Chemistry Reference
In-Depth Information
Plasma
Cell
Excited species
DNA
Cell wall/
membrane
UV-radiation
Ions
+
electrons
+
+
+
+
-
Proteins
-
-
-
+
+
FIGURE 8.42
Scheme of plasma agencies acting with cell components.
8.2.3.5.2 Active Agencies
Active agents from the plasma that may act with treated surfaces are (Figure 8.42)
•
UV radiation: In an atmospheric plasma jet are identified radiation in the
UV-A (315-400 nm), UV-B (280-315 nm), UV-C (200-280 nm), and VUV
range (115-200 nm) regions, but emission can be changed for selected
discharge conditions [271,274,275].
•
Charged particles: The interaction of active plasmas with living tissue
investigated with FE-DBD is mainly determined by the action of charged
species [117].
•
Reactive neutral species, radicals: Examples are reactive oxygen species
such as O, O
2
,O
3
, OH, and H
2
O
2
and reactive nitrogen species like NO and
NO
2
[276,277]. The nature of active species generated by the plasmas in
inert feed gas is influenced by the composition of the air environment, e.g.,
content of water vapor [278].
Thermal effects can be mostly neglected because no essential gas heating could be
observed in the applied plasma sources.
8.2.3.5.3 Selected Applications
The decrease of the bacterial population on various inanimate targets by cold non-
thermal atmospheric pressure plasmas is well known [264]. Because medicine knows
that bacterial colonization of chronic wounds slows healing process, microorganism
inactivation by plasma is also important for treatment of living tissue.
The antibacterial activity of atmospheric pressure plasma jet against wound
pathogens was tested in vitro with various species of bacteria situated on agar
plates [279].
