title: Antibacterial efficacy of photosensitizer functionalized biopolymeric nanoparticles in the presence of tissue inhibitors in root canal.
abstract: BACKGROUND
  Application of antibacterial nanoparticles to improve root canal disinfection has received strong interest recently. The current study aims to assess the antibacterial effect of a novel photosensitizer (rose bengal functionalized chitosan nanoparticles [CSRBnp]) to eliminate bacteria in the presence of various root canal constituents that are known to inhibit the antibacterial efficacy of root canal disinfectants.
  
  
  METHODS
  The synthesized CSRBnp were evaluated for size, charge, and singlet oxygen release. The antibacterial effect of CSRBnp was tested on planktonic Enterococcus faecalis with or without pretreatment by using different inhibiting agents such as dentin, dentin-matrix, pulp tissue, bacterial lipopolysaccharides, and bovine serum albumin (BSA). Bacterial survival was assessed in a time-dependent manner. The antibacterial effects after photodynamic activation on CSRBnp, a cationic photosensitizer (methylene blue), and an anionic photosensitizer (rose bengal [RB]) in the presence of inhibitors were also evaluated.
  
  
  RESULTS
  CSRBnp were 60 ± 20 nm in size and showed reduced rate of singlet oxygen release as compared with methylene blue and RB. Pulp and BSA inhibited the antibacterial effect of CSRBnp (without photoactivation) significantly (P < .05) even after 24 hours of interaction. In case of photodynamic therapy, the pulp and BSA significantly inhibited the antibacterial activity of all 3 photosensitizers. CSRBnp showed residual effect and completely eliminated the bacteria after 24 hours of interaction after photodynamic therapy.
  
  
  CONCLUSIONS
  The inherent antibacterial activity of polycationic chitosan nanoparticles and the singlet oxygen released after photoactivation of RB synergistically provided CSRBnp the potential to achieve significant antibacterial efficacy even in the presence of tissue inhibitors within root canals.
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: akishen@gmail.com.
authors.forename: Anil
authors.initials: A
authors.lastname: Kishen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D058491:Bacterial Load / Q000187:drug effects; D001704:Biopolymers / Q000494:pharmacology*; D048271:Chitosan / Q000494:pharmacology*; D003782:Dental Pulp / Q000382:microbiology; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology; D013293:Enterococcus faecalis / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008422:Materials Testing; D008751:Methylene Blue / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects; D053758:Nanoparticles; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D012395:Rose Bengal / Q000494:pharmacology*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D026082:Singlet Oxygen / Q000493:pharmacokinetics / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D001704:Biopolymers; D008070:Lipopolysaccharides; D017319:Photosensitizing Agents; D026082:Singlet Oxygen; D012395:Rose Bengal; D012710:Serum Albumin, Bovine; D048271:Chitosan; D008751:Methylene Blue
keywords: Antibacterial; chitosan; nanoparticles; tissue inhibitors