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

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.

Membrane Oxidation in Cell Delivery and Cell Killing Applications

“…98–102 A report from Nisnevitch and co-workers shows a scanning electron microscope (SEM) image of E. coli cells that survived irradiation in the presence of methylene blue immobilized in polystyrene. 103 These cells showed compromised membranes evidenced by large, spherical membrane protrusions, often referred to as blebs. Whether these “blebs” are structures enclosed by dual bilayers (both inner and outer membrane) remain unclear.…”

Superior performance of macroporous over gel type polystyrene as a support for the development of photo-bactericidal materials

“…aPDI can be applied using soluble 12 or supported photosensitizers. [13][14][15][16][17][18][19][20] A broad number of chemical families have been proposed as effective generators of ROS, especially singlet oxygen ( 1 O 2 ). 21 Among those molecules, xanthenic dyes, phenothiazinium compounds, porphyrins and phthalocyanins have been studied.…”

“…[24][25][26][27][28][29][30][31][32][33][34][35] Regarding the supports for the photoactive agents, a variety of materials have been described in the literature, like polyurethane, cellulose, nylon, chitosan, silica and polystyrene. [13][14][15][16][17][18][19][20] This last polymer is one of the most popular supports employed so far, dating back to the pioneering works of Schaap and Neckers. 36 Polystyrene is a versatile system, used in applications as diverse as fluorescence sensing 37 or catalysis.…”

“…38 In catalysis, this polymer is the basic scaffold of many ion exchange resins 39 and as a matter of fact some of those resins were employed very early to support ionic photosensitizers for the generation of singlet oxygen. [40][41][42][43][44][45][46] The vast majority of reported systems consist of photosensitizers covalently attached (or embedded) onto the so called gel-type resins, comprised of polystyrene with very low porosity. [47][48][49] In contrast with the frequently used gel-type supports, there is another kind of resin of technological interest: macroporous resins are made of highly-crosslinked polystyrene and have the unique property of having permanent pores allowing effective mass transfer throughout the entire polymeric matrix.…”

Otimização da inativação fotodinâmica de <i>E. coli</i> por fotossensibilizadores veiculados por nanopartículas de sílica

“…Segundo Nakonechny, F, et al, 2013, entre a variabilidade de suportes para a veiculação de fotossensibilizadores, até o momento os mais estudados são: Poli (cloreto de estireno-co-…”