Esmaeil Darabpour - Department of Biology-Faculty of Science-Shahid Chamran University of Ahvaz-Ahvaz-Iran
Nasim Kashef - Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
Behzad Karimi - Department of Inorganic Pigment and Glazes, Institute for Color Science and Technology, Tehran, Iran

Background and Aim:Recently, nanotechnology-based approaches have been directed toward developing novel nanotechnology platforms to combat biofilms. Here we aimed to evaluate PDT of Pseudomonas aeruginosa biofilms using graphene oxide quantum dot-methylene blue conjugate.Methods:At first, graphene oxide quantum dot (GOQD) was synthesized and characterized by several techniques. Methylene blue (MB) was immoblized on to the negatively charged graphene oxide quantum dot (GOQD) through electrostatic interaction. In the next step, in vitro phototoxic effect of the above photosensitizer system (GOQD-MB conjugate) on 24 h-old biofilms was assessed using laser light (650 nm). Also, in vitro cytotoxicity and photo toxicity of the conjugated product was assessed on human dermal fibroblast. Finally, we used atomic force microscopy (AFM) to determine the effect of GOQD-MB-mediated PDT on P. aeruginosa biofilm structure.Results:The successful conjugation of MB to the GOQDs surface was mainly confirmed by FT-IR spectroscopy. The metabolic activity of P. aeruginosa biofilm following GOQD-MB-mediated PDT was significantly lower than MB-mediated PDT. Also, only 28.5% of the fibroblasts were photo-inactivated in the presence of GOQD-MB conjugate. AFM confirmed severe alternations in the biofilm structure and cell morphology of P. aeruginosa after GOQD-MB-mediated PDT treatment.Conclusion:In summary, the photo-activated MB-GOQD particles resulted in complete elimination of the biofilm structure of P. aeruginosa, this finding suggest that the MB-GODQ has great potential as sensitizer for PDT of burn wound infections.

Nano-PDT, Biofilm, Wound infection