Photocatalytic Antimicrobial Activity Research Articles

Dual-functional acridine-based coatings with anti-bacterial adhesion and durable photocatalytic antibacterial

Bacterial infections are a major public health challenge around the world. The development of novel surface coatings that effectively inhibit bacterial adhesion, proliferation and growth is a critical step in addressing this global challenge. Photocatalytic antibacterial therapy has proven to be an effective approach and has received increasing attention. However, it is still a challenge to obtain coatings with both antibacterial adhesion and durable photocatalytic antibacterial functions. Herein, an acridine-based coating with antibacterial adhesion and photocatalytic antibacterial properties was prepared by simple methods (i.e., spin-coating, spray-coating, and drop-coating) and can be applied to various substrates. The bacterial anti-adhesion test results showed that the coating could effectively prevents the adhesion of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa), indicating the strong anti-fouling capability. The acridine-based coating demonstrated durable photocatalytic antimicrobial activity, remaining 99.3 % antibacterial effective against all three bacterial strains even after 30 days exposed to visible light. The coating can significantly reduce or eliminate the risk of contamination and cross-contamination, making it ideal for use in public healthcare environments.

Chitosan synergizes with bismuth-based metal-organic frameworks to construct double S-type heterojunctions for enhancing photocatalytic antimicrobial activity

In recent years, photocatalytic technology has been introduced to develop a new kind antimicrobial agents fighting antibiotic abusing and related drug resistance. The efforts have focused on non-precious metal photocatalysts along with green additives. In the present work, a novel bis-S heterojunctions based on the coupling of polysaccharide (CS) and bismuth-based MOF (CAU-17) s synthesized through a two-step method involving amidation reaction under mild conditions. The as prepared photocatalyst literally extended the light response to the near-infrared region. Owing to its double S-type heterostructure, the lifetime of the photocarriers is significantly prolonged and the redox capacity are enhanced. As a result, the as prepared photocatalyst indicated inhibition up to 99.9 % under 20 min of light exposure against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria as well as drug-resistant bacteria (MRSA). The outstanding photocatalytic performance is attributed to the effective charge separation and migration due to the unique double S heterostructure. Such a double S heterostructure was confirmed through transient photocurrent response, electrochemical impedance spectroscopy tests and electron spin resonance measurements. The present work provides a basis for the simple synthesis of high-performance heterojunction photocatalytic inhibitors, which extends the application of CAU-17 in environmental disinfection and wastewater purification.

Antimicrobial Activity of Biogenic Metal Oxide Nanoparticles and Their Synergistic Effect on Clinical Pathogens.

The rising prevalence of antibiotic-resistance is currently a grave issue; hence, novel antimicrobial agents are being explored and developed to address infections resulting from multiple drug-resistant pathogens. Biogenic CuO, ZnO, and WO3 nanoparticles can be considered as such agents. Clinical isolates of E. coli, S. aureus, methicillin-resistant S. aureus (MRSA), and Candida albicans from oral and vaginal samples were treated with single and combination metal nanoparticles incubated under dark and light conditions to understand the synergistic effect of the nanoparticles and their photocatalytic antimicrobial activity. Biogenic CuO and ZnO nanoparticles exhibited significant antimicrobial effects under dark incubation which did not alter on photoactivation. However, photoactivated WO3 nanoparticles significantly reduced the number of viable cells by 75% for all the test organisms, thus proving to be a promising antimicrobial agent. Combinations of CuO, ZnO, and WO3 nanoparticles demonstrated synergistic action as a significant increase in their antimicrobial property (>90%) was observed compared to the action of single elemental nanoparticles. The mechanism of the antimicrobial action of metal nanoparticles both in combination and in isolation was assessed with respect to lipid peroxidation due to ROS (reactive oxygen species) generation by measuring malondialdehyde (MDA) production, and the damage to cell integrity using live/dead staining and quantitating with the use of flow cytometry and fluorescence microscopy.

