Killing of S. mutans Bacteria Using a Plasma Needle at Atmospheric Pressure

Abstract

Abstract-Streptococcus mutans (S. mutans) bacteria were killed using a low-power millimeter-size atmospheric-pressure glowdischarge plasma or plasma needle. The plasma was applied to a culture of S. mutans that was plated onto the surface of an agar nutrient in a Petri dish. S. mutans is the most important microorganism for causing dental caries. A spatially resolved biological diagnostic of the plasma is introduced, where the spatial pattern of bacterial colonies in the sample was imaged after plasma treatment and incubation. For low-power conditions that would be attractive for dentistry, images from this biological diagnostic reveal that S. mutans was killed within a solid circle with a 5-mm diameter, demonstrating that site-specific treatment is possible. For other conditions, which are of interest for understanding plasma transport, images show that bacteria were killed with a ringshaped spatial pattern. This ring pattern coincides with a similar ring in the spatial distribution of energetic electrons, as revealed by Abel-inverted images of the glow. The presence of the radicals OH and O was verified using optical-emission spectroscopy.

Atomic oxygen patterning from a biomedical needle-plasma source

“…The dimensions are matched to experimental reports of Goree et al 3,4 and Sakiyama et al 10 on the devices killing pattern of S. Mutans bacteria samples. A 5 mm dielectric barrier (5 0 ) sits on a grounded plate at a distance of 3 mm below the RF driven pin.…”

“…The plasma needle 1 is a cold atmospheric plasma device under study for biomedical applications 2,3,5 . The device consists of a thin tungsten wire driven by a radio frequency voltage surrounded by quartz tubing guiding helium flows of up to 2 slpm around the wire.…”

“…The device consists of a thin tungsten wire driven by a radio frequency voltage surrounded by quartz tubing guiding helium flows of up to 2 slpm around the wire. A critical factor in its efficacy is attributed to the mixing of the helium carrier gas with air 4,10 . Mixing results in generation of reactive oxygen nitrogen species(RONS) culminating in oxidative and nitrosative stress to exposed cells.…”

Comparison of the characteristics of atmospheric pressure plasma jets using different working gases and applications to plasma-cancer cell interactions

“…2,[29][30][31][32] Since the critical radicals to cell death are O, NO, and OH radicals, the richness of these species may make the plasma jets suitable for biomedical applications. [33][34][35] The excitation temperatures of He or Ar lines were measured by using the Boltzmann plot -method. [36][37][38] The atomic emission intensity (I pq ) of the transition from level p to level q depends on the transition probability (A pq ) and absolute population of the atomic level (n p ), as shown in the following equation; I pq = n p A pq hν(where h is the Planck constant and ν is the photon frequency corresponding to the p→q transition).…”

Reduction of breakdown threshold by metal nanoparticle seeding in a DC microdischarge

“…Although such a microdischarge is spatially confined compared to a traditional low-pressure discharge, the normal glow properties of a nonthermal discharge still apply, such as an electron temperature, Te, which is several orders of magnitude larger than the gas temperature, Tg [3][4][5]. Many applications have been explored to exploit this excess electron energy and drive optical or chemical processes such as vacuum-ultraviolet light sources [6], biomedical systems [7,8], nanoparticle synthesis [9,10], and plasma ignition [11]. However in atmospheric air, even with a small inter-electrode separation of less than 1 mm, a sizeable voltage (upwards of 4 to 5 kV) may still be required to initiate breakdown.…”