A cost-effective combination of Rose Bengal and off-the-shelf cationic polystyrene for the photodynamic inactivation of Pseudomonas aeruginosa.

Two new photoactive materials have been prepared, characterized and tested against Pseudomonas aeruginosa bacteria (planktonic suspension). The synthesis of the polymeric photosensitizers can be made at a multigram scale, in few minutes, starting from inexpensive and readily available materials, such as Rose Bengal (photosensitizer) and ion exchange resins Amberlite® IRA 900 (macroporous) or IRA 400 (gel-type) as cationic polystyrene supports. The most notable feature of these systems is their notable bactericidal activity in the dark (4-5 log10 CFU/mL reduction of the population of P. aeruginosa) which becomes enhanced upon irradiation with visible light (to reach a total reduction of 8 log10 CFU/mL for the macroporous polymer at a fluence of 120 J/cm2 using green light of 515 nm).