light led to accelerated growth of healthy cells. Exposure to fluorescent lamps was followed by long term storage in darkness, to monitor the bacterial repair in the dark. The response was correlated with the pre-exposure dose of applied solar irradiation, and to a lesser extent with the fluorescent light dose. Bacteria which had undergone extensive exposure showed no response under fluorescent light or during storage in the dark. Finally, the statistical treatment of the data allowed us to suggest a linear model, which is non-selective in terms of the fluorescent light applied. The estimation of the final bacterial population was predicted well (R-sq ∼ 75%) and the photoreactivation risk was found to be more important for cultivable cells.
Polyethylene-TiO 2 (from now on PE-TiO 2 ) transparent, non-scattering sputtered films have been ... more Polyethylene-TiO 2 (from now on PE-TiO 2 ) transparent, non-scattering sputtered films have been found effective in the discoloration of methylene blue (MB) under low intensity solar simulated light. By Fourier transform attenuated infrared spectroscopy (ATR-FTIR), the systematic shift and decrease in the s (CH 2 ) and s (C C) vibration-rotational bands was observed preceding MB discoloration. RF-pretreatment allowed a significant increase in the TiO 2 loading on PE compared to non-pretreated PE as shown by X-ray fluorescence (XRF). The PE-TiO 2 photo-switching from a hydrophobic to a hydrophilic surface was observed within 60 min under light while the reverse process was complete within 24 h in the dark. The position of the MB* and MB*/MB + levels allowing electron injecting into the TiO 2 cb is discussed. The probability for the MB T deactivation and of MB* reacting with O 2 leading to the short lived MB + cation is estimated. A mechanism for MB discoloration on PE-TiO 2 is suggested.
Antibacterial robust, uniform TiO 2 -ZrO 2 films on polyester (PES) under low intensity sunlight ... more Antibacterial robust, uniform TiO 2 -ZrO 2 films on polyester (PES) under low intensity sunlight irradiation made up by equal amounts of TiO 2 and ZrO 2 exhibited a much higher bacterial inactivation kinetics compared to pure TiO 2 or ZrO 2 .
This study addresses the preparation and characterization of hybrid films prepared from Titanium ... more This study addresses the preparation and characterization of hybrid films prepared from Titanium dioxide (TiO 2 ) Pickering stabilized acrylic polymeric dispersion as well as their bacterial inactivation efficiency under sunlight irradiation. Complete bacterial inactivation under low intensity simulated solar light irradiation (55 mW/cm 2 ) was observed within 240 min for the films containing 10 weight based on monomers (wbm) % of TiO 2 , whereas 360 min were needed for the films containing 20 wbm% of TiO 2. The hybrid films showed repetitive Escherichia coli (E. coli) inactivation under light irradiation. TiO 2 released from the films surfaces was measured by inductively coupled plasma mass spectrometry (IPC-MS), obtaining values of ∼0.5 and 1 ppb/cm 2 for the films containing 10 wbm% and 20 wbm% of TiO 2 , respectively, far below the allowed cytotoxicity level for TiO 2 (200 ppb). Transmission electron microscopy (TEM) of the hybrid films showed that TiO 2 nanoparticles (NPs) were located at the polymer particle's surface forming a continuous inorganic network inside the film matrix. Atomic force microscopy (AFM) images showed differences in the TiO 2 dispersion between the air-film and film-substrate interfaces. Films containing 10 wbm% of TiO 2 had higher roughness (Rg) at both interfaces than the one containing 20 wbm% of TiO 2 inducing an increase in the bacterial adhesion as well as the bacterial inactivation kinetics. The highly oxidative OH • -radicals participating in the bacterial inactivation were determined by fluorescence.
The kinetics of bacterial reduction of Staphylococcus aureus (MRSA) on co-sputtered TiO 2 /Cu-pol... more The 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.
