Antibiofilm effect of mesoporous titania coatings on Pseudomonas aeruginosa biofilms

Journal Pre-proof Antibiofilm effect of mesoporous Pseudomonas aeruginosa biofilms

titania

coatings

on

Magdalena Pezzoni, Paolo N. Catalano, Diana C. Delgado, Ramón Pizarro, Martín G. Bellino, Cristina S. Costa PII:

S1011-1344(18)31351-4

DOI:

https://doi.org/10.1016/j.jphotobiol.2019.111762

Reference:

JPB 111762

To appear in:

Journal of Photochemistry & Photobiology, B: Biology

Received date:

26 November 2018

Revised date:

12 June 2019

Accepted date:

22 December 2019

Please cite this article as: M. Pezzoni, P.N. Catalano, D.C. Delgado, et al., Antibiofilm effect of mesoporous titania coatings on Pseudomonas aeruginosa biofilms, Journal of Photochemistry & Photobiology, B: Biology(2019), https://doi.org/10.1016/ j.jphotobiol.2019.111762

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© 2019 Published by Elsevier.

Journal Pre-proof

Antibiofilm effect of mesoporous titania coatings on Pseudomonas aeruginosa biofilms

Magdalena Pezzonia, Paolo N. Catalanob, Diana C. Delgadob, Ramón Pizarroa, Martín G. Bellinob and Cristina S. Costaa*

Departamento de Radiobiología, Comisión Nacional de Energía Atómica, Av. General

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a.

Departamento de Micro y Nanotecnología, Instituto de Nanociencia y

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b

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Paz 1499, B1650KNA San Martín, Argentina.

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1499, B1650KNA San Martín, Argentina.

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Nanotecnología-Comisión Nacional de Energía Atómica-CONICET, Av. General Paz

E-mail addresses:

[email protected]

Paolo N. Catalano

[email protected]

Diana C. Delgado

[email protected]

Ramón Pizarro

[email protected]

Martín G. Bellino

[email protected]

Cristina S. Costa

[email protected]

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Magdalena Pezzoni

*Corresponding author Address: Comisión Nacional de Energía Atómica, Departamento de Radiobiología, Avda. General Paz 1499, B1650KNA General San Martín, Buenos Aires, Argentina. Tel.: +54 11 6772 7011; fax +54 11 6772 7188. E-mail address: [email protected]

Journal Pre-proof Abbreviations Ultraviolet-A radiation (320-400 nm)

TiO2

Titania, Titanium dioxide

ROS

Reactive Oxygen Species

EISA

Evaporation-Induced Self Assembly

GIXD

Grazing Incidence X-ray Diffraction

SEM

Scanning Electron Microscopy

NM

Non-Mesoporous films

MB

Mesoporous films obtained with Brij-58

MF

Mesoporous films obtained with Pluronics-F127 Colony Forming Units

OD650

Optical Density at 650 nm

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CFU

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UVA

Journal Pre-proof ABSTRACT Activation of photocatalytic titania by ultraviolet-A (UVA) radiation has been proposed as a good approach for combating bacteria. Titania powder, in solution or immobilized on a surface, has excellent UVA-assisted killing properties on several microorganisms. However, these properties could not be demonstrated in biofilms of Pseudomonas aeruginosa, a resistant opportunistic human pathogen that can cause severe complications in patients who are immunocompromised or have burn wounds or cystic

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fibrosis. P. aeruginosa biofilms have detrimental effects on health and industry, causing

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serious economic damage. In this study, the effect of titania photocatalysis for

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controlling P. aeruginosa biofilms was investigated by employing different coatings obtained through sol-gel and evaporation-induced self-assembly. Biofilms were grown

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on non-mesoporous and mesoporous titania surfaces with different pore sizes, which

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were achieved based on the use of surfactants Brij-58 and Pluronics-F127. In addition, two structural forms of titania were assayed: amorphous and anatase. As well as

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inhibiting biofilm formation, these coatings significantly enhanced the bactericidal effect

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of UVA on P. aeruginosa biofilms. The most efficient surface with regard to total antibacterial effect was the mesoporous Brij-58-templated anatase film, which,

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compared to control biofilms, decreased the number of viable bacteria by about 5 orders, demonstrating the efficacy of this methodology as a disinfection system.

