Polymer-Immobilized Photosensitizers for Continuous Eradication of Bacteria

• Main Authors: Anton Valkov, Faina Nakonechny, Marina Nisnevitch
• Format: Article
• Language: English
• Published: MDPI AG 2014-08-01
• Series: International Journal of Molecular Sciences
• Subjects: photodynamic antimicrobial chemotherapy; immobilization; photosensitizers; Rose Bengal; methylene blue; polystyrene; antibacterial activity
• Online Access: http://www.mdpi.com/1422-0067/15/9/14984

The photosensitizers Rose Bengal (RB) and methylene blue (MB), when immobilized in polystyrene, were found to exhibit high antibacterial activity in a continuous regime. The photosensitizers were immobilized by dissolution in chloroform, together with polystyrene, with further evaporation of the solvent, yielding thin polymeric films. Shallow reservoirs, bottom-covered with these films, were used for constructing continuous-flow photoreactors for the eradication of Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and wastewater bacteria under illumination with visible white light using a luminescent lamp at a 1.8 mW·cm−2 fluence rate. The bacterial concentration decreased by two to five orders of magnitude in separate reactors with either immobilized RB or MB, as well as in three reactors connected in series, which contained one of the photosensitizers. Bacterial eradication reached more than five orders of magnitude in two reactors connected in series, where the first reactor contained immobilized RB and the second contained immobilized MB.