Fabrication of g-C3N4 nanosheets immobilized Bi2S3/Ag2WO4 nanorods for photocatalytic disinfection of Staphylococcus aureus cells in wastewater: Dual S-scheme charge separation pathway

In this work, graphitic carbon nitride (g-C3N4) immobilized Bi2S3/Ag2WO4 (BS/AW/CN) heterojunction was successfully fabricated using a facile multi-step approach. The fabricated nanomaterials were characterized using different sophisticated technologies. The morphological investigations revealed the existence of g-C3N4 nanosheets loaded with Ag2WO4 and Bi2S3 in a nanorod-like structure. The BS/AW/CN nanocomposite exhibited improved surface area, which was attributed to the regular deposition of Bi2S3/Ag2WO4 on the surface of g-C3N4 nanosheets. The obtained BS/AW/CN heterojunction displayed excellent light absorption ability with promoted photoelectrochemical properties, which was attributed to the lower band gap energy of Bi2S3 species. The BS/AW/CN (0.25 g/L) showed superior photocatalytic antimicrobial activity against Staphylococcus aureus cells (∼1 × 107 CFU/mL) under 140 W of visible-light illumination, where complete inactivation activity was observed in 90 min. The disinfection kinetics verified the faster photoreaction process over BS/AW/CN compared with single and binary catalysts. The inactivated bacterial cells were further elucidated by fluorescence spectroscopy and electron microscopy techniques. The photocatalytic disinfection activity was also investigated under different operating conditions like pH, catalyst loading, and bacterial density. The stability studies verified the high photostability of the obtained heterojunction in five photoreaction runs, suggesting its potential applicability in wastewater disinfection systems. The electronic characteristics and radical trapping results were considered in justifying the dual-S-scheme heterojunction mechanism in the presence of BS/AW/CN. In conclusion, this work demonstrates the feasibility of an efficient visible-light responsive photocatalyst for Staphylococcus aureus cells disinfection in wastewater treatment systems.

Facile conglomeration of guar gum/TiO2/Fe3O4 composite materials for photocatalytic antimicrobial activities

In present communication we report the guar gum based composite materials, prepared by incorporating TiO2 and Fe3O4 by sol-gel method. The composites were synthesized by hydrolysis and dehydroxylation polymerization of a Titanium (IV) butoxide and mixed oxides of iron (Fe3O4) by the sol-gel method within the guar gum matrix using hydrochloric acid as an acid catalyst. The synthesized materials were calcined in an electrical muffle furnace at 200 °C, 400 °C and 600 °C, and characterized by FTIR, XRD and TGA. Thermal properties of the composites were improved as evidenced from the Thermo Gravimetric Analysis (TGA) data. A strong photocatalytic antimicrobial activity of about 90% was exhibited by composite material calcined at 600 °C against gram-positive (Staphylococcus aureus) bacteria, and therefore, the material could be considered as an important raw material for developing an active food packaging.

Super-hydrophobic and photocatalytic antimicrobial activity of iodine-doped ZnO nanoarray films

Iodine(i) doped ZnO nanoarray films (ZnO/I-X) were prepared on a silicon wafer by the in itu growth method.

Study of the Photocatalytic Antimicrobial Activity of Nanocomposites Based on TiO2–Al2O3 under Action of LED Radiation (405 nm) on Staphylococci

Study of the Photocatalytic Antimicrobial Activity of Nanocomposites Based on TiO2–Al2O3 under Action of LED Radiation (405 nm) on Staphylococci

Multiscale Metal Oxide Particles to Enhance Photocatalytic Antimicrobial Activity against Escherichia coli and M13 Bacteriophage under Dual Ultraviolet Irradiation.

Antimicrobial activity of multiscale metal oxide (MO) particles against Escherichia coli (E. coli) and M13 bacteriophage (phage) was investigated under dual ultraviolet (UV) irradiation. Zinc oxide (ZnO), magnesium oxide (MgO), cuprous oxide (Cu2O), and cupric oxide (CuO) were selected as photocatalytic antimicrobials in MO particles. Physicochemical properties including morphology, particle size/particle size distribution, atomic composition, crystallinity, and porosity were evaluated. Under UV-A and UV-C irradiation with differential UV-C intensities, the antimicrobial activity of MO particles was monitored in E. coli and phage. MO particles had nano-, micro- and nano- to microscale sizes with irregular shapes, composed of atoms as ratios of chemical formulae and presented crystallinity as pure materials. They had wide-range specific surface area levels of 0.40–46.34 m2/g. MO particles themselves showed antibacterial activity against E. coli, which was the highest among the ZnO particles. However, no viral inactivation by MO particles occurred in phage. Under dual UV irradiation, multiscale ZnO and CuO particles had superior antimicrobial activities against E. coli and phage, as mixtures of nano- and microparticles for enhanced photocatalytic antimicrobials. The results showed that the dual UV-multiscale MO particle hybrids exhibit enhanced antibiotic potentials. It can also be applied as a next-generation antibiotic tool in industrial and clinical fields.