Keywords Biofilm; Pseudomonas; titania; photocatalysis; antibiofilm coating; mesoporous

Journal Pre-proof 1. Introduction Bacterial biofilms are complex structures consisting of microorganisms attached to a surface and embedded in a self-produced matrix [1]. Within these structures, bacterial cells are protected from cleaning agents, antibiotics and environmental factors, so that they are more resistant than their planktonic counterparts [2-5]. Strategies employed to combat biofilms include chemical and physical treatments such as application of disinfectants, antibiotics and ultrasound [6-8]. The high resistance of

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biofilm cells and the risk to human health and the environment by the use of increasing

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bactericide doses led to research into safer alternative control strategies. Among these,

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the use of photocatalytic titania (TiO2) has been proposed as inexpensive, safe and effective [9, 13]. Titania-based antibacterial materials provide two great advantages

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over other antimicrobial systems: a) titanium dioxide has broad spectrum bactericidal

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activity against Gram-negative and Gram-positive bacteria, fungi and multi-drug resistant strains [14, 15], b) titania nanocomposites are environmentally friendly,

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releasing no potentially toxic nanoparticles into the media [16], and c) titania-based

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coatings are commercially available [17]. The mechanism of photocatalytic disinfection by titania involves its photoexcitation by exposure to UVA radiation (320-400 nm),

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which generates highly toxic reactive oxygen species (ROS) in the presence of O 2. ROS, mainly superoxide anion and hydroxyl radical, produce strong oxidative cell damage, with consequent bacterial death [9-12]. Several studies have demonstrated the excellent killing properties of titania powder in solution or immobilized on a surface, on both planktonic cells and biofilms of several microorganisms [13-15, 18-22]. However, to the best of our knowledge, this property has not yet been demonstrated in biofilms of the pathogen Pseudomonas aeruginosa, where the lack of cell inactivation has been explained by the very high resistance of the sessile cells to ROS [19, 20]. P. aeruginosa is a Gram-negative bacterium, present in terrestrial and aquatic environments, which produces robust biofilms [23, 24]. It has detrimental effects on industrial applications, causing serious economic damage [25, 26], and is a major

Journal Pre-proof opportunistic human pathogen that can cause severe complications in patients who are immunocompromised or have burn wounds or cystic fibrosis [27]. It is used as a model organism in biofilm studies [24]. In order to find surfaces that improve the antibiofilm effect on P. aeruginosa, the aim of this study was to analyze the effect of mesoporous titania coatings obtained by sol-gel and Evaporation-Induced Self-Assembly method (EISA). Mesoporous films obtained by these techniques have been applied in technologies such as catalysis,

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sorption, filtration, sensor devices and regulation of adhesion of human osteoblastic

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cells [28-30]. Recently, we demonstrated the nanotopological-based antibiofilm

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properties of mesoporous silica surfaces in P. aeruginosa [31]. In this work mesoporous titania coatings obtained by the same synthesis strategy were tested to

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add the killing action of an innovative photocatalytic surface to the inhibitory biofilm

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formation effect previously demonstrated, searching for efficient solutions to eradicate P. aeruginosa biofilms. Mesoporous films are characterized by their simplicity, low

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production cost, nanostructural flexibility and robustness for the preparation of highly

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controlled nanoscale topographies. We tested the antibiofilm action of titania coatings

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with different degrees of porosity and structural forms, and found promising results.

2. Materials and Methods

2.1. Preparation and characterization of titania thin films Titania films were prepared by spin-coating (3,100 rpm for 30 seconds) on standard microscope glass slides at 35 ºC solution temperature and 30% relative humidity (RH). Slides were first washed with neutral detergent, then sequentially rinsed with Milli-Q water, acetone and isopropanol, and finally, dried under nitrogen flow. To obtain mesoporous films, two surfactant templates were added to a TiCl4 ethanol solution: Brij-58 [C16H33(OCH2CH2)20- OH] and Pluronics-F127 (F127) [HO(CH2CH2O)106(CH2CH(CH3)O)70-(CH2CH2O)106OH]. The final composition of the

Journal Pre-proof precursor solutions were: TiCl4:EtOH:H2O:surfactant equal to 1:40:10:0.0075. After deposition, the samples were placed in a 50% RH chamber for 24 h and subjected to a thermal consolidation treatment consisting of two successive stages of 24 h at 60 and 130 ºC, respectively. To stabilize the overall structure and remove the organic template, a final thermal treatment at 350 or 500 ºC (temperature ramp of 2 ºC min-1) was performed for 2 h. Non-mesoporous titania films were obtained by the same protocol but in the absence of surfactants. Slides without titania were assayed as

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controls. Scanning electron microscopy (SEM) images of these films were obtained

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using a Carl Zeiss NTS Supra 40 electron microscope (Cambridge, UK). Titania

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crystalline structure was analysed by Grazing Incidence X-ray Diffraction (GIXD) using a Copper K alpha Panalytical Empyrean diffractometer (Almelo, The Netherlands), and

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Raman spectroscopy using a LabRAM HR (Horiba Jobin Yvon, Kyoto, Japan).

