title: Photodynamic effects of methylene blue-loaded polymeric nanoparticles on dental plaque bacteria.
abstract: OBJECTIVE
  Photodynamic therapy (PDT) is increasingly being explored for treatment of oral infections. Here, we investigate the effect of PDT on human dental plaque bacteria in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles with a positive or negative charge and red light at 665 nm.
  
  
  METHODS
  Dental plaque samples were obtained from 14 patients with chronic periodontitis. Suspensions of plaque microorganisms from seven patients were sensitized with anionic, cationic PLGA nanoparticles (50 µg/ml equivalent to MB) or free MB (50 µg/ml) for 20 min followed by exposure to red light for 5 min with a power density of 100 mW/cm2 . Polymicrobial oral biofilms, which were developed on blood agar in 96-well plates from dental plaque inocula obtained from seven patients, were also exposed to PDT as above. Following the treatment, survival fractions were calculated by counting the number of colony-forming units.
  
  
  RESULTS
  The cationic MB-loaded nanoparticles exhibited greater bacterial phototoxicity in both planktonic and biofilm phase compared to anionic MB-loaded nanoparticles and free MB, but results were not significantly different (P > 0.05).
  
  
  CONCLUSIONS
  Cationic MB-loaded PLGA nanoparticles have the potential to be used as carriers of MB for PDT systems.
authors: Applied Molecular Photomedicine Laboratory, The Forsyth Institute, Cambridge, Massachusetts 02142, USA.
authors: Vanja
authors: V
authors: Klepac-Ceraj
authors: Niraj
authors: N
authors: Patel
authors: Xiaoqing
authors: X
authors: Song
authors: Colleen
authors: C
authors: Holewa
authors: Chitrang
authors: C
authors: Patel
authors: Ralph
authors: R
authors: Kent
authors: Mansoor M
authors: MM
authors: Amiji
authors: Nikolaos S
authors: NS
authors: Soukos
mesh_terms: D000838:Anions; D001419:Bacteria / Q000187:drug effects*; D018407:Bacterial Physiological Phenomena / Q000187:drug effects; D001672:Biocompatible Materials / Q000008:administration & dosage; D018441:Biofilms / Q000187:drug effects*; D002412:Cations; D055113:Chronic Periodontitis / Q000188:drug therapy / Q000382:microbiology; D003773:Dental Plaque / Q000382:microbiology*; D004337:Drug Carriers; D006801:Humans; D019344:Lactic Acid; D008751:Methylene Blue / Q000494:pharmacology* / Q000627:therapeutic use; D053758:Nanoparticles; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology* / Q000627:therapeutic use; D010933:Plankton / Q000187:drug effects* / Q000502:physiology; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer
chemical_list: D000838:Anions; D001672:Biocompatible Materials; D002412:Cations; D004337:Drug Carriers; D017319:Photosensitizing Agents; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D008751:Methylene Blue