Evidence is presented for radio-frequency plasma pretreatment enhancing the amount and adhesion o... more Evidence is presented for radio-frequency plasma pretreatment enhancing the amount and adhesion of TiO2 sputtered on polyester (PES) and on polyethylene (PE) films. Pretreatment is necessary to attain a suitable TiO2 loading leading to an acceptable Escherichia coli reduction kinetics in the dark or under light irradiation for PES-TiO2 and PE-TiO2 samples. The amount of TiO2 on the films was monitored by diffuse reflectance spectroscopy and X-ray fluorescence. X-ray electron spectroscopy shows the lack of accumulation of bacterial residues such as C, N and S during bacterial inactivation since they seem to be rapidly destroyed by TiO2 photocatalysis. Evidence was found for Ti(4+)/Ti(3+) redox catalysis occurring on PES-TiO2 and PE-TiO2 during the bacterial inactivation process. On PE-TiO2 surfaces, Fourier transform infrared spectroscopy (ATR-FTIR) provides evidence for a systematic shift of the na(CH2) stretching vibrations preceding bacterial inactivation within 60 min. The discon...
The bacteria inactivation of E. coli by Ag colloidal loaded cotton and polyester was investigated... more The bacteria inactivation of E. coli by Ag colloidal loaded cotton and polyester was investigated. Textile surfaces were pretreated by RF-plasma and UVC to introduce organic-polar groups containing oxygen functionalities binding/complexing/chelating Ag-clusters. Since sol-gel films are not mechanically stable, only exhibit low adhesion and can be wiped off by a cloth or thumb, we present in this study the Ag-sputtering of semiconductors and metal films to avoid the lack of reproducibility attained by colloidal preparations on textiles. Films sputtered by the DC-magnetron sputtering (DC) and pulsed direct magnetron sputtering (DCP) were compared with films sputtered by highly ionized pulse plasma power magnetron sputtering (HIPIMS). The amounts of Ag needed to inactivate E. coli by HIPIMS were an order of magnitude lower than films loaded with DC. The more compact microstructure obtained by HIPIMS seems to lead to a significant saving of noble metal compared to the DC/DCP sputtering. The antibacterial kinetics evaluated for the Ag-sputtered films are estimated to be sufficient to decrease *
Sputtering of Cu 1-2 and TiO 2 /Cu 3-4 films on textile by conventional pulsed direct current mag... more Sputtering of Cu 1-2 and TiO 2 /Cu 3-4 films on textile by conventional pulsed direct current magnetron sputtering (DCP) and highly ionized pulsed plasma magnetron sputtering (HIPIMS) was performed to inactivate E. coli (Gram-negative) and methicillin resistant staphylococcus aureus (MRSA, Gram-positive). Low intensity sunlight with an intensity of 0.5-1% of solar irradiation AM1 were able to accelerate the bacterial inactivation. This is important when precluding the formation of biofilms pumping infectious bacteria in hospitals, schools and other public places since biofilms remain active for long-times and are a source of pathogens. Film surface characterization was carried out by X-ray fluorescence (XRF), profilometry, electron microscopy (HRTEM), AFM, contact angle CA and X-ray photoelectron spectroscopy (XPS). By highly ionized pulsed plasma magnetron sputtering (HIPIMS) inducing an increased M + -ions energy and high charge density of ~10 18-19 e-/m 3 , a coating ~38 nm thick inactivated E. coli within 10 minutes by way of a TiO 2 60/Cu 40 atomic percent target. By DCP sputtering the bacterial inactivation time was similar to the one induced by HIPIMS times but a coating ~ 600 nm thick was required.
A number of antibacterial films have been reported prepared by sol-gel technique leading to non-u... more A number of antibacterial films have been reported prepared by sol-gel technique leading to non-uniform, non-adhesive and showing short operational lifetime as antibacterial surfaces. This serious hindrance to the performance and stability retards the potential application of antibacterial films on a variety of surfaces in hospitals, schools and public places. This chapter presents the design, preparation, testing and evaluation of flexible thin films prepared by direct current and direct current pulsed magnetron sputtering (DC and DCP). We report in this chapter the highly ionized pulsed plasma magnetron sputtering (HIPIMS) deposition of Cu and Cu/TiO 2 thin films. These films show an accelerated antibacterial performance compared to thicker films deposited by DC/DCP sputtering leading to a saving in non-renewable heavy metals. Nanoparticules of Cu possess a high oxidative redox potentials leading to a fast bacterial loss of viability. In the case of Cu/TiO 2 films the abatement of Escherichia coli (from now on E. coli) and methicillin resistant Staphylococcus aureus (MRSA), the antibacterial kinetics is enhanced under visible light irradiation and was observed to occur within the minute range.