2.2. Bacterial strain, growth conditions and biofilm formation

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The study was conducted using the prototypical P. aeruginosa strain PAO1 (B.

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W. Holloway). Bacteria were cultured at 37 ºC in complete LB broth (10 g tryptone, 5 g yeast extract and 5 g NaCl, bringing the volume up to 1000 ml with distilled water); for

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growth in solid medium, 15 g l-1 agar were added. Uncoated and coated glass slides employed as surfaces for biofilm formation were sterilized by soaking in 70% ethanol and subsequent evaporation at 60 ºC before use in biological assays. For biofilm formation, the slides were placed horizontally at the bottom of 100 ml glass beakers and covered in 10 ml of suspensions of overnight cultures diluted to an OD650 0.01 in LB. The beakers were capped with cotton plugs and incubated at 37 ºC for 24 h without shaking.

2.3. Irradiation source Irradiations were performed on a bench with two Philips TDL 18W/08 tubes, in which more than 95% of the emission is at 365 nm. The tubes were mounted on

Journal Pre-proof aluminium anodized reflectors that enhance the fluence rate on the section to be irradiated. The incident fluence was measured at the surface of the suspension or biofilm with a 9811.58 Cole-Palmer Radiometer (Cole-Palmer Instruments Co., Chicago, IL).

2.4. UVA treatment Slides carrying 24 h “preformed” biofilms were removed from the beakers and

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washed once with distilled sterile water to eliminate unattached cells. The slides were

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then placed in small Petri dishes (5 cm diameter) open to air and covered with 5 ml

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saline solution (NaCl 0.1 M). Ultraviolet absorption by TiO2 films has been reported as stable under similar conditions to those employed in this study, even after 24 h of

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immersion, proving the high chemical stability of these films [32].

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A set of biofilms was irradiated from above at a fluence rate of 20 W m -2 for 180 minutes (total dose 216 KJ m -2). During this procedure, the Petri dishes containing the

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slides were maintained in an ice-bath to prevent overheating. As control, another set of

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2.5. Biofilm evaluation

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biofilms was maintained under similar conditions, but in the dark.

Two methods were employed to quantify biofilm formation and viability following the photocatalytic treatment: colony-forming unit (CFU) count and membrane integrity evaluation. To count the number of CFU, the slides carrying the biofilms were removed from the beakers before or after UVA exposure and washed with distilled water to eliminate unattached cells. The bacterial biomass was scraped from the glass with a sterile plastic spatula, recovered in tubes containing 1 ml of saline solution, and homogenized by vigorous vortexing. Appropriate dilutions of these suspensions were plated on LB solid medium. Plates were incubated in the dark at 37 ºC and the colonies were counted after incubation for 24-48 h. The results were expressed in CFU cm -2.

Journal Pre-proof Membrane integrity was evaluated by staining the biofilms with the fluorescent stains SYTO 9 and Propidium iodide (PI). The slides carrying the biofilms were removed from the beakers, washed with distilled water, immersed in a solution containing 3.5 µM SYTO 9 and 20 µM PI in distilled water, and incubated in the dark for 15 min at room temperature. Biofilm top images were obtained using an Olympus BX51 epifluorescence microscope. The percentage of red (dead) cells in top images was

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2.6. Calculation of antibioadhesion and killing efficiency

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calculated using Image J software [33].

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The percentages of antibioadhesion (inhibition of biofilm formation before UVA

efficiencies were calculated as follows:

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A= 100 [(CFUPre-Ti - CFUPre-C)/CFUPre-C]

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treatment, A) and killing (decrease of biofilm survival after UVA treatment, K)

CFUPre-Ti : number of CFU cm -2 recovered from preformed biofilms grown on each

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titania surface.

surface without titania.

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CFUPre-C : number of CFU cm -2 recovered from preformed biofilms grown on the control

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K= 100 [(CFUUVA - CFUPre)/CFUPre)] CFUUVA: number of CFU cm -2 recovered from UVA-exposed biofilms grown on a given surface.

