Antimicrobial activity of plasmonic photocatalysts in polymer nanohybrid layers against nosocomial pathogens

Antimicrobial activity of plasmonic photocatalysts in polymer nanohybrid layers against nosocomial pathogens

Szabolcs Péter Tallósy

, Elisabeth Nagy

, Eleonóra Fodor

, László Janovák

, Judit Ménesi

, Norbert Buzás

, Imre Dékány

1

Institute of Clinical Microbiology and Diagnostic, Faculty of Medicine, University of Szeged, Semmelweis str. 6. H-6725 Szeged, Hungary

2

Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged Aradi v.t.1. Hungary

3

Nanocolltech Ltd H-6722 Szeged, Gogol u 9/B, Hungary

In the health care an increase of nosocomial infections can be observed, which is caused by multidrug-resistant microorganisms, such as methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumanni and Pseudomonas aeruginosa. Beside the antibiotic and conventional treatments it is very important to prevent the spread of nosocomial infections. Antimicrobial surfaces can solve this problem, because of killing wide spectrum of microorganisms upon a contact and in the air. Titanium dioxide have been developed as a photocatalyst and proved its antimicrobial effect under UV light irradiation. Photocatalysts can produce free radicals, which can kill microorganisms via destroying the cell wall and the DNA. Photocatalysts can be modified differently, so the wavelength of the excitation light can be extended to the visible region. Many methods have been optimized to prove the antimicrobial effect of photocatalysis.

In this study we tested modified TiO2 and ZnO photocatalysts against pathogen microorganisms, namely Acinetobacter baumanni, Escherichia coli, Pseudomonas aeruginosa, methicillin resistant Staphylococcus aureus, ESBL producing Enterobacter cloacae, and naturally occurring airborne microorganisms. The photocatalysts were prepared with spray coating technique on glass samples for the microbiological tests. The antibacterial effect of the photocatalysts was tested with different methods and with the standard ISO 27447:2009. The destruction of the bacterial cell wall component was examined with transmission electronmicroscope and the survival ratio of the bacteria was investigated with fluorescence microscopy supported by fluorimetric measurements.

With the photo reactive coatings an extensive disinfectant system (air cleaning with the reactive lamp, floor and wall disinfection with self-cleaning system) was developed and successfully prepared.

The antimicrobial effect on the surface was proved with microbiological investigations and with the associated standard. The photocatalysts could kill 99% of the investigated bacteria in different layers after two hours of illumination with visible light. The reactive lamp with photocatalytic inner coating could kill 96% of naturally occurring airborne microorganisms after 48 hours of visible light illumination. All of the investigated cell wall components were degraded after 1 hour of illumination.

The electronmicroscopical results and the microbiological measurements were proved with fluorescence techniques, fluorimetric measurements and toxicity tests. (POSTER)

Acknowledgement: This work was financed by European Union under contract no. TÁMOP-4.2.2.A- 11/1/KONV-2012-0047, TÁMOP-4.2.2/B-10/1-2010-0012 and DEVTEGEN PROJECT

HUSRB/1002/214/078.

References

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205-216(12)

[2] Krýsa J, Musilová E, Zita J.; Critical assessment of suitable methods used for determination of antibacterial properties at photocatalytic surfaces.J Hazard Mater. 2011 Nov 15;195:100-6

[3] Kőrösi L., et al.: Colloids and Surfaces A: Physicochem. Eng. Aspects 319 (2008) 136.