Ti was sputtered in a plasma chamber under a N 2 atmosphere, depositing TiN films on polyester fi... more Ti was sputtered in a plasma chamber under a N 2 atmosphere, depositing TiN films on polyester fibers. These films show a significant adsorption in the visible spectral region. A TiN layer 50 nm thick sputtered for 3 min under low intensity/actinic visible light led to the fastest bacterial inactivation (120 min). These innovative TiN nanoparticulate films were characterized by XPS, DRS and TEM.
ABSTRACT Fig. 1. (a) Spectral distribution of the Osram Lumilux 827/18 W lamp reported in the Osr... more ABSTRACT Fig. 1. (a) Spectral distribution of the Osram Lumilux 827/18 W lamp reported in the Osram catalogue (2001) and (b) spectral distribution of the Osram Lumilux 827/18 W lamp as provided May 2013 by Osram Winterthur, Switzerland.
This study presents the design, preparation, testing and characterization of TiN and TiN-Ag nanop... more This study presents the design, preparation, testing and characterization of TiN and TiN-Ag nanoparticulate films leading to photocatalytic and catalytic inactivation of Escherichia coli. When Ti was sputtered in N 2 atmosphere, the TiN films unexpectedly revealed semiconductor properties when irradiated under visible light due to the formation of TiO 2 showing absorption in the visible spectral region. In TiN-Ag films, Ag enhances the photocatalytic activity of TiN leading to faster bacterial inactivation. Evidence for the presence of TiO 2 and TiN in the films is presented by XPS. The TiN layers 50 nm thick sputtered by DC for 3 min led to complete inactivation of E. coli within 120 min. But TiN layers with a thickness >50 nm hinder the surface diffusion of charges reducing bacterial inactivation. The rate of TiN deposition was ∼1.4 × 10 15 atoms TiN/cm 2 s. For the TiN-polyester samples under visible light a 3 log 10 bacterial reduction (99.9%) was observed within 30 min while for TiN-Ag samples the same bacterial reduction was attained within ∼15 min. The absorption of the TiN-Ag samples in Kubelka-Munk (KM) units was directly proportional to the E. coli inactivation kinetics. TiN-Ag plasmon nanostructures are concurrently formed under low intensity visible light and accelerated bacterial inactivation. This study shows that TiN films have the potential to replace Ag-based disinfection materials leaching Ag into the environment.
Ag-TaN sputtered on polyester (PES) accelerated >6 times the bacterial inactivation kinetics comp... more Ag-TaN sputtered on polyester (PES) accelerated >6 times the bacterial inactivation kinetics compared to TaN-PES under actinic light irradiation. Direct current pulsed magnetron sputtering (DCP) was used to sputter Ag-TaN-PES and TaN-PES. Complete bacterial reduction by Ag-TaN occurred within 20 min compared to Ag-TiN (100 min) and Ag-ZrN (90 min). The co-sputtering of Ag and Ta on PES was carried out in an Ar/N 2 10% atmosphere. By ion-coupled plasma mass-spectrometry (ICP-MS) a reduced Ag-release was observed for Ag-TaN samples compared to Ag-PES samples within the disinfection period. The redox catalysis by the Ag-species during the bacterial disinfection was followed by X-ray photoelectron spectroscopy (XPS). A bacterial reduction mechanism is suggested consistent with the experimental findings. The nitride films were characterized by surface science methods.