Long-term and stable antimicrobial properties of immobilized Ni/TiO2 nanocomposites against Escherichia coli, Legionella thermalis, and MS2 bacteriophage

Nickel has been extensively used as a high work function metal because of its abundance, low cost, relatively non-toxic nature, and environmentally benign characteristics. However, it has rarely been extended in a form of immobilized composite, which is a practical strategy applicable for photocatalytic antimicrobial activities. In this study, a composite of nickel and TiO2 (Ni/TiO2) was prepared using a photodeposition method, and its antibacterial properties were investigated using Escherichia coli (E. coli). To optimize Ni/TiO2 synthesis, the effect of various photodeposition conditions on antibacterial performance were investigated, such as the light irradiation time, metal content, TiO2 crystalline structure, and presence or absence of electron donors (i.e., methanol). The optimized 2 wt% Ni/TiO2 exhibited an antibacterial efficiency of 3.74 log within 7 min, which is more than 10-fold higher than that of pristine TiO2 (2.54 log). Based on this optimized weight ratio, Ni/TiO2 was immobilized on a steel mesh using an electrospray/thermal compression method, and its antibacterial performance was further assessed against E. coli, MS2 bacteriophage virus (MS2 phage), and a common pulmonary pathogen (Legionella thermalis, L. thermalis). Within 70 min, all target microorganisms achieved an inactivation that exceeded 4 log. Furthermore, the long-term stability and sustainable usability of the Ni/TiO2 mesh were confirmed by performing more than 50 antibacterial evaluation cycles using E. coli. The results of this study facilitate the successful utilization of immobilized Ni/TiO2 mesh in water disinfection applications.

Evaluation of B-ZnO on photocatalytic inactivation of Escherichia coli and Enterococcus sp

In this study the photocatalytic inactivation of Escherichia coli (E. coli) and Enterococcus sp. wild strains was carried out using as photocatalyst boron-doped ZnO (B-ZnO). The photocatalytic performance of this material was compared with two commercial catalysts: ZnO and TiO2. Furthermore, the control processes of solar disinfection (SODIS) and stirring were evaluated. The performance of the catalysts was evaluated under darkness and solar simulated irradiation. Logarithmic units of inactivation and concentration of Zn2+ release during the experiments were determined. The photocatalytic inactivation of the strains was adjusted to a log-linear shoulder or tail kinetic model. To maximize the kinetic constant and determine the catalyst with the best photocatalytic performance, a desirability function was applied. Under darkness, stirring and TiO2 in suspension did no present effect in the population of both bacteria. A reduction of 1-log unit of E. coli was observed in the processes with ZnO and B-ZnO on darkness. However, Enterococcus sp. only was inactivated in darkness using B-ZnO, reaching 1.5-log. The increase of the antimicrobial effect of B-ZnO was attributed to Zn2+ release and the formation of acid sites promoted by B3+ ions in the B-ZnO catalyst. Under solar simulated irradiation, E. coli and Enterococcus sp. reached 6-log and 3-log respectively during 180 min of exposure without catalyst. The photocatalytic inactivation of E. coli was negligible using TiO2 catalyst, while heterogeneous photocatalysis using ZnO and B-ZnO materials reached 6-log during 30 min and 60 min of lighting, respectively. The photocatalytic inactivation of E. coli using ZnO exhibited higher kinetic constant value (1.12 min−1) compared to that obtained with doped B-ZnO (0.23 min−1). In the case of the photocatalytic inactivation of Enterococcus sp., 3-log in 180 min was reached using B-ZnO (0.22 min−1) while 1-log was attained using ZnO (0.02 min−1) and TiO2 (0.04 min−1). From desirability function, the maximization of the kinetic constants of inactivation of E. coli and Enterococcus sp. allowed selecting the B-ZnO as the best material due to its enhanced photocatalytic antimicrobial activity against both strains.

