Enhancement of the killing effect of low-temperature plasma on Streptococcus mutans by combined treatment with gold nanoparticles

Abstract

BackgroundRecently, non-thermal atmospheric pressure plasma sources have been used for biomedical applications such as sterilization, cancer treatment, blood coagulation, and wound healing. Gold nanoparticles (gNPs) have unique optical properties and are useful for biomedical applications. Although low-temperature plasma has been shown to be effective in killing oral bacteria on agar plates, its bactericidal effect is negligible on the tooth surface. Therefore, we used 30-nm gNPs to enhance the killing effect of low-temperature plasma on human teeth.ResultsWe tested the sterilizing effect of low-temperature plasma on Streptococcus mutans (S. mutans) strains. The survival rate was assessed by bacterial viability stains and colony-forming unit counts. Low-temperature plasma treatment alone was effective in killing S. mutans on slide glasses, as shown by the 5-log decrease in viability. However, plasma treatment of bacteria spotted onto tooth surface exhibited a 3-log reduction in viability. After gNPs were added to S. mutans, plasma treatment caused a 5-log reduction in viability, while gNPs alone did not show any bactericidal effect. The morphological changes in S. mutans caused by plasma treatment were examined by transmission electron microscopy, which showed that plasma treatment only perforated the cell walls, while the combination treatment with plasma and gold nanoparticles caused significant cell rupture, causing loss of intracellular components from many cells.ConclusionsThis study demonstrates that low-temperature plasma treatment is effective in killing S. mutans and that its killing effect is further enhanced when used in combination with gNPs.

Papain gel containing methylene blue for simultaneous caries removal and antimicrobial photoinactivation against Streptococcus mutans biofilms

“…9G,H ). A previous study showed TEM images of S. mutans that had been killed by a combination of cold plasma and gold nanoparticles 40 .…”

Effect of cold plasma on maintaining the quality of chub mackerel (Scomber japonicus): biochemical and sensory attributes

“…In comparison with conventional technologies, ACP treatment possesses several advantages, such as inexpensive operation costs, short treatment times at low temperatures and freedom from chemicals and water. This advanced alternative approach has been extensively explored and successfully applied to surface modification, water disinfection, cancer treatment, wound healing and blood coagulation . ACP has also been employed in the food industry .…”

“…This advanced alternative approach has been extensively explored and successfully applied to surface modification, water disinfection, cancer treatment, wound healing and blood coagulation. [8][9][10] ACP has also been employed in the food industry. 11 Nevertheless, few data are available about CP treatment for seafood to date.…”

Non-thermal plasma accelerates the healing process of peripheral nerve crush injury in rats

“…Thus far, strong anti-bacterial [16][17][18] and anti-inflammatory [19,20] activities of NTP have been reported, and a possible role of NTP in treating cancer has also been suggested [21,22]. In dentistry, NTP has not only been utilized as a bactericidal agent [17], but also for tooth whitening [23,24] and preservation [25]. However, the most promising medicinal property of NTP is the acceleration of wound healing [14].…”