Biomedical Applications of Low Temperature Atmospheric Pressure
Plasmas to Cancerous Cell Treatment and Tooth Bleaching
Gan Young Park1, Myoung Soo Kim3, June Ho Byun1,2, Kyong Tai Kim4, Gyoo Cheon Kim5, and Jae Koo Lee3
1
Institute of Health Sciences, Biomedical Center (BK21), Gyeongsang National University School of Medicine, Jinju, 660751, Republic of Korea
2
3
Department of Oral and Maxillofacial Surgery, Gyeongsang National University School of Medicine, Jinju, 660-751,
Republic of Korea
Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784,
Republic of Korea
4
Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology,
Pohang, 790-784, Republic of Korea
5
Department of Oral Anatomy, School of Dentistry, Pusan National University, Yangsan, 626-810, Republic of Korea
Abstract: The biomedical applications of low temperature atmospheric pressure
plasmas to cancerous cell treatment and tooth bleaching were investigated. Gold
nanoparticles conjugated with cancer-specific antibodies have been introduced to
cancerous cells to enhance selective killing of cells, and the mechanism of cell
apoptosis induced by plasma has been investigated. Tooth exposed to plasma jet
with hydrogen peroxide has become brighter and the productions of hydroxyl
radicals from hydrogen peroxide have been enhanced by plasma exposure.
Keywords: atmospheric pressure plasma, cancerous cell, tooth bleaching
1. Introduction
Low temperature atmospheric pressure plasmas
(APPs) have been developed for the past decade and
attracting great interests due to their interesting
characteristics and wide ranges of applicability.1,2)
The APPs have been finding new applications in the
medical field thanks to their nonthermal property to
allow them to interact with the living tissues, cells,
synthetic polymeric biomaterials, and inorganic
materials in the human body.3) It has been
investigated the biomedical applications of APPs
such as blood coagulation, wound healing,
decontamination, and cancer cell treatment.4-8)
A novel approach to treat cancerous cells using
APPs has been suggested to achieve the selective
cell death.9,10) Gold nanoparticles conjugated with a
cancer-specific antibody for the protein overexpressed in cancerous cells were bound to cells and
the enhanced death of the cells with the antibody-
conjugated gold nanoparticles was demonstrated
while exposing the cells to APPs, suggesting the
selective cancer cell treatment.
Another interesting biomedical application of APPs
is to use them for tooth bleaching that is a popular
esthetic therapy in dentistry.11,12) Conventional tooth
bleaching therapy normally exposes tooth deposited
bleaching gel including hydrogen peroxide to light
sources so that the decomposition of hydrogen
peroxide into ·OH is enhanced by heating the
bleaching gel. It was demonstrated that tooth
exposed to APP jet with hydrogen peroxide gets
brighter compared to the case treated by hydrogen
peroxide alone.
In this paper, we show the cancerous cell treatment
of APPs with gold nanoparticles conjugated with
cancer-specific antibody, the mechanism of
apoptosis induced by APPs, and the effect of APP
jet on the external and internal tooth bleaching.
Figure 2. Enhancement of cell death rates by plasma treatment
plus TFR-gNP and EGFR-gNP in SCC25 cells.10)
Figure 1. Comparison of the cell death rate which is
significantly increased in the case of anti-FAK antibodyconjugated gold nanoparticles.9)
controlled air plasma, the cell death rates were 14%,
36%, and 74%, respectively, as shown in Fig. 1.
2.1 Cancerous cells treatments
Since the epidermal growth receptor (EGFR) and
transferring receptor (TFR) have been known to be
over-expressed in many oral cancer cells, these
receptors were chosen to be targets for plasma
cancer therapy.
The conventional therapies for cancerous diseases
are based on surgical extirpation, chemotherapy,
radiation. However, these therapies have not yet
made a conquest in the war with cancers and they
have a limitation in use due to their significant sideeffects. It has been reported that non-thermal APPs
were effective in killing cancer cells.8,13,14) The
cancer treatment by APPs has to achieve selectivity
between normal and cancerous cells so that it is used
as a reliable cancer therapy.
In order to examine the selective effect of plasma
exposure with anti-EGFR antibody-conjugated gNPs
(FAK-gNPs) or anti-TFR antibody-conjugated gNPs
(TFR-gNPs), SCC25 oral cancer cells were cultured
in four different media: (a) pure media; (b) media
containing gNPs; (c) media containing TFR-gNPs;
and (d) media containing EGFR-gNPs. When these
four groups of cells were exposed to plasma for 30 s,
the cell death rate were 5%, 21%, 66%, 92%,
respectively, as shown in Fig. 2.
Gold nanoparticles (gNPs) are widely used as
diagnostic and drug delivery tools recently thanks to
the advances in nanotechnology. It was suggested
that gNPs can be conjugated with cancer-specific
antibody and the conjugated gNPs are able to be
selectively bound to the targeted cancerous cells and
the cancerous cells bound to the gNPs can be
dramatically affected by the exposure to APPs
compared to normal cells.13)
It was reported that APPs can induce apoptosis in
mammalian cells, which is a programmed cell
death.8) However, the mechanism of apoptosis
induced by plasma treatment has been unclear yet.