Effect of chalcogens (S, Se, and Te) on the anatase phase stability and photocatalytic antimicrobial activity of TiO2

The effect of chalcogens such as sulphur (S), selenium (Se), and tellurium (Te) on the anatase to rutile phase transition (ART) of titanium dioxide (TiO2) was investigated. 2 mol % of chalcogen doped TiO2 was synthesised via a sol–gel technique. The as-synthesised samples were calcined at different temperatures from 500 °C to 800 °C for 2 h. X-ray diffraction (XRD) and Raman spectroscopy were used to study the ART of TiO2. Te -TiO2 showed the highest anatase phase (44%) at 750 °C as compared to other samples. X-ray photoelectron spectroscopy (XPS) and UV–visible diffuse reflectance spectroscopy (UV-DRS) was further utilised to investigate the oxidation state and optical properties. UV-DRS results showed that the substitutional doping of chalcogens in the TiO2 lattice enhanced visible light absorption. The photocatalytic efficiency was tested for the disinfection of Escherichia coli (E.coli) under visible light irradiation. It is noted that while the chalcogen modified TiO2 improved the anatase stability the antimicrobial activity is not significantly enhanced compared to pure anatase TiO2 under visible light illumination. Te-TiO2 attained 100% disinfection within 70 min of visible light irradiation and maintained equal antibacterial efficiency as pure TiO2 at 750 °C.

Bacterial Disinfection Using Polymer Based Hybrids

Sol-gel chemistry was adeptly exploited to fabricate polymer based hybrids for solar disinfection to render clean drinking water. The present research study was carried out by inclusion of different proportions of titania (2.5 and 7.5 wt %) that covalently cross-linked with the polymer matrix. In addition to morphological studies, the optical band gap and wavelength absorbed was investigated through UV-Vis absorption spectra. Moreover, the efficacy of photocatalytic antimicrobial activity of polymer based hybrids was evaluated using source water with controlled amount of total coliform that causes waterborne diseases. This research provided a green synthesis approach for water disinfection along with no disinfection byproduct formation, thus, rendering energy efficient and cost-effective water disinfection.

Antimicrobial activity of printed composite TiO2/SiO2 and TiO2/SiO2/Au thin films under UVA-LED and natural solar radiation

Composite TiO2/SiO2 porous coatings modified with bipyramid-like gold nanoparticles were prepared by means of sol-gel and inkjet printing technique, comprehensively characterized and studied for photocatalytic disinfection of drinking water with fecal contamination by natural bacteria consortia. Photocatalytic antimicrobial activity of prepared thin films was evaluated against gram-negative (Escherichia coli and Total coliforms) and gram-positive bacteria (Enterococci). Elimination rate of all tested bacteria increased when photocatalytic coatings were used in comparison with solar disinfection. The best results in terms of antimicrobial activity were obtained with TiO2/SiO2/Au thin films under natural solar radiation, which demonstrated the highest antimicrobial activity, enhancing the inactivation rates of E. coli, Total coliforms and Enterococci 1.5, 1.3 and 1.6 times, respectively as compared to solar disinfection without photocatalyst. Remarkable difference in bacteria sensitivity for photocatalytic disinfection was observed with trend E. coli > Total coliforms > Enterococci. No release of gold and titanium was detected during photocatalytic water disinfection test. Regrowth of E. coli, Total coliforms and Enterococci after photocatalytic bacteria inactivation under UVA-LED and natural solar radiation was lower than 1% (24, 48 and 72 h), indicating potential application of prepared coatings for production of safe drinking water.

Effect of calcination temperature on the microstructure and antimicrobial activity of boron and cerium co-doped titania nanomaterials

The photocatalytic antimicrobial activities of B and Ce co-doped TiO2 nanomaterials calcinated at different temperatures under visible-light illumination were investigated. B/Ce–TiO2 nanomaterials were characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectrum (DRS) Photocatalytic antimicrobial activities of the nanomaterials were determined by the inhibition zone and shaking-flask method against Escherichia coli and Staphylococcus aureus. Results show that the phase of B/Ce–TiO2 could be transformed from amorphous to anatase and then to rutile by increasing the calcination temperature. At lower calcination temperature, B/Ce–TiO2 nanomaterials exhibit smaller crystal size and higher specific surface area. The present forms of B ions were a substitution B occupying O sites, interstitial B atoms and B–O–B bonds. Ce3+ and Ce4+ co-existed in the materials. Results of the antimicrobial experiment under visible-light irradiation show that B/Ce–TiO2 nanomaterials exhibited enhanced antimicrobial activities. Ultimately, the action mechanism of B/Ce–TiO2 was discussed.

