Biomedical Engineering Reference
In-Depth Information
Chapter 5
Solid State Nanopores for Selective Sensing
of DNA
Waseem Asghar, Joseph A. Billo, and Samir M. Iqbal
Abstract This chapter focuses on the functionalized solid state nanopores for
the purpose of rapidly and accurately sensing specific sequence of DNA. Fabrica-
tion processes are described, consisting of standard photolithography followed
by using either a transmission electron microscope or a plasma polymer film to
create and shrink the nanopore. The molecular dynamics of DNA-nanopore inter-
actions are also discussed. Smaller pore diameter results in slower translocation of
DNA through the nanopore, but increases van der waals force on the DNA and
decreases the ionic current. Increase in applied voltage decreases the van der Waals
force while increasing the ionic current and translocation velocity. Chemical
functionalization of nanopores is then discussed. This allows a nanopore to be
selective with translocating specific DNA sequence. This is done by modifying
the surface in an attempt to control its surface charges and hydrophobicity. Probe
DNA is used to functionalize the pore and achieve selectivity. In terms of sensing,
perfect complementary DNA translocates faster than single-base-mismatch DNA.
The flux can be measured from the current pulses when the translocating DNA
blocks the nanopore under applied voltage.
Keywords Biosensors • Selective sensing • Functionalization • Pulsed plasma
polyerization • Surface composition • Molecular dynamics • Van der waals force
• Translocation velocity • Self-assembled monolayer • Single base mismatch •
Nucleotide polymorphism • Hairpin loop DNA • Electrochemical signals
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