Biomedical Engineering Reference
In-Depth Information
Filters
200 μm
a
Pore
Reservoir
Electrodes
b
c
d
τ
2
τ
3
τ
1
Time
Time
Time
Specific protein-
protein interactions
No protein-protein
interactions
Nonspecific protein-
protein Interactions
FIGURE 5.29
A.Coulter.counter.for.screening.cancer.cells..(From.Andrea.Carbonaro,.Swomitra.K..
Mohanty,.Haiyan.Huang,.Lucy.A..Godley,.and.Lydia.L..Sohn,.“Cell.characterization.using.a.protein-
functionalized.pore,”.
Lab Chip
.8,.1478-1485,.2008..Reproduced.with.permission.from.The.Royal.
Society.of.Chemistry.)
of whether it is cancerous or not). When cancer cells bearing the CD34 protein on their surface
were passed through the antibody-functionalized pore, they spent on average 4 ms more transit
time than normal cells or than cancer cells through an uncoated pore. In principle, this tool
could be interfaced downstream with a sorter to select the CD34
+
cells for analysis.
5.3.8 Trapping and Culturing Microfabricated Cell Assemblies
In many tissue engineering, biotechnology, and cell biology applications, the ability to
produce, culture, and manipulate
assemblies
of cells (rather than single cells) is desirable
because many cell types do not grow well unless they “feel the company” of their kin. his
“companionship” is signaled to them through secretion of growth factors that have an efect
only when they reach a certain concentration threshold, so cell density (and time) plays
an important role in the local accumulation of growth factors. Nancy Allbritton's group
from the University of North Carolina has devised a method to produce small, transferrable
units of solid cell culture substrates that support cell attachment and culture (
Figure 5.30
).
hese (~100 μm-side square) “rats,” which can be micromolded in a number of biocompat-
ible polymers (such as polystyrene or epoxy) from a PDMS template, can be mechanically
released from their template by a pin and transferred onto a diferent substrate to amplify
the cell culture.
