Photophysical and antibacterial activity of light-activated quaternary eosin Y

Abstract

AbstractThe functional characteristics of a new eosin dye with biocidal quaternary ammonium group (E) were studied in aqueous solution and in organic solvents of different polarity. The spectral properties depend on the nature and polarity of the respective solvents. The antimicrobial activity of compound E has been tested in vitro against Gram-negative bacteria (Escherichia coli, Acinetobacter johnsoni and Pseudomonas aeruginosa), Gram-positive bacteria (Sarcina lutea and Bacillus cereus) and the antifungal activity was tested against the yeasts Candida lipolytica in solution and after treated on cotton fabric. Broth dilution test has been used for quantitative evaluation of the antimicrobial activity of compound E against the model strains. The ability of compound E to inhibit the growth of model Gram-negative P. aeruginosa strain was assessed after 16 h of incubation in presence and absence of light. These experiments were conducted in planktonic format in solution and on cotton fabric. The results suggest that the new compound is effective in treating the relevant pathogens with better results being obtained by irradiation with light. In this case the quaternary ammonium group promotes the binding of eosin Y moiety to the bacterial cell wall thus accelerating bacterial photo inactivation.