title: Antibiofilm action of a toluidine blue O-silver nanoparticle conjugate on Streptococcus mutans: a mechanism of type I photodynamic therapy.
abstract: The objective of this study was to evaluate the anti-biofilm efficacy of photodynamic therapy by conjugating a photosensitizer (TBO) with silver nanoparticles (AgNP). Streptococcus mutans was exposed to laser light (630 nm) for 70 s (9.1 J cm(-2)) in the presence of a toluidine blue O-silver nanoparticle conjugate (TBO-AgNP). The results showed a reduction in the viability of bacterial cells by 4 log10. The crystal violet assay, confocal laser scanning microscopy and scanning electron microscopy revealed that the TBO-AgNP conjugates inhibited biofilm formation, increased the uptake of propidium iodide and leakage of the cellular constituents, respectively. Fluorescence spectroscopic studies confirmed the generation of OH(•) as a major reactive oxygen species, indicating type I phototoxicity. Both the conjugates down-regulated the expression of biofilm related genes compared to TBO alone. Hence TBO-AgNP conjugates were found to be more phototoxic against S. mutans biofilm than TBO alone.
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , India.
authors.forename: Lama
authors.initials: L
authors.lastname: Misba
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , India.
authors.forename: Shatavari
authors.initials: S
authors.lastname: Kulshrestha
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , India.
authors.forename: Asad U
authors.initials: AU
authors.lastname: Khan
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D003731:Dental Caries / Q000382:microbiology / Q000628:therapy; D006801:Humans; D053768:Metal Nanoparticles / Q000627:therapeutic use; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology; D012834:Silver / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects / Q000502:physiology; D014048:Tolonium Chloride / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D014048:Tolonium Chloride; D012834:Silver
keywords: Biofilm; gene expression; photodynamic therapy; toluidine blue O–silver nanoparticle conjugate; type I