1. Are Nanomaterials used in Dental
Treatments Neurotoxic?
Alexandra Isabel Sveinsen Treimo1 (aitreimo@gmail.com), Katrine Borgå1, Jan Tore
Samuelsen2, Ragnhild E. Paulsen3, Kirsten Eline Rakkestad2
1Department of Biosciences, University of Oslo (IBV/UiO); 2Nordic Institute of Dental Materials
(NIOM); 3School of Pharmacy, University of Oslo
Background
Nanoparticles are widely used in production of
dental materials, such as coating materials for
dental implants and mouthwashes among
others. The use of nanomaterials is increasing,
and thereby the risk of health problems
increases.
Research indicates that nanoparticles can pass
the blood-brain barrier and locate in the central
nervous system. Using in vitro studies, the aim
of this master thesis is to get a better
understanding of the possible neurotoxic effects
of silica nanoparticles (SiNP).
Research aims
Study the dose-response relationship
between nanoparticle exposure and cell death
Study how nanoparticles of different size
induce oxidative stress and cellular reactive
oxygen species (ROS)
Identify and describe effects of the
nanoparticles on cell morphology
Compare the effects of similar exposure in
two different batches of the same cell line
Materials and Methods
Cell line used: PC12 cells from the adrenal
gland of Rattus norvegicus (rat).
Toxicant: Silica particles that are <10 nm and
<50 nm
Aspects and methods:
Pictures of the cells before and after exposure
are taken in all experiments. Exposure time 24h
and 48h.
• Changes in the morphology of the cells:
Measured by using a neurite outgrowth kit
and then read in fluorescence plate reader
(ongoing)
• Cell death: Measured using MTT assay
Results
Cells were exposed for 24 hours and 48 hours and
viability was measured using MTT assay. The results
are shown in figure 1. Although no significant differences were
found between serum deprived control cells and the particle
exposed cells (Dunnets Multiple Comparison test: p > 0.05), the
preliminary results indicate concentration dependent cytotoxicity.
Figure 1: Cell viability of PC12 cells exposed to silica nanoparticles. The cells have been exposed to Si10 and Si50 for 24 hours
and 48 hours, respectively. The results are presented as the mean ± SD (n=3).
Figure 2 shows representative images of control cells and cells
exposed to Si10 at the lowest particle concentration tested.
There were visible morphological changes already after 24 hrs
exposure, with rounded, vacuolized cells.
Figure 2: Picture 1 shows control with serum, picture 2 shows cells exposed for 24 hours (Si10 3,125 μg/mL), picture 3 shows the
cells after 48 hours (Si10 3,125 μg/mL). Pictures are taken at 20x magnitude.
Summary
• The results indicate dose dependent cytotoxicity of SiNPs
• SiNPs induce morphological changes at concentrations with no
measurable effect on cell viability.
0
50
100
150
200
250
300
350
Viablecellsrelativetoserumfreecontrol(%)
Cell viability of PC12 cells, 48h exposure
0
50
100
150
200
250
300
350
Viablecellsrelativetoserumfreecontrol(%)
Cell viability of PC12 cells, 24h exposure
1 2 3
Further studies
• The MTT results must be verified by other methods
(measurement of growth pattern and cell death)
• Study the potential of the nanoparticles to induce oxidative
stress and generate cellular ROS
• Study possible relationship between oxidative stress and
morphology