Biomedical Engineering Reference
In-Depth Information
AuNPs have been used as biosensors in living whole cells using SPR scatter-
ing images and SPR absorption spectra.
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The sensor involved colloidal AuNPs
and AuNPs conjugated to monoclonal anti-epidermal growth factor receptor
(anti-EGFR) antibodies that were incubated with a nonmalignant epithelial cell
line (HaCaT) and two malignant oral epithelial cell lines (HOC 313 clone 8 and
HSC 3). The colloidal AuNPs were found in dispersed and aggregated forms
within the cell cytoplasm that provided anatomic labeling information, but their
uptake was nonspecific for malignant cells. On the other hand, the anti-EGFR
antibody conjugated NPs specifically and homogeneously bound to the surface
of cancer cells with 600% greater affinity than to the noncancerous cells. This
specific and homogeneous binding to the cancerous cells produced a relatively
sharper SPR absorption band with a red shifted maximum compared with the
noncancerous cells. These SPR scattering imaging or SPR absorption spectros-
copy can be used for molecular diagnosis and investigation of oral epithelial
living cancer cells in vivo and in vitro.
A diagnostic magnetic resonance sensor that combined a miniaturized nuclear
magnetic resonance (NMR), probe with targeted MNPs for detection and molec-
ular profiling of cancer cells was reported.
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The sensor was used to measure the
transverse relaxation rate of water molecules in target cells which were labeled
with magnetic NPs. The sensor achieved sensitivity improvements by synthesiz-
ing new NPs with higher transverse relaxivity at the optimized assay protocols.
The nanobiosensor detected as few as two cancer cells in 1-µL sample volumes
of unprocessed fine-needle aspirates of tumors and profiled the expression of
several cellular markers in <15 min.
Semiconductor QDs have been used to detect whole cancer cells that over-
express HER2, a surface coating protein that is found in breast cancer cell line
SK-BR3.
6,11,12,41,70
Carboxyl functionalized CdSe/ZnS emitting at 620 and/or
530 nm were covalently conjugated with antibodies against HER2 and exposed to
suspended or adherent SK-BR3 cells. Suspended cells were mounted on glass slides
before taking microscope images using a UV light source. The results indicated that
the fluorescent cancer cells were detected more easily and over a longer time frame
than cells that were stained with antibodies conjugated with organic dye.
4.8.4 Procedure for QD-Based Detection of Breast Cancer Cells
The following protocol was adopted from a paper published by Xu et al.
12
In
this paper, a QD-based sensor using silanized glass slide as the capture surface
successfully detected breast cancer cells.
A. Grow the cells
(1)
Human breast cancer cell line (SK-BR3) that overexpress HER2.
171,172
is
used as a model for the development of the QD-based whole-cell imag-
ing sensor. The cell line SK-BR3 (American Type Culture Collection,
Manassas, VA) is grown in RPMI-1640 medium supplemented with 10%
