28
spectrometry analysis [ 24 , 25 ]. In vitro studies have shown that mesenchymal and
adipose-derived stem cells labeled with gold nanoparticles did not demonstrate
changes in cell function or proliferation, and no toxicity was apparent [ 23 , 25 ].
However, it is hypothesized that the intracellular biocompatibility of gold nanopar-
ticles is influenced by the presence of free radicals which can lead to oxidative stress
and cell damage [ 66 ]. Also, before the translation of nanoparticles to clinical prac-
tice, there is a need to address issues like opsonization, phagocytosis by macro-
phages, and sequestration to the liver and spleen for eventual elimination from the
body, which will eventually determine the particle’s longevity in circulation and
clearance rate from the body [ 29 , 36 ]. The fates of foreign nanoparticles and their
hybrid nanoconstructs in vivo depend upon their physico-biochemical properties,
including their size, shape, and surface chemistry. Some novel approaches have
Fig. 2.7 Plasmon-resonant gold nanoparticles in biomedical applications: (a) colloidal gold
nanoparticles; (b) gold nanorods (GNR) [ 85 ]; (c) gold nanoshells (GNS) [ 86 , 87 ]; (d) golden car-
bon nanotubes (GNT) [ 33 ]; (e) bioconjugation of gold nanoparticles using GNR as an example
[ 88 ]. Scale bars represent: 10 nm (a), 100 nm (b), 300 nm (c), and 100 nm (d). Adapted from the
data of the cited articles by permission from American Chemical Society, Biomedical Engineering
Society, Wiley, Nature Publishing Group, and American Scientific Publishers. Note that some of
original images were amended by cropping, re-coloring, and rotating them
H.A. Jensen et al.