CFUPre : number of CFU cm -2 recovered from preformed biofilms grown on the same surface before UVA-exposure.

2.7. Calculation of total antibacterial efficiency The total antibacterial efficiency (antibioadhesion + photocatalytic killing) of the different coatings was represented as the percentage of CFU recovery after treatment and calculated as follows: CFU recovery (%) = 100 (CFUUVA /CFUPre-C)

Journal Pre-proof CFUUVA: number of CFU cm -2 recovered from UVA-exposed biofilms grown on a given surface. CFUPre-C : number of CFU cm -2 recovered from preformed biofilms grown on the control surface (non-TiO2) before UVA exposure.

2.8. Statistical analysis All samples were analyzed in triplicate. Data are represented as means 

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standard deviations. The significance of each treatment was evaluated by an unpaired

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two-tailed Student’s t test with confidence levels >95 % (i.e., P<0.05 was considered

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significant).

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3. Results

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3.1. Characterization of titania films

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Two sets of titania films with different nano-topography were prepared by combining sol-gel chemistry and EISA, using Brij-58 and Pluronics-F127 as templates.

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The use of Brij-58 and Pluronics-F127 surfactants enable different lyotropic mesophases to be obtained, thereby creating surfaces with different pore sizes after template removal (MB and MF, respectively); non-mesoporous films (NM) were obtained in the absence of surfactants. In order to obtain differential degree of anatase phase, one set of films was exposed to 350 ºC and the other to 500 ºC. Fig. 1 shows representative SEM images to illustrate the variety of topographies attained, where the diverse nanostructures can be observed. High pore size was attained for the F127 films with similar topographies regardless of the thermal treatment. On the contrary, Brij-58 films treated at 500 °C showed a higher pore interconnectivity compared to those treated at 350 ºC, which is evidenced as small grooves in the surface (Fig. 1). In order to evaluate the anatase degree into the titania

Journal Pre-proof layers, GIXD and Raman spectroscopy were conducted. Fig. 2 shows representative results with F127 surfaces; similar results were obtained with Brij-58 films (data not shown). The zone of the spectra where specific peaks were observed is shown. Unlike titania coatings treated at 350 ºC, titania systems treated at 500 ºC showed a high Xray diffraction peak at 25.27º (Fig. 2a) and Raman shift at 144 cm -1 (Fig. 2b), two characteristics of the anatase phase [34]. These results demonstrate greater prevalence of anatase in titania films treated at 500 ºC than in those treated at 350 ºC

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(hereinafter, anatase and amorphous titania, respectively). Film thickness between 120

3.2. Effect of titania films on biofilm formation

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and 130 nm were observed in cross-section SEM micrographs.

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Surface topography is a key factor in cell adhesion of microorganisms to abiotic

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surfaces; controlling biofilm formation by tuning surfaces at nanoscale level has been proposed as a promising antibiofilm strategy [35-45]. We demonstrated previously that

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mesoporous silica thin coatings obtained by the EISA method are able to inhibit P.

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aeruginosa biofilm formation, a valuable technological advancement in comparison to other approaches [31]. Accordingly, we analyzed the effect of mesoporous titania

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surfaces produced by the same synthesis strategy on biofilm formation. P. aeruginosa biofilms were grown on the different surfaces (preformed biofilm) and the CFU number was evaluated before UVA treatment (Fig. 3). Fig. 3 shows that a significant lower number of cells was recovered from biofilms developed on mesoporous surfaces (P<0.05 for amorphous F127 and anatase Brij-58 and P<0.005 for anatase F127) compared to control (non-TiO2) and non-mesoporous titania coatings. To quantify the antibiofilm effect, the percentage of antibioadhesion was calculated as described in Section 2.6 (Table 1). It was demonstrated that, with the exception of amorphous Brij-58 films, mesoporous surfaces inhibited biofilm formation with effects ranging from 73.75% (amorphous F127) to 88.75 % (anatase F127). Positive values represent no inhibition of biofilm formation.

