title: Antibiofilm efficacy of photosensitizer-functionalized bioactive nanoparticles on multispecies biofilm.
abstract: BACKGROUND
  Newer disinfection strategies based on antibacterial nanoparticles and photodynamic therapy (PDT) aim to eliminate residual biofilm bacteria during root canal treatment. The aim of the current study was to test the newly developed rose bengal-functionalized chitosan nanoparticles (CSRBnps) for their interaction/uptake with monospecies bacteria/biofilm and assess their antibiofilm efficacy on a multispecies biofilm model in vitro.
  
  
  METHODS
  The interaction of CSRBnps with bacterial cells was conducted using atomic force microscopy. Their membrane-damaging effect was determined by measuring the absorbance at 260 nm (OD260nm) using Enterococcus faecalis. The penetration of CSRBnps into E. faecalis biofilms was evaluated using confocal laser scanning microscopy (CLSM). Multispecies biofilms of Streptococcus oralis, Prevotella intermedia, and Actinomyces naeslundii were grown on dentin sections for 21 days to assess the antibiofilm efficacy. The biofilms were subjected to PDT (60 J/cm(2)) using CSRBnps and rose bengal. The treated/untreated biofilms were examined under scanning electron microscopy and CLSM.
  
  
  RESULTS
  The CSRBnps synthesized were 60 ± 20 nm and showed absorption spectra similar to rose bengal. Atomic force microscopy showed adherence of CSRBnps to bacteria, roughening of cell surface, and cell disruption after PDT. CSRBnp treatment resulted in significantly increased bacterial membrane damage (P < .05). CSRBnps exhibited deeper penetration into the biofilm structure. Scanning electron microscopy and CLSM confirmed the complete disruption of multispecies biofilm with a reduction in viable bacteria and biofilm thickness (P < .05).
  
  
  CONCLUSIONS
  These novel photosensitizer functionalized bioactive nanoparticles with increased affinity to bacterial cell membrane, higher penetration into biofilm structure, and enhanced ability to eliminate clinically relevant multispecies bacterial biofilm present a potential antibiofilm agent for root canal disinfection.
authors.affiliation: Discipline of Endodontics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Annie
authors.initials: A
authors.lastname: Shrestha
authors.affiliation: Discipline of Endodontics, University of Toronto, Toronto, Ontario, Canada. Electronic address: anil.kishen@dentistry.utoronto.ca.
authors.forename: Anil
authors.initials: A
authors.lastname: Kishen
mesh_terms: D000190:Actinomyces / Q000187:drug effects / Q000648:ultrastructure; D018441:Biofilms / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D048271:Chitosan / Q000737:chemistry / Q000627:therapeutic use*; D003804:Dentin / Q000382:microbiology; D013293:Enterococcus faecalis / Q000187:drug effects / Q000648:ultrastructure; D006801:Humans; D008422:Materials Testing; D050296:Microbial Viability / Q000187:drug effects; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry / Q000627:therapeutic use*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000737:chemistry / Q000627:therapeutic use*; D018713:Prevotella intermedia / Q000187:drug effects / Q000648:ultrastructure; D012395:Rose Bengal / Q000737:chemistry / Q000627:therapeutic use*; D019533:Streptococcus oralis / Q000187:drug effects / Q000648:ultrastructure
chemical_list: D017319:Photosensitizing Agents; D012395:Rose Bengal; D048271:Chitosan
keywords: Chitosan; functionalized nanoparticles; multispecies biofilms; photodynamic therapy