Killing of adherent oral microbes by a non-thermal atmospheric plasma jet

Abstract

Atmospheric plasma jets are being intensively studied with respect to potential applications in medicine. The aim of this in vitro study was to test a microwave-powered non-thermal atmospheric plasma jet for its antimicrobial efficacy against adherent oral microorganisms. Agar plates and dentin slices were inoculated with 6 log 10 c.f.u. cm "2 of Lactobacillus casei, Streptococcus mutans and Candida albicans, with Escherichia coli as a control. Areas of 1 cm 2 on the agar plates or the complete dentin slices were irradiated with a helium plasma jet for 0.3, 0.6 or 0.9 s mm "2 , respectively. The agar plates were incubated at 37 6C, and dentin slices were vortexed in liquid media and suspensions were placed on agar plates. The killing efficacy of the plasma jet was assessed by counting the number of c.f.u. on the irradiated areas of the agar plates, as well as by determination of the number of c.f.u. recovered from dentin slices. A microbekilling effect was found on the irradiated parts of the agar plates for L. casei, S. mutans, C. albicans and E. coli. The plasma-jet treatment reduced the c.f.u. by 3-4 log 10 intervals on the dentin slices in comparison to recovery rates from untreated controls. The microbe-killing effect was correlated with increasing irradiation times. Thus, non-thermal atmospheric plasma jets could be used for the disinfection of dental surfaces.

In-situ UV Absorption Spectroscopy for Monitoring Transport of Plasma Reactive Species through Agarose as Surrogate for Tissue

“…5). An absorption peak at 209.2 nm was detected for NaNO 2 and 201.4 nm for HNO 3 . A shoulder of a peak was detected for H 2 O 2 because the H 2 O 2 peak is expected to exist at a much shorter wavelength of 160 nm [27,28].…”

“…The concentration of H 2 O 2 , NaNO 2 , HNO 3 and O 2 delivered and / or generated through the agarose film was quantified. The APPJ appears to deliver and / or generate these RONS to different depths within the agarose target and via a slow molecular transport phenomenon.…”

“…treatment of chronic wounds, [1] bacterial infections [2] dental decay [3] and cancer [4]. The non-thermal nature of the APPJ source enables it to deliver therapeutic doses of reactive oxygen and nitrogen species (RONS) to the biological target without inducing thermal damage.…”

Influence of a plasma jet on the viability of Candida albicans

“…Recently, some research groups have dealt with the inactivation of yeasts using different atmospheric pressure plasma sources [12][13][14][15][16][17][18]. A He-O 2 (2 L min -1 , 3% O 2 ) plasma source was used for inactivation of C. albicans cells inoculated in Sabouraud's medium [15].…”

Plasmas meet plasmonics

“…Moving slightly away from nanoplasmonics, there has been a lot of excitement in the last few years centred around the use of atmospheric plasmas in medicine and health care [209]. Specific applications include (but are not limited to): wound treatment, tissue engineering [209], treatment of skin diseases such as Rosacea [210], antimicrobial applications [211], inducing cancer cell apoptosis [212] and minimizing adenovirus infectivity [213]. In particular, it has also been recently shown that cold plasmas may be used to selectively kill cancer cells without damaging surrounding healthy cells [214].…”