Biomedical Engineering Reference
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(a)
(b)
(c)
FIGURE 7.12
Silver nanoparticles (Ag50.PVP) diffusing close to a group of cultured V79
cells, which were immersed in physiologic saline (KRPG-buffer) and viewed with dark field
microscopy. Particles appear blue, green, and yellow due to their different plasmon reso-
nance. In parts (a), (b), and (c) (taken at intervals of ca. 0.3 s) particles outside cells appear at
different positions due to Brownian motion. Arrows point to particles attached to cell surface.
Bar: 20 µm.
microscopy was introduced, which allows us to view single 60 nm gold NP on
color images of cultured cells (Wang et al. 2010). Provided that cells can be main-
tained under sufficient culture conditions, it may be used for directly observing
particles together with cells in special experimental chambers over many hours.
Within the NanoGEM project we adapted and improved this method so that V79
cells could be observed together with diffusing silver nanoparticles (Ag50.PVP,
see Figure 7.12). By this, the diffusion coefficient of single particles close to cells
could be measured. Future experiments will now give insight into preferential sites
of particle adherence and/or particle uptake. However, compared to the approach
described earlier, information retrieved from 3-dimensional dark field microscopy
is far more complex because time-lapse series of z-stacks need to be evaluated.
Furthermore, color information appears important at least if gold or silver NP are
investigated, whose plasmon resonance is subject to change upon particle uptake
in vesicles (Wang et al. 2010). Nevertheless, future image analysis methods should
allow us to quantify the uptake of NP into single cells. In a next step this meth-
odology could then be used to attribute biologic effects to the particle load at the
single cell level.
ACKNOWLEDGMENTS
The work was supported by grants of the German Ministry of Education and Science
(BMBF, 03X0105) and the Northrhine Westphalian Ministry of Innovation, Science,
Research and Technology (FH-GP 2008-9/Lipinski).
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