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3.3. Effect of titania films on photocatalytic killing Biofilms grown on the different surfaces where then exposed to UVA radiation. Table 1 shows that killing efficiency (see Section 2.6) is more effective on titania surfaces than on controls without titania. The strongest bactericidal effect was obtained with anatase non-mesoporous films (99.999%). On the other hand, the results presented in Fig. 3 show the residual number of CFU upon the UVA treatment. It

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should be noted that this number depends both on the initial cell number in the

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preformed biofilm and the photocatalytic effect. Fig. 3 shows that UVA exposure

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decreased cell viability by at least two orders in biofilms grown on titania surfaces compared to those grown on the control surface, with anatase Brij-58 being the most

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efficient antibiofilm surface (Fig. 3). Biofilms grown under similar conditions but

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maintained in the dark did not show significant changes in cell viability (data not shown). In order to better illustrate the efficacy (antibioadhesion + photocatalytic killing)

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of the different coatings, the total antibacterial efficiency (see Section 2.7) is shown in

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Fig. 4 (the higher antibacterial efficiency, the lower CFU recovery). The most effective result was observed in anatase coatings, followed by amorphous coatings, and further

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away by non-titania coatings.

Permeabilization of cell membrane by photocatalytic treatment was also evaluated as a measure of cell death. As shown in Fig. 5, upon exposure to UVA radiation, cell viability decreased, even in biofilms formed on surfaces without titania (8.3% red cells), when compared to dark controls (1.7% red cells). However, the presence of photocatalytic surfaces significantly increased the degree of membrane damage compared to non-exposed surfaces (P0.0005). Amorphous TiO2 films did not differ from each other and neither did anatase coatings (Fig. 5); however, anatase films were significantly more deleterious than amorphous films (P0.05).

4. Discussion

Journal Pre-proof In this study, we have described simple titania coatings with a double antibiofilm effect: inhibition of biofilm formation and cell killing upon UVA irradiation. Inhibition of biofilm formation by nanostructured titania coatings has been explained by the reduction of the effective contact between the cells and the surface, as suggested in a previous study by this group employing nanoporous silica coatings as antibiofilm surfaces [31]. In our study, biofilm formation decreased in the presence of the greatest pore size, both in amorphous and anatase coatings. A striking difference was observed

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between amorphous and anatase mesoporous Brij-58 films: cell attachment was only

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reduced in the latter. This may be due to the nanostructure of the amorphous film,

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whose size pore seems to be smaller than that of anatase (Fig. 1). Antibacterial treatments based on the use of UV light and titania coatings have

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proven to be efficient in destroying biofilms of pathogens such as Listeria

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monocytogenes, Candida albicans, Streptococcus, Enterococcus and bacteria present in stagnant pond waters [15, 46, 47]. However, this methodology has not been

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successful in the case of P. aeruginosa biofilms [19, 20]. Several explanations have

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been put forward, and it was concluded that the lack of cell inactivation could be due to the strong defensive response of attached cells, which were able to increase their

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resistance to the ROS generated by photoactivated titania [19]. To the best of our knowledge, we demonstrate here for the first time P. aeruginosa biofilm inactivation by photocatalysis employing simple titania coatings. The difference between our proposal and the other studies may lie in the surface preparation. In the aforementioned studies, thick films were constituted by preformed 50 nm titania agglomerates [20] or 21 nm P25 Degussa nanoparticles [19], whereas in our study, thin, transparent coatings were obtained from in-situ synthesis using inorganic precursors (sol-gel chemistry). The high antibacterial effect of the surfaces described in our study could be related to a greater production of highly reactive ROS, which are responsible for the oxidative damage [4750].

Journal Pre-proof Most research on titania has focused on its crystalline rutile and anatase phases [51]. Anatase surfaces give rise to significantly higher photoactivity than rutile, owing to their higher surface area as well as higher photoactivity per unit of surface area [51-53]; amorphous titania has received less attention, despite its importance for a number of applications [54]. We observed in this study that anatase was more efficient as an antibiofilm strategy than the amorphous form (Figs. 3, 4 and 5); in addition, porosity did not have a significant effect on killing efficiency (Table 1).

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When membrane integrity was used as a viability indicator (Fig. 5), it was

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observed that photoactivated titania efficiently killed biofilm cells, according to the CFU

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counts shown in Fig 3. However, the degree of cell damage varied widely depending on the technique employed. According to the CFU counts, photocatalysis reduced

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viability by 3 to 4 orders, while according to the membrane damage assessment, this

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parameter ranged from about 50 to 85%. Bacterial death is commonly quantified by the inability to develop colonies on solid media, but other viability indicators with different

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susceptibility to a given stress agent can be employed [55, 56]. Bosshard et al. [56]

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demonstrated that cell functions are inactivated sequentially depending on the UVA dose received, being membrane integrity the last cellular function affected by UVA