Synthesis and characterization of chitosan-TiO2:Cu nanocomposite and their enhanced antimicrobial activity with visible light

In the present investigation, novel strategy for the preparation of hybrid nanocomposite containing organic polymer (Chitosan) and inorganic (TiO2:Cu) nanoparticles (NPs) has been developed and demonstrated its biomedical application. The sol–gel and ultra-sonication method assisted for the preparation of uniformly distributed Chitosan-TiO2:Cu (CS-CT) nanocomposite. The structural properties of prepared CS-CT nanocomposite were studied by XRD and FTIR techniques. The XPS was used to estimate elemental composition of the nanocomposite. Thermal properties were studied using TGA. TEM and SEM analysis showed the non-spherical nature of NPs with the average mean diameter 16nm. The optical properties were analyzed with UV–vis diffuse reflectance spectroscopy to confirm optical absorption in the visible region of light. Where CS-CT showed 200% enhanced light mediated photocatalytic antimicrobial activity against microorganism (Escherichia coli and Staphylococcus aureus) as compared with control. The antimicrobial activity of CS-CT nanocomposite in presence of light is found to be enhanced than that of its components, this is due to synergistic effect of organic and inorganic material complimenting each other’s activity. The OH radicals release studied by PL spectroscopy on the surface of nanocomposite was used to examine antibacterial activity. Cytotoxicity assessment of CS-CT on human fibroblast cells was performed by MTT assay.

Doping TiO2 with boron or/and cerium elements: Effects on photocatalytic antimicrobial activity

The aim of this study is to study the effect of ions co-doped on the photocatalytic antimicrobial activities of TiO2 nano-materials under illumination with visible light. Pure TiO2, boron or cerium single doped TiO2, boron and cerium co-doped TiO2 nano-materials were synthesized by a sol–gel method calcinated at 600 °C and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis absorption spectra (DRS) and Photoluminescence spectra (PL). The photocatalytic antimicrobial activities of nano-materials were determined by killing rate of Staphylococcus aureus. The results show TiO2, B or/and Ce doped TiO2 nano-materials are anatase phase as the main crystalline phase. TiO2 doped with ions exhibit small crystal size and high specific surface area. B and Ce co-doping decreases the band gap of the TiO2 and effectively inhibits electrons and holes recombination. The present forms of boron ions are a substitution B occupying O sites, interstitial boron atoms and BOB bonds in [BO3]; Ce3+ and Ce4+ co-exist in the materials. The antimicrobial results show killing rate of B and Ce co-doping TiO2 is superior to the other materials, and B and Ce co-doped has a synergistic antimicrobial effect.

Photocatalytic Effects of Acrylic Resins Incorporated with Nano-titanium Dioxide on Planktonic and Biofilm Growth of Four Cariogenic Bacteria

Aims: The activities of cariogenic bacteria in biofilm on acrylic baseplates of removable orthodontic appliances and partial denture contribute to dental caries, inflammation of gingiva and periodontal disease. This in vitro study evaluates the Original Research Article Annual Research & Review in Biology, 4(17): 2695-2708, 2014 2696 photocatalytic antimicrobial activity of acrylic specimens (AS) containing NanoTiO2 under ultraviolet type A (UVA) illumination against four cariogenic bacteria. Study Design: An in vitro study Place and Duration of Study: Department of Microbiology and Department of Orthodontics, Tehran University of Medical Sciences (TUMS); Department of Chemistry, Tarbiat Modares University, between June 2011 and March 2012. Methodology: Chemical-cure acrylic resins, Polymethylmethacrylates (PMMAs), were used to synthesize acrylic specimens containing NanoTiO2 (NanoT-AS). Antibacterial activity of NanoT-AS were assessed against Streptococcus sobrinus, Streptococcus mutans, Lactobacillus acidophilus as well as Lactobacillus casei and co-cultures of the four species by adherence inhibition as well as planktonic and biofilm bacterial cells growth inhibition on NanoT-AS under UVA illumination (NanoTiO2+/UVA+). Results: Exposure to NanoTiO2+/UVA+ reduced bacterial adherence by 43.8-96.5% depending on the microorganism type. NanoTiO2+/UVA+ showed 1.7-6.0 log decrease planktonic cultures in time-dependent manner over a 4h period (P<0.05). NanoT-AS inhibited significantly biofilm formation of all test bacteria and co-cultures by 44.2-93.1%, compared to unmodified PMMA (control) under UVA illumination. Some inhibitory activity of NanoTiO2+/UVA+ could be maintained even after the third generation of biofilm growth. Conclusion: The data presented here are novel in that they prove that NanoTiO2+/UVA+ effectively inhibited adherence of cariogenic bacteria to NanoT-AS surfaces as well as strong antimicrobial activity in the planktonic phase and subsequent biofilm formation. This data shows NanoTiO2+/UVA+ has the potential to minimize cariogenic microorganism’s adherence and colonization on acrylic specimens and this novel acrylic resin formulation could be developed as a denture and orthodontic appliances base.

