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Eradication of Gram-Positive and Gram-Negative Bacteria by Photosensitizers Immobilized in Polystyrene

Authors

  • Faina Nakonechny,

    1. Department of Chemical Engineering, Biotechnology and Materials, Ariel University Center of Samaria, Ariel, Israel
    2. The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
    3. Samaria and Jordan Rift Valley Regional R&D Center, Ariel, Israel
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  • Anna Pinkus,

    1. Department of Chemical Engineering, Biotechnology and Materials, Ariel University Center of Samaria, Ariel, Israel
    2. The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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  • Smadar Hai,

    1. Department of Chemical Engineering, Biotechnology and Materials, Ariel University Center of Samaria, Ariel, Israel
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  • Ortal Yehosha,

    1. Department of Chemical Engineering, Biotechnology and Materials, Ariel University Center of Samaria, Ariel, Israel
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  • Yeshayahu Nitzan,

    1. The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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  • Marina Nisnevitch

    Corresponding author
    • Department of Chemical Engineering, Biotechnology and Materials, Ariel University Center of Samaria, Ariel, Israel
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Corresponding author email: marinan@ariel.ac.il (Marina Nisnevitch)

Abstract

Immobilization of photosensitizers in polymers opens prospects for their continuous and reusable application. Methylene blue (MB) and Rose Bengal were immobilized in polystyrene by mixing solutions of the photosensitizers in chloroform with a polymer solution, followed by air evaporation of the solvent. This procedure yielded 15–140 μm polymer films with a porous surface structure. The method chosen for immobilization ensured 99% enclosure of the photosensitizer in the polymer. The antimicrobial activity of the immobilized photosensitizers was tested against Gram-positive and Gram-negative bacteria. It was found that both immobilized photosensitizers exhibited high antimicrobial properties, and caused by a 1.5–3 log10 reduction in the bacterial concentrations to their total eradication. The bactericidal effect of the immobilized photosensitizers depended on the cell concentration and on the illumination conditions. Scanning electron microscopy was used to prove that immobilized photosensitizers excited by white light caused irreversible damage to microbial cells. Photosensitizers immobilized on a solid phase can be applied for continuous disinfection of wastewater bacteria.

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