Biomedical Engineering Reference
In-Depth Information
Fig. 1.1 (a) Transmission Electron Microscope (TEM) image of a 7 nm Al
2
O
3
nanopore
(b) Nanopore fluidic setup showing Si nanopore chip encapsulated between two chambers of a
PMMA flow cell filled with conductive electrolyte (c) Schematic of DNA transport through a
nanopore (d) Characteristic downward current blockades seen during the transport of individual
DNA molecules through the pore (Inset) Current signature corresponding to a single DNA translo-
cation event showing, blockage ratio I
B
, and translocation time, t
D
, specific to the translocation event
detection of single nucleotide polymorphisms (SNP's) with application to cancer
diagnostics [
36
], stretching transitions in individual dsDNA [
31
], unzipping kinetics
of hairpin DNA molecules [
59
], DNA sizing and sieving [
85
], and the detection of
DNA-protein complexes essential in DNA repair [
80
].
1.2 Nanopores in Biology
The biological cell contains various types of nanopores and nanochannels that
regulate the flow of ions and molecules into and out of the cell. These nanopores
play a vital role in cellular processes such as intercellular communication and
signaling between subcellular structures. Examples include gated, selective ion
channels that connect the cell cytosol to the cell exterior; nuclear membrane
pores that control the passage of biomolecules such as messenger RNA (mRNA)
from the cell nucleus into the cytosol; proteins that are secreted across pores in the
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