Effect of Silver Nanoparticles on Blue Light Phototoxicity against Fusobacterium nucleatum

Uziel Jeffet,Nir Sterer,Arkadi Rahmanov,Shiri Livne

doi:10.3390/biophysica1040029

Abstract

A previous study showed that sub-lethal exposure of blue light caused cell membrane damage in Fusobacterium nucleatum (Fn). The aim of the present study was to test the combined effect of blue light and silver nanoparticles against Fn. Bacterial suspensions were exposed to blue light (400–500 nm) with or without silver nanoparticles (10 nm). Exposed and non-exposed samples were studied for malodor production (Odor judge scores), VSC levels (Halimeter), reactive oxygen species (ROS) production (fluorimeter), and bacterial cell membrane damage (fluorescence microscopy). The results showed that combining blue light exposure and silver nanoparticles significantly reduced malodor and VSC production by Fn concomitant with increased ROS levels and bacterial cell membrane damage. These results suggest that silver nanoparticles may increase blue light phototoxicity against Fn.

Highlights

The proteolytic activity of anaerobic Gram-negative oral bacteria such as Fusobacterium nucleatum has been associated with oral malodor and gum disease [1]
These are further metabolized, yielding malodorous compounds such as the volatile sulfide compounds (VSC) [2] that are felt during exhalation and speech
The antimicrobial effect of silver nanoparticles combined with blue light against antibiotic resistant Pseudomonas aeruginosa was shown [9]

Summary

Introduction

The proteolytic activity of anaerobic Gram-negative oral bacteria such as Fusobacterium nucleatum has been associated with oral malodor and gum disease [1] These bacteria break down oral proteins and glycoproteins into their amino acid building blocks. Silver nanoparticles are considered a promising antimicrobial agent due to the multitarget action of silver [3]. Due to their antimicrobial activity [4], low cytotoxicity, and low immunogenicity [5] silver nanoparticles have multiple biomedical applications. Their antibacterial mechanism is not yet clear, several mechanisms have been proposed.

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