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Cite this: Nanoscale, 2015, 7, 1596
Received 26th September 2014,
Accepted 26th October 2014
DOI: 10.1039/c4nr05638h
www.rsc.o rg/nanoscale
Targeted labeling of an early-stage tumor spheroid
in a chorioallantoic membrane model with
upconversion nanoparticles†
Kai Liu,‡
a,b,c
Jasmin A. Holz,‡
b
Yadan Ding,
b,c,d
Xiaomin Liu,
a
Youlin Zhang,
a
Langping Tu,
a
Xianggui Kong,*
a
Bram Priem,
b
Annemarie Nadort,
b
Saskia A. G. Lambrechts,
b
Maurice C. G. Aalders,*
b
Wybren Jan Buma,
c
Yichun Liu
d
and Hong Zhang*
c
In vivo detection of cancer at an early-stage, i.e. smaller than
2 mm, is a challenge in biomedicine. In this work target labeling of
an early-stage tumor spheroid (∼500 μm) is realized for the first
time in a chick embryo chorioallantoic membrane (CAM) model
with monoclonal antibody functionalized upconversion nanoparti-
cles (UCNPs-mAb).
In clinical oncology the detection of early-stage cancer like car-
cinoma in situ and tumors smaller than 2 mm is of great
importance for improving the cancer cure probability.
1–3
Unfortunately, most of the present clinical imaging modalities
like ultrasonic imaging, computed tomography (CT), and mag-
netic resonance imaging (MRI) are not sufficient for detecting
the early-stage cancers because of their low resolution and/or
poor sensitivity and/or specificity.
4,5
Fluorescence imaging has
recently regained increased attention for cancer diagnosis,
because of the new developments in exogenous luminescent
materials,
6–14
such as rare earth ion doped upconversion nano-
particles (UCNPs) that can efficiently convert near infrared
(NIR) light to visible and/or shorter wavelength NIR light. In
comparison with traditional “down conversion” fluorescent
markers that need ultra-violet or visible (UV-Vis) light for exci-
tation, the UCNPs hold many advantages for biomedical
imaging, such as minimized background fluorescence, and no
photo bleaching.
11–14
Furthermore, since UCNPs have a large
surface area, bio-functionalized molecules like folic acid, pep-
tides, photosensitizers, doxorubicin (DOX), and si-RNA can be
easily conjugated for multifunctional labeling or therapy.
Numerous research studies have been reported in this respect
on both in vitro and in vivo tests utilizing UCNPs.
15–25
For
example, Zhou et al. achieved tri-mode imaging of upconver-
sion luminescence, magnetic resonance and positron emission
tomography (PET) in mouse utilizing fluorine-18-labeled Gd
3+
/
Yb
3+
/Er
3+
co-doped NaYF
4
UCNPs.
23
However, these research
studies are performed on the mice model in which the
imaging is usually executed at a relatively late stage when
tumors reach 4–6 mm. In vivo target detection of early stage
cancer, i.e. smaller than 2 mm, remains a difficult task in
biomedicine.
In this work, target labeling of an early-stage tumor spher-
oid (∼500 μm) was realized for the first time in a chick embryo
chorioallantoic membrane (CAM) model with monoclonal
antibody functionalized upconversion nanoparticles (UCNPs-
mAb). An early-stage tumor spheroid model was built first by
transplanting an in vitro cultured 3 dimensional multicellular
tumor spheroid (MCTS) of human breast cancer cells MCF-7
onto the chick embryo CAM. The chick embryo CAM is a well-
established model which has already been widely used for
cancer and angiogenesis research, drug delivery, immunology
etc.
26–34
Compared with the widely used mice model, the chick
embryo CAM has unique advantages in cancer research,
including (i) the chick embryo is a naturally immunodeficient
system, and various heterogeneous tumor cells can be trans-
planted into the CAM without any species-specific restrictions,
and (ii) since the chick embryo CAM is an extremely thin mem-
brane layer (∼200 μm) that usually lies at the top, it is very con-
venient to observe the motility process of the injected cancer
cells or drug molecules under a microscope with little impact
on the host. On top of that, the chick embryo model is simple
† Electronic supplementary information (ESI) available: Details of experimental
procedures for the sample preparation and characterization, Chick CAM model,
3-D multicellular tumor spheroids, UCNPs circulating in CAM. See DOI: 10.1039/
c4nr05638h
‡ These authors contributed equally to this article.
a
State Key Laboratory of Luminescence and Application, Changchun Institute of
Optics, Fine Mechanics and Physics, Chinese Academy of Science, Changchun
130033, P. R. China. E-mail: xgkong14@ciomp.ac.cn
b
Department of Biomedical Engineering and Physics, Academic Medical Center,
University of Amsterdam, 1105 AZ Amsterdam, P.O. Box 22700, The Netherlands.
E-mail: m.c.aalders@amc.uva.nl
c
Van’tHoff Institute for Molecular Sciences, University of Amsterdam, Science Park
904, 1098 XH Amsterdam, The Netherlands. E-mail: h.zhang@uva.nl
d
Centre for Advanced Optoelectronic Functional Materials Research, Key Laboratory
for UV Light-Emitting Materials and Technology of the Ministry of Education,
Northeast Normal University, Changchun 130024, P. R. China
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