2. Biomedical Applications of APPs
Three cell groups were prepared to examine the
enhancement and the selectivity of plasma treatment
with FAK-gNPs: (1) cells cultured in only media, (2)
cells cultured in media containing gNPs, and (3)
cells cultured in media containing FAK-gNPs. When
the three groups of cells were exposed to the dose-
The mechanism of apoptosis was investigated via
Western blot analysis, as shown in Fig. 3(a). It was
demonstrated from the detection of the increase of
gamma-H2A.X at 3 h after treatment that DNA
damage such as DNA double strand breaks (DSBs)
was induced by plasma treatment. The cleaved
caspase-3 was clearly observed at 3 h following
plasma exposure indicating caspase-associated
apoptosis. The air plasma treatment also induced the
accumulation of the p53. Figure 3(b) shows the
analysis of the cellular location of cytochrome C via
the immunocytochemistry. For the control, the
Figure 4. The external bleaching effect of plasma treatment.
Photographs of canine tooth used (a) before, (b) after treatment
for the experimental group only, (c) followed by treatment for
control groups, demonstrating typical results in the experimental
group(A’→A) and the control group (B’→B).11)
Figure 3. (a) Western blot analysis. (b) The cellular images of
cytochrome C release by immunocytochemistry.15)
cytochrome C was localized in the mitochondria
represented by green spots. Cytochrome C was
released from the mitochondria to the cytosol at 1h
(smeared green flouorescent) and gradually released
with time. It is likely that the cellular organelles such
as mitochondria were damaged by plasma exposure.
It could be suggested that the effects of plasma on
cells involve genetic signaling cascade from DNA
damage and nongenetic physical damage in cellular
membrane system.
2.2 Tooth Bleaching
In dental clinic, the bleaching material including
high concentration of hydrogen peroxide is
deposited on tooth and it is exposed to light sources
to enhance the reactivity of the bleaching material.
The substantial role of the light sources, however,
has been in a controversy.
It was suggested to use APP jet for tooth bleaching
on behalf of light sources while using hydrogen
peroxide.11) The extracted human teeth were used to
demonstrate the effect of APP jet on tooth bleaching
while dropping hydrogen peroxide (28%, 20μl every
30 seconds). The teeth used were cut in half
longitudinally, and the control group was treated by
using hydrogen peroxide alone. Figure 4 shows the
changes of tooth surface brightness after
treatment of hydrogen peroxide with and without
plasma exposure. The tooth treated by plasma with
hydrogen peroxide became brighter than the control
group (Fig. 4(c)). It is likely that the enhanced
efficacy of tooth bleaching is caused by the increase
of ·OH generation from hydrogen peroxide by
plasma treatment.
It was demonstrated the effect of nonthermal APPs
on intracornal tooth bleaching in blood stained
human teeth.16) The extracted single-root human
teeth were used and standard access cavities inside
teeth were created with a diamond-coated bur with a
high-speed engine. Then they were artificially
stained by the hemoglobin-rich hemolysed blood.
The control groups were treated with 30% hydrogen
peroxide (20 μl every 5 min.) alone in the pulp
chamber for 30 min. and the experiment groups were
treated with 30% hydrogen peroxide (20 μl every 5
min.) with the APP jet in the pulp chamber for 30
min., as shown in Figs. 5(a) and 5(b).
It was shown that the tooth color of the experiment
group and the control group after 30 min. treatment.
It was observed a clear high efficacy for the APP jet
and hydrogen peroxide bleaching compared to the
control group. The average (n=20) ΔE value after
treatment for 30 min. was 9.24 in the experiment
group and 4.47 in the control group. It suggests that
the nonthermal APP jet could bleach teeth within a
very short time and it has potential use in the
intracoronal bleaching of intrinsic discolored teeth.
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Figure 5. The process of intracoronal bleaching using
nonthermal atmospheric pressure plasma in the pulp chamber.
(a) Schematic diagram of the plasma device and (b) photograph
of the process.16)
3. Summary
In this paper, we discussed about cancerous cell
treatment and tooth bleaching of biomedical
applications using low temperature APPs. The novel
method to treat cancerous cells used gold
nanoparticles conjugated with cancer-specific
antibody for the protein over-expressed in cancerous
cells and the high selectivity for the targeted cell
death was achieved by exposing to APPs. Low
temperature APP jet was introduced to tooth
bleaching therapy and it was demonstrated that the
use of APP jet with hydrogen peroxide induced the
significant color change of tooth stained by extrinsic
and intrinsic causes.
Acknowledgments
This work was supported by the National
Research Foundation of Korea Grants (NRF2010-355-D00089 and R01-2007-000-10730-0)
and the Brain Korea 21 program funded by the
Korean Government
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