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radiation. This finding would explain the discrepancy mentioned above, and, even more importantly, confirms the irreversible cell death. In summary, we describe herein photocatalytic titania coatings with two effects on P. aeruginosa biofilms: inhibition of biofilm formation and a strong bactericidal effect under UVA exposure. In biofilms developed on anatase Brij-58 mesoporous coatings, the photocatalytic treatment decreased the number of viable cells by about 5 orders and produced the highest percentage of cell membrane disruption, compared to nontreated biofilms grown on surfaces without titania, demonstrating the efficacy of this methodology as a disinfection system. The preparation of these coatings is simple, flexible on potentially any surface, the precursors are easily available molecules, and

Journal Pre-proof orderly, highly reproducible transparent films are obtained. In short, we propose the use of these coatings in diverse applications, mainly for food or industrial facilities.

Acknowledgements This work was supported by CNEA, Consejo Nacional de Investigaciones Científicas y Técnicas (PIP 00186) and Agencia Nacional de Promoción Científica y

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Tecnológica (PICT 2969, PICT 2087). M.P., M.G.B. and P.N.C. are staff members of

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Consejo Nacional de Investigaciones Científicas y Técnicas.

J.W. Costerton, Z. Lewandowski, D. E. Caldwell, D. R. Korber, H. M. Lappin-

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Journal Pre-proof Figure captions

Fig. 1. Top-view SEM of the titania films tested in this study. Titania films prepared by sol-gel and EISA method were exposed to a final thermal treatment at 350 ºC or 500 ºC. NM: non-mesoporous films; MB: mesoporous Brij-58 films; MF: mesoporous Pluronics-F127 films. Scale bar: 50 nm. Representative films of

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three replicates are shown.

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Fig. 2. XRD patterns (a) and Raman spectra (b) of Pluronics-F127 templated samples

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subjected to final thermal treatment at 350 ºC or 500 ºC.

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Fig. 3. Effect of titania surfaces on biofilm formation and photocatalytic effect.

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24 h biofilms (Preformed biofilm) were obtained on Control (non-TiO2) or titania coated surfaces (amorphous NM, MB or MF and anatase NM, MB or MF) and exposed to UVA

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at a fluence rate of 20 W m -2 (UVA-treated biofilm). Appropriate dilutions of the

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bacterial biomass were plated for CFU count before and after UVA exposure to determine efficiency of biofilm formation and cell survival. Error bars represent the

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standard deviations of a least three independent experiments. a (P0.05) and b (P0.005) represent significant difference between preformed biofilms grown on titania and the control surface before UVA exposure. c (P0.0005) represents significant difference between biofilms grown on each titania surface and the control surface after UVA exposure.

Fig. 4. Total antibacterial efficiency of titania coatings 24 h biofilms obtained on control (non-TiO2) or titania coated surfaces (amorphous NM, MB or MF and anatase NM, MB or MF) were exposed to UVA or maintained in the dark. Total antibacterial efficiency (antibioadhesion + photocatalytic killing) of the

Journal Pre-proof different coatings is represented as the percentage of CFU recovery (Section 2.7): the higher antibacterial efficiency, the lower CFU recovery.

Fig. 5. Effect of photocatalytic titania surfaces on membrane integrity. Biofilms grown on Control (no TiO2) or titania coated surfaces (amorphous NM, MB or MF and anatase NM, MB or MF) were maintained in the dark or exposed to UVA at fluence rate of 20 W m -2 for 180 min. Representative epifluorescence images of

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biofilms stained with the stains SYTO 9 and PI are shown. The experiments were

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repeated at least three times. Each value is the mean of three independent tests  SD.

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The bar represents 150 nm.

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Graphical abstract

Journal Pre-proof Table 1 Percentage of antibioadhesion (A) and cell killing (K) efficiency Antibiofilm

Control

effect (%)

TiO 2 amorphous

TiO2 anatase

NM

MB

MF

NM

MB

MF

0

12.50

25.00

-73.75

12.50

-82.50

-88.75

K

-98.875

-99.991

-99.991

-99.990

-99.999

-99.995

-99.977

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A

Journal Pre-proof Highlights

 Mesoporous titania films obtained by sol-gel inhibit biofilm growth of P. aeruginosa  UVA exposed mesoporous coatings efficiently killed P. aeruginosa biofilms

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 Titania coatings can be used as versatile photocatalytic disinfection systems

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5