In this study, the photoreactivation and the modification of dark repair of E. coli in a simulate... more In this study, the photoreactivation and the modification of dark repair of E. coli in a simulated secondary effluent were investigated after initial irradiation under different conditions. The simulated solar exposure of the secondary wastewater was followed by exposure to six different low-intensity fluorescent lamps (blacklight blue, actinic blacklight, blue, green, yellow and indoor light) for up to 8 h. When photoreactivation was monitored, blue and green colored fluorescent light led to increased bacterial regrowth. Blacklight lamps further inactivated the remaining bacteria, while yellow and indoor light led to accelerated growth of healthy cells. Exposure to fluorescent lamps was followed by long term storage in darkness, to monitor the bacterial repair in the dark. The response was correlated with the pre-exposure dose of applied solar irradiation, and to a lesser extent with the fluorescent light dose. Bacteria which had undergone extensive exposure showed no response under fluorescent light or during storage in the dark. Finally, the statistical treatment of the data allowed us to suggest a linear model, which is non-selective in terms of the fluorescent light applied. The estimation of the final bacterial population was predicted well (R-sq ∼ 75%) and the photoreactivation risk was found to be more important for cultivable cells.
Polyethylene-TiO 2 (from now on PE-TiO 2 ) transparent, non-scattering sputtered films have been ... more Polyethylene-TiO 2 (from now on PE-TiO 2 ) transparent, non-scattering sputtered films have been found effective in the discoloration of methylene blue (MB) under low intensity solar simulated light. By Fourier transform attenuated infrared spectroscopy (ATR-FTIR), the systematic shift and decrease in the s (CH 2 ) and s (C C) vibration-rotational bands was observed preceding MB discoloration. RF-pretreatment allowed a significant increase in the TiO 2 loading on PE compared to non-pretreated PE as shown by X-ray fluorescence (XRF). The PE-TiO 2 photo-switching from a hydrophobic to a hydrophilic surface was observed within 60 min under light while the reverse process was complete within 24 h in the dark. The position of the MB* and MB*/MB + levels allowing electron injecting into the TiO 2 cb is discussed. The probability for the MB T deactivation and of MB* reacting with O 2 leading to the short lived MB + cation is estimated. A mechanism for MB discoloration on PE-TiO 2 is suggested.
Antibacterial robust, uniform TiO 2 -ZrO 2 films on polyester (PES) under low intensity sunlight ... more Antibacterial robust, uniform TiO 2 -ZrO 2 films on polyester (PES) under low intensity sunlight irradiation made up by equal amounts of TiO 2 and ZrO 2 exhibited a much higher bacterial inactivation kinetics compared to pure TiO 2 or ZrO 2 .
This study addresses the preparation and characterization of hybrid films prepared from Titanium ... more This study addresses the preparation and characterization of hybrid films prepared from Titanium dioxide (TiO 2 ) Pickering stabilized acrylic polymeric dispersion as well as their bacterial inactivation efficiency under sunlight irradiation. Complete bacterial inactivation under low intensity simulated solar light irradiation (55 mW/cm 2 ) was observed within 240 min for the films containing 10 weight based on monomers (wbm) % of TiO 2 , whereas 360 min were needed for the films containing 20 wbm% of TiO 2. The hybrid films showed repetitive Escherichia coli (E. coli) inactivation under light irradiation. TiO 2 released from the films surfaces was measured by inductively coupled plasma mass spectrometry (IPC-MS), obtaining values of ∼0.5 and 1 ppb/cm 2 for the films containing 10 wbm% and 20 wbm% of TiO 2 , respectively, far below the allowed cytotoxicity level for TiO 2 (200 ppb). Transmission electron microscopy (TEM) of the hybrid films showed that TiO 2 nanoparticles (NPs) were located at the polymer particle's surface forming a continuous inorganic network inside the film matrix. Atomic force microscopy (AFM) images showed differences in the TiO 2 dispersion between the air-film and film-substrate interfaces. Films containing 10 wbm% of TiO 2 had higher roughness (Rg) at both interfaces than the one containing 20 wbm% of TiO 2 inducing an increase in the bacterial adhesion as well as the bacterial inactivation kinetics. The highly oxidative OH • -radicals participating in the bacterial inactivation were determined by fluorescence.
The kinetics of bacterial reduction of Staphylococcus aureus (MRSA) on co-sputtered TiO 2 /Cu-pol... more The 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.
