Antimicrobial and Antibiofilm Properties of Graphene Oxide on Enterococcus faecalis.

Cecilia Martini,Massimo Cordaro,Nicola Maria Grande,Valentina Palmieri,Massimiliano Papi,Francesca Bugli,Raffaella Castagnola,Francesca Longo,Maurizio Sanguinetti,Margherita Cacaci,Luca Marigo

doi:10.3390/antibiotics9100692

Abstract

The aim of this study was to evaluate the antibacterial properties of graphene oxide (GO) against Enterococcus faecalis in vitro conditions and when used to coat dentin surface to prevent E. faecalis adhesion. The ATCC strain of E. faecalis 29212 has been used to perform a viability test. The pellet was suspended in ultrapure water, NaCl, PBS buffer, CaCl2 and MgCl2, Luria−Bertani broth solutions. The viability was evaluated by the colony forming unit counting method. Atomic force microscopy images and the measure of surface zeta potential variation were analyzed. Dentin discs were covered with a film of GO (n = 15) or were not treated (n = 15). Bacterial suspension was added to each sample of dentine discs and microbial counts were calculated. Statistically significant differences between two groups were assessed by a two-tailed unpaired t-test. Bacteria cell morphology was investigated with scanning electron microscopy. The highest growth inhibition was obtained in ddH2O and CaCl2 solution while, in PBS and NaCl, GO had poor antibacterial efficacy with a growth enhancing effect in the latter. GO on dentin discs demonstrated high antibacterial activity. GO film has demonstrated acceptable adhesion properties to root dentin and a role in the inhibition of bacterial film proliferation and biofilm formation.

Highlights

The main goal in the management of endodontic infections is to eliminate the microbial biofilm from the root canal system and to provide favorable root canal sealing
In order to evaluate the different effects of graphene oxide (GO) against E. faecalis, we decided to analyze the vitality of bacterial cells in contact with GO in different solutions
NaCl, PBS, CaCl2 and ddH2 O were tested since it has been demonstrated that GO has different stability and, different effects on bacteria depending on the surrounding solutions and their concentration (Table 1) [24]

Summary

Introduction

The main goal in the management of endodontic infections is to eliminate the microbial biofilm from the root canal system and to provide favorable root canal sealing. Research is focused on the development of new coating material that can prevent the adhesion and the biofilm formation of microorganisms on medical devices [3,4,5]. The cells in biofilm are more resistant to antimicrobial therapies and to the host immune response making these infections hard to be treated, as antibiotics are usually active against planktonic cells that are actively reproducing. The use of metal or carbon nanoparticles has become an interesting approach to prevent microbial adhesion: they appear to be safe, not expensive allowing to overcome the issue of the antibiotic resistance [7]. Three main antimicrobial activities [10]

Objectives

Methods

Results

Discussion

Conclusion