The effect of indocyanine green loaded on a novel nano-graphene oxide for high performance of photodynamic therapy against Enterococcus faecalis

Background: Recently developed photodynamic therapy (PDT) has gained attention for achieving effective root canal disinfection. Using an optimized nontoxic photosensitizer (PS), such as indocyanine green (ICG), is an imperative part of this technique. Therefore, the objective of the current study was to improve ICG photo dynamic properties through incorporation of ICG into nano-graphene oxide (NGO) in order to produce NGO-ICG as a new PS and also to assess the antimicrobial effects of NGO-ICG against Enterococcus faecalis after photo dynamic therapy. Materials and methods: NGO-ICG was synthesized based on oxidation of graphite flakes and direct loading of ICG onto NGO. NGO-ICG formation was confirmed using the Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and UV vis spectrometry. The antimicrobial and anti-biofilm potential of NGO-ICG-PDT against E. faecalis was assessed via colony forming unit and crystal violet assays, respectively. Results: FT-IR, SEM and UV vis spectrometry confirmed successful synthesis of NGO-ICG containing 200 g/mL of ICG. NGO-ICG-PDT at an energy density of 31.2 J/cm(2) showed a significant reduction (2.81 log) in the count of E. faecalis (P < 0.05). NGO-ICG-PDT significantly reduced the biofilm formation ability of E. faecalis up to 99.4% (P < 0.05). The overall antimicrobial and anti-biofilm potential of NGO-ICG-PDT was higher than PDT based on ICG (1000 pg/mL) (47% and 21%, respectively). Conclusion: Because NGO-ICG-PDT showed a significant reduction in the number and biofilm formation ability of E. faecalis at low ICG concentrations (200 mu g/mL), it could be a new approach to adjuvant treatment of endodontic infections.