Nanoparticle-based Antimicrobial Photochemotherapy in Biofilms

Date: 12/07/2007
Time: 12:00 pm
Location: 322 CSC
Speaker: Dr. Nikos Soukos, Director, Applied Molecular Photomedicine Laboratory, Forsyth Institute

Photodynamic therapy (PDT) has been suggested as an alternative to chemical antimicrobial agents to eliminate bacterial species. PDT is based on the concept that non-toxic photosensitizers (PS) can be preferentially localized in certain tissues and subsequently activated by light of the appropriate wavelength to generate singlet oxygen and free radicals that are cytotoxic to cells of the target tissue. Recently, studies in PDT have focused on the use of polymer-based nanoparticles for PS delivery and release systems, in particular those with biocompatible and biodegradable polymers. FDA-approved polymeric nanoparticles of poly(lactic-co-glycolic acid) (PLGA) have been used as a drug delivery system for various PS. Once encapsulated within PLGA, the excited states of the PS are quenched, which results in a loss of phototoxicity. When the nanoparticles are incubated with cells, they show a time-dependent release of the PS, which then regains its phototoxicity and results in an activatable PDT-nanoagent. Although PLGA nanoparticles loaded with various compounds (e.g. antibiotics) have been used for bacterial targeting, the use of PLGA nanoparticles as carriers of PS has not been explored in antimicrobial PDT. Here we present, for the first time, the use of PLGA nanoparticles loaded with the PS methylene blue (MB) to phototargeting oral pathogens.