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dhd997(金币+6, EPI+1): 热心啊 2011-05-08 13:04:36
Ultrasensitive DNA sequence detection
using nanoscale ZnO sensor arrays
Nitin Kumar, Adam Dorfman and Jong-in Hahm1
Department of Chemical Engineering, The Pennsylvania State University, 160 Fenske
Laboratory, University Park, PA 16802, USA
E-mail: jhahm@engr.psu.edu
Received 21 February 2006
Published 26 May 2006
Online at stacks.iop.org/Nano/17/2875
Abstract
We report that engineered nanoscale zinc oxide structures can be effectively
used for the identification of the biothreat agent, Bacillus anthracis by
successfully discriminating its DNA sequence from other genetically related
species. We explore both covalent and non-covalent linking schemes in order
to couple probe DNA strands to the zinc oxide nanostructures. Hybridization
reactions are performed with various concentrations of target DNA strands
whose sequence is unique to Bacillus anthracis. The use of zinc oxide
nanomaterials greatly enhances the fluorescence signal collected after
carrying out duplex formation reaction. Specifically, the covalent strategy
allows detection of the target species at sample concentrations at a level as
low as a few femtomolar as compared to the detection sensitivity in the tens
of nanomolar range when using the non-covalent scheme. The presence of
the underlying zinc oxide nanomaterials is critical in achieving increased
fluorescence detection of hybridized DNA and, therefore, accomplishing
rapid and extremely sensitive identification of the biothreat agent. We also
demonstrate the easy integration potential of nanoscale zinc oxide into high
density arrays by using various types of zinc oxide sensor prototypes in the
DNA sequence detection. When combined with conventional automatic
sample handling apparatus and computerized fluorescence detection
equipment, our approach can greatly promote the use of zinc oxide
nanomaterials as signal enhancing platforms for rapid, multiplexed,
high-throughput, highly sensitive, DNA sensor arrays.
DNA sequence analysis is widely applied to the areas of
mapping genes, determining genetic variations, detecting
genetic diseases, and identifying pathogenic micro-organisms.
The rapidly increasing numbers of sequencing data have
revealed a large number of single nucleotide polymorphisms
and other mutations in the human genome and in the
genomes of other organisms [1–5]. Subtle differences
in DNA sequence due to these polymorphic sites can
lead to considerable changes in disease susceptibility and
drug response in humans [1, 2, 6–8]. Similarly, small
disparity in genetic code can cause significant variations
in phenotypes and biological activities of micro-organisms.
Therefore, the development of improved DNA sequencing
technologies is critical in correlating specific DNA sequences
1 Author to whom any correspondence should be addressed.
with the particular biological function of an organism. Novel
techniques