Eradication of gram-positive and gram-negative bacteria by photosensitizers immobilized in polystyrene

Faina Nakonechny, Anna Pinkus, Smadar Hai, Ortal Yehosha, Yeshayahu Nitzan, Marina Nisnevitch

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


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.

Original languageEnglish
Pages (from-to)671-678
Number of pages8
JournalPhotochemistry and Photobiology
Issue number3
StatePublished - May 2013


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