Photocatalytic antimicrobial effect of TiO2 anatase thin-film–coated orthodontic arch wires on 3 oral pathogens

The aim of this study was to introduce antimicrobial activity to stainless steel orthodontic arch wires by coating them with TiO_2 in anatase form. Stainless steel (0.016 × 0.022 inch), D-rect (0.016 × 0.022 inch), and multistranded hammered retainer wires (0.014 × 0.018 inch) were coated with TiO_2 anatase by the sol-gel dip coating method. The wires were assessed for their photocatalytic antimicrobial activity against Streptococcus mutans, Candida albicans, and Enterococcus faecalis. After illumination under UVA (315-400 nm) at 1.0 mW/cm^2 for 1 h, the reduction efficiencies of the anatase-coated arch wires were calculated by using colony-forming unit counts. All anatase-coated arch wires showed remarkable inhibitor effects against the test microorganisms under UVA. The most efficient wire on S. mutans was the stainless steel wire, with a 99.99% reduction in growth, but multistranded hammered retainer wire was the most active against both C. albicans and E. faecalis, with 98.0% and 91.68% reduction rates, respectively. TiO_{2}-coated arch wires exposed to UVA illumination showed significant antimicrobial activity when compared with uncoated samples and coated, but not UVA-exposed, samples. Our results suggest that the antimicrobial effect of TiO_{2}-coated arch wires in long-lasting orthodontic treatments would be beneficial for the prophylaxis of caries.

Antimicrobial activity of titania/silver and titania/copper films prepared by CVD

We have previously reported the production of photocatalytically active films of TiO 2/Ag and TiO 2/CuO grown by atmospheric pressure thermal CVD that had high antimicrobial activity. The present study compares the activity of dual layers and co-deposited TiO 2–CuO with single layers. We also compared the BS ISO 27447:2009 method with our previously reported method for determining photocatalytic antimicrobial activity and showed that although the activity was reduced in the BS method, probably due to the lower UV irradiation used, there was still a good antimicrobial activity. The results showed that Ag–TiO 2 surfaces retained photocatalytic self-cleaning activity measured by stearic acid oxidation whereas Cu–TiO 2, both layered and co-deposited had very low activity. However, both were antimicrobial against Escherichia coli with activity of the Cu–TiO 2 films greatly enhanced by irradiation possibly via a photo-Fenton type reaction. The activity of the Ag–TiO 2 films against Pseudomonas aeruginosa and MRSA (methicillin resistant Staphylococcus aureus) showed reduced killing activity with an environmental isolate of P. aeruginosa and the MRSA showing only 3 log and 1.5 log reductions respectively. The implications for their use for reduction of surface contamination by microorganisms as part of control measures for healthcare associated infections are discussed.

Photocatalytic antimicrobial activity of thin surface films of TiO2, CuO and TiO2/CuO dual layers on Escherichia coli and bacteriophage T4

TiO(2)-coated surfaces are increasingly studied for their ability to inactivate microorganisms. The activity of glass coated with thin films of TiO(2), CuO and hybrid CuO/TiO(2) prepared by atmospheric Chemical Vapour Deposition (Ap-CVD) and TiO(2) prepared by a sol-gel process was investigated using the inactivation of bacteriophage T4 as a model for inactivation of viruses. The chemical oxidising activity was also determined by measuring stearic acid oxidation. The results showed that the rate of inactivation of bacteriophage T4 increased with increasing chemical oxidising activity with the maximum rate obtained on highly active sol-gel preparations. However, these were delicate and easily damaged unlike the Ap-CVD coatings. Inactivation rates were highest on CuO and CuO/TiO(2) which had the lowest chemical oxidising activities. The inactivation of T4 was higher than that of Escherichia coli on low activity surfaces. The combination of photocatalysis and toxicity of copper acted synergistically to inactivate bacteriophage T4 and retained some self-cleaning activity. The presence of phosphate ions slowed inactivation but NaCl had no effect. The results show that TiO(2)/CuO coated surfaces are highly antiviral and may have applications in the food and healthcare industries.