Evidence is presented for radio-frequency plasma pretreatment enhancing the amount and adhesion o... more Evidence is presented for radio-frequency plasma pretreatment enhancing the amount and adhesion of TiO2 sputtered on polyester (PES) and on polyethylene (PE) films. Pretreatment is necessary to attain a suitable TiO2 loading leading to an acceptable Escherichia coli reduction kinetics in the dark or under light irradiation for PES-TiO2 and PE-TiO2 samples. The amount of TiO2 on the films was monitored by diffuse reflectance spectroscopy and X-ray fluorescence. X-ray electron spectroscopy shows the lack of accumulation of bacterial residues such as C, N and S during bacterial inactivation since they seem to be rapidly destroyed by TiO2 photocatalysis. Evidence was found for Ti(4+)/Ti(3+) redox catalysis occurring on PES-TiO2 and PE-TiO2 during the bacterial inactivation process. On PE-TiO2 surfaces, Fourier transform infrared spectroscopy (ATR-FTIR) provides evidence for a systematic shift of the na(CH2) stretching vibrations preceding bacterial inactivation within 60 min. The discon...
The bacteria inactivation of E. coli by Ag colloidal loaded cotton and polyester was investigated... more The bacteria inactivation of E. coli by Ag colloidal loaded cotton and polyester was investigated. Textile surfaces were pretreated by RF-plasma and UVC to introduce organic-polar groups containing oxygen functionalities binding/complexing/chelating Ag-clusters. Since sol-gel films are not mechanically stable, only exhibit low adhesion and can be wiped off by a cloth or thumb, we present in this study the Ag-sputtering of semiconductors and metal films to avoid the lack of reproducibility attained by colloidal preparations on textiles. Films sputtered by the DC-magnetron sputtering (DC) and pulsed direct magnetron sputtering (DCP) were compared with films sputtered by highly ionized pulse plasma power magnetron sputtering (HIPIMS). The amounts of Ag needed to inactivate E. coli by HIPIMS were an order of magnitude lower than films loaded with DC. The more compact microstructure obtained by HIPIMS seems to lead to a significant saving of noble metal compared to the DC/DCP sputtering. The antibacterial kinetics evaluated for the Ag-sputtered films are estimated to be sufficient to decrease *
Sputtering of Cu 1-2 and TiO 2 /Cu 3-4 films on textile by conventional pulsed direct current mag... more Sputtering of Cu 1-2 and TiO 2 /Cu 3-4 films on textile by conventional pulsed direct current magnetron sputtering (DCP) and highly ionized pulsed plasma magnetron sputtering (HIPIMS) was performed to inactivate E. coli (Gram-negative) and methicillin resistant staphylococcus aureus (MRSA, Gram-positive). Low intensity sunlight with an intensity of 0.5-1% of solar irradiation AM1 were able to accelerate the bacterial inactivation. This is important when precluding the formation of biofilms pumping infectious bacteria in hospitals, schools and other public places since biofilms remain active for long-times and are a source of pathogens. Film surface characterization was carried out by X-ray fluorescence (XRF), profilometry, electron microscopy (HRTEM), AFM, contact angle CA and X-ray photoelectron spectroscopy (XPS). By highly ionized pulsed plasma magnetron sputtering (HIPIMS) inducing an increased M + -ions energy and high charge density of ~10 18-19 e-/m 3 , a coating ~38 nm thick inactivated E. coli within 10 minutes by way of a TiO 2 60/Cu 40 atomic percent target. By DCP sputtering the bacterial inactivation time was similar to the one induced by HIPIMS times but a coating ~ 600 nm thick was required.
A number of antibacterial films have been reported prepared by sol-gel technique leading to non-u... more A number of antibacterial films have been reported prepared by sol-gel technique leading to non-uniform, non-adhesive and showing short operational lifetime as antibacterial surfaces. This serious hindrance to the performance and stability retards the potential application of antibacterial films on a variety of surfaces in hospitals, schools and public places. This chapter presents the design, preparation, testing and evaluation of flexible thin films prepared by direct current and direct current pulsed magnetron sputtering (DC and DCP). We report in this chapter the highly ionized pulsed plasma magnetron sputtering (HIPIMS) deposition of Cu and Cu/TiO 2 thin films. These films show an accelerated antibacterial performance compared to thicker films deposited by DC/DCP sputtering leading to a saving in non-renewable heavy metals. Nanoparticules of Cu possess a high oxidative redox potentials leading to a fast bacterial loss of viability. In the case of Cu/TiO 2 films the abatement of Escherichia coli (from now on E. coli) and methicillin resistant Staphylococcus aureus (MRSA), the antibacterial kinetics is enhanced under visible light irradiation and was observed to occur within the minute range.
Ti was sputtered in a plasma chamber under a N 2 atmosphere, depositing TiN films on polyester fi... more Ti was sputtered in a plasma chamber under a N 2 atmosphere, depositing TiN films on polyester fibers. These films show a significant adsorption in the visible spectral region. A TiN layer 50 nm thick sputtered for 3 min under low intensity/actinic visible light led to the fastest bacterial inactivation (120 min). These innovative TiN nanoparticulate films were characterized by XPS, DRS and TEM.
ABSTRACT Fig. 1. (a) Spectral distribution of the Osram Lumilux 827/18 W lamp reported in the Osr... more ABSTRACT Fig. 1. (a) Spectral distribution of the Osram Lumilux 827/18 W lamp reported in the Osram catalogue (2001) and (b) spectral distribution of the Osram Lumilux 827/18 W lamp as provided May 2013 by Osram Winterthur, Switzerland.
This study presents the design, preparation, testing and characterization of TiN and TiN-Ag nanop... more This study presents the design, preparation, testing and characterization of TiN and TiN-Ag nanoparticulate films leading to photocatalytic and catalytic inactivation of Escherichia coli. When Ti was sputtered in N 2 atmosphere, the TiN films unexpectedly revealed semiconductor properties when irradiated under visible light due to the formation of TiO 2 showing absorption in the visible spectral region. In TiN-Ag films, Ag enhances the photocatalytic activity of TiN leading to faster bacterial inactivation. Evidence for the presence of TiO 2 and TiN in the films is presented by XPS. The TiN layers 50 nm thick sputtered by DC for 3 min led to complete inactivation of E. coli within 120 min. But TiN layers with a thickness >50 nm hinder the surface diffusion of charges reducing bacterial inactivation. The rate of TiN deposition was ∼1.4 × 10 15 atoms TiN/cm 2 s. For the TiN-polyester samples under visible light a 3 log 10 bacterial reduction (99.9%) was observed within 30 min while for TiN-Ag samples the same bacterial reduction was attained within ∼15 min. The absorption of the TiN-Ag samples in Kubelka-Munk (KM) units was directly proportional to the E. coli inactivation kinetics. TiN-Ag plasmon nanostructures are concurrently formed under low intensity visible light and accelerated bacterial inactivation. This study shows that TiN films have the potential to replace Ag-based disinfection materials leaching Ag into the environment.
Ag-TaN sputtered on polyester (PES) accelerated >6 times the bacterial inactivation kinetics comp... more Ag-TaN sputtered on polyester (PES) accelerated >6 times the bacterial inactivation kinetics compared to TaN-PES under actinic light irradiation. Direct current pulsed magnetron sputtering (DCP) was used to sputter Ag-TaN-PES and TaN-PES. Complete bacterial reduction by Ag-TaN occurred within 20 min compared to Ag-TiN (100 min) and Ag-ZrN (90 min). The co-sputtering of Ag and Ta on PES was carried out in an Ar/N 2 10% atmosphere. By ion-coupled plasma mass-spectrometry (ICP-MS) a reduced Ag-release was observed for Ag-TaN samples compared to Ag-PES samples within the disinfection period. The redox catalysis by the Ag-species during the bacterial disinfection was followed by X-ray photoelectron spectroscopy (XPS). A bacterial reduction mechanism is suggested consistent with the experimental findings. The nitride films were characterized by surface science methods.
Uploads
Papers by sami RTIMI