Effect of Titanium Dioxide Film Thickness on Photocatalytic and Bactericidal Activities AgainstListeria monocytogenes (original) (raw)
Related papers
Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, 2015
Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and covered with a thin film of nanocrystalline titanium dioxide by dip coating. The films were then photosensitized by titanium(iv) surface charge transfer complexes formed by impregnation with catechol. The photoactivity of the coatings up to 460 nm was confirmed by photoelectrochemical measurements. The photoinactivation of Escherichia coli and Staphylococcus aureus was evaluated by a glass adhesion test based on ISO 27447:2009(E) in the presence of visible light. The coating showed good antimicrobial activity induced by light from a light-emitting diode (405 nm), in particular towards E. coli ATCC 25922 strain. Adaptation of ISO 27447:2009(E) to assess bacterial photoinactivation by photocatalytic coatings will allow this procedure to be applied for the comparison of photoactivity under a range of irradiation conditions.
Biofilms, containing pathogenic bacteria, represent a recurrent economic and safety problem in food industries, due to their high resistance to cleaning and sanitizing procedures. The development of photoactive surfaces with bactericidal property could facilitate the elimination of such microbial biofilms. One solution may be to deposit a photocatalyst top-layer (TiO 2) on conventional materials used in food plants. Our aim is to study the photocatalytic activity of such layers on the adhesion and viability of different bacteria present on food plants, especially in pork meat factory: Listeria monocytogenes, Yersinia enterocolitica and Pseudomonas fragi. Glass substrates were coated with TiO 2 thin films by radio-frequency magnetron sputtering under various deposition conditions (deposition temperature T, oxygen partial pressure P O2). The characterization of the TiO 2 thin layers was performed using spectrophotometry, scanning electron microscopy and X-ray diffraction analysis. And photocatalytic activity under UVA illumination (365 nm) has been checked for all samples. Bactericidal activity has been demonstrated on the bacteria tested by enumeration of the adherent cells and in situ fluorescent labeling after three hours of contact with the thin film and a subsequent UVA illumination. Adherent bacteria with damaged bacterial cell wall were observed using a scanning electron microscopy; this can be associated with presence of oxidative stress due to the photocatalytic activity of the TiO 2 thin layer. The selected TiO 2 coating presents a photocatalytic activity leading to an oxidative stress. This activity provides bactericidal properties against different strains from the meat industry. This thin layer could be optimized by modifying anionic composition (band-gap reduction) during coating in order to be active under solar light so it could be used to fight against biofilms.
Photobactericidal effects of TiO2 thin films at low temperatures—A preliminary study
Journal of Photochemistry and Photobiology A: Chemistry, 2010
The efficacy of TiO 2 photocatalysis for the destruction of pathogenic bacteria has been demonstrated by a number of groups over the past two decades. Pathogenic bacteria represent a significant hazard for the food and drink industry. Current practices in this industry dictate that rigorous sanitizing regimes must be regularly implemented resulting in lost production time. The incorporation of a TiO 2 antibacterial surface coating in this setting would be highly desirable. In this paper we report a preliminary study of the efficacy of a TiO 2 coating, doped with the lanthanide, neodymium, at low temperature conditions such as those utilised in the food and drink sector. The rapid destruction of Staphylococcus aureus, a common foodborne pathogen, was observed using TiO 2 films coated to glass and steel substrates.
Applied and Environmental Microbiology, 2006
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Coatings, 2014
In damp environments, indoor building materials are among the main proliferation substrates for microorganisms. Photocatalytic coatings, including nanoparticles of TiO 2 , could be a way to prevent microbial proliferation or, at least, to significantly reduce the amount of microorganisms that grow on indoor building materials. Previous works involving TiO 2 have already shown the inactivation of bacteria by the photocatalysis process. This paper studies the inactivation of Escherichia coli bacteria by photocatalysis involving TiO 2 nanoparticles alone or in transparent coatings (varnishes) and investigates different parameters that significantly influence the antibacterial activity. The antibacterial activity of TiO 2 was evaluated through two types of experiments under UV irradiation: (I) in slurry with physiological water (stirred suspension); and (II) in a drop deposited on a glass plate. The results confirmed the difference in antibacterial activity between simple drop-deposited inoculum and inoculum spread under a plastic film, which increased the probability of contact between TiO 2 and bacteria (forced contact). In addition, the major effect of the nature of the suspension on the photocatalytic disinfection ability was highlighted. Experiments were also carried out at the surface of transparent coatings formulated using nanoparticles of TiO 2 . The results showed significant antibacterial activities after 2 h and 4 h and suggested that improving the formulation would increase efficiency.
FEMS Microbiology Letters, 2021
Antimicrobial materials are tools used to reduce the transmission of infectious microorganisms. Photo-illuminated titania (TiO2) is a known antimicrobial material. Used as a coating on door handles and similar surfaces, it may reduce viability and colonization by pathogens and limit their spread. We tested the survival of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Saccharomyces cerevisiae on a nano-structured TiO2-based thin film, called ‘NsARC’, and on stainless steel under a variety of light wavelengths and intensities. There was significantly less survival (P <0.001) of all the organisms tested on NsARC compared to inert uncoated stainless steel under all conditions. NsARC was active in the dark and possible mechanisms for this are suggested. NsARC inhibited biofilm formation as confirmed by scanning electron microscopy. These results suggest that NsARC can be used as a self-cleaning and self-sterilizing antimicrobial surface coating for the prevention...
Processes
The antibacterial photocatalytic activity of TiO2 supported over two types of substrates, borosilicate glass tubes (TiO2/SiO2-borosilicate glass tubes (BGT)) and low-density polyethylene pellets (TiO2-LDPE pellets), which were placed in a compound parabolic collectors (CPC) reactor, was evaluated against Enterobacter cloacae and Escherichia coli under sunlight. Three solar photocatalytic systems were assessed, suspended TiO2, TiO2/SiO2-BGT and TiO2-LDPE pellets, at three initial bacterial concentrations, 1 × 105; 1 × 103; 1 × 101 CFU/mL of E. coli and total bacteria (E. cloacae and E. coli). The solar photo-inactivation of E. coli was achieved after two hours with 7.2 kJ/L of UV-A, while total bacteria required four hours and 16.5 kJ/L of UV-A. Inactivation order of E. coli was determined, as follows, suspended TiO2/sunlight (50 mg/L)…