DNA is the genetic material of human and numerous other species closely
relevant to our health. It is thus a central material to biosensing, which is
the basis for disease diagnosis, prognosis, and treatment. Although various DNA
biosensing techniques have been developed, the demand for higher throughput and
sensitivity methods is ever increasing. Nanotechnology offers great potential to
meet the need by providing unprecedented tools that can precisely detect,
manipulate, and assemble DNA.
DNA, also referred to as
deoxyribonucleic acid is the molecules inside cells that carry genetic
information and pass it from one generation to the next.
An ability to retrieve genetic information from single DNA molecules promises
to significantly enrich our understanding of many critical biological and
pathological processes. Molecular Combing is a technique that can stretch and
immobilize genome DNA on a solid surface for single molecule analysis. However,
conventional Molecular Combing technique can only generate randomly distributed
DNA chains that are not suitable for large scale and automated data acquisition.
Jingjiao Guan and his colleagues from the Integrative NanoScience
Institute have developed an approach capable of stretching and patterning
DNA molecules into large arrays with each DNA chains precisely positioned and
aligned. This technique holds potential to become a new platform for analysis of
single DNA in a large-scale and automated fashion.
Fluorescence image of an array of stretched
Not only a biomolecule, DNA is also a nanomaterial with a unique set of
structures and properties such as high length-to-width ratio, double helical
structure, base pairing ability, and sequence-specific interactions with other
molecules. DNA has thus been used to construct nanowires, which are widely
regarded as a new class of biosensing structures.
To build a functional sensor, nanowires typically need to be precisely
assembled into a designed architecture. Lack of robust and low-cost techniques
for nanowire assembly is currently hindering the advance of this field.
Jingjiao Guan and his colleagues have developed a method for generating
arrays of DNA-based nanowires. Compared to others, this method is robust,
inexpensive, and intrinsically capable of generating highly-ordered over a large
area. It also allows functionalization of the nanowires by various methods such
as surface coating by vapor deposition, chemical conjugation, and physical
entrapment of nanoparticles.
Fluorescence image of an array of DNA (green)
nanowires embedded with fluorescent nanocrystal quantum dots
Nanochannels constitute another class of nanostructures for next-generation
biosensing. They have been demonstrated with unique advantages for probing
single DNA dynamics, detecting DNA-protein interactions, mapping genes on single
DNA molecules, and separating DNA of different sizes. However, advance of this
nanochannel-based biosensing is also hindered by the lack of inexpensive,
simple, and reliable approaches for fabricating the nanostructures and
integrating them into functional devices.
Jingjiao Guan and his colleagues have developed a technique capable of
producing a large array of nanochannels by using the DNA nanowires as templates.
This method promises to be used to construct low cost, parallel, and
high-throughput sensors for linear analysis of single chromosomal DNA.
Scanning Electron Micrograph of a nanochannel
converted from a DNA nanowire
Jingjiao Guan, L. James Lee, Generating highly ordered DNA nanostrand arrays.
Proc Natl Acad Sci U S A. 2005, 102, (51), 18321-18325.
Jingjiao Guan, Bo Yu,
L. James Lee, Forming highly ordered arrays of functionalized polymer nanowires
by dewetting on micropillars. Adv Mater. 2007, 19, (9), 1212-1217.
Guan, Nick Ferrell, Bo Yu, Derek Hansford, L. James Lee, Simultaneous generation
of hybrid Arrays of micro/nanoparticles and nanowires by dewetting on
micropillars. Soft Matter. 2007, 3, 1369-1371.
C. H. Lin, J. Guan, S. W.
Chau, L. J. Lee, Experimental and numerical analysis of DNA nanostrand array
formation by molecular combing on microwell-patterned surface. J Phys D: Appl
Phys. 2009, 42, (2), 025303.
Jingjiao Guan, Pouyan E. Boukany, Orin
Hemminger, Nan-Rong Chiou, Weibin Zha, Megan Cavanaugh, L. James Lee, Large
laterally ordered nanochannel/nanostrand arrays from DNA combing and imprinting,
Copyright AZoNano.com, Professor Jingjjiao Guan (Integrative
NanoScience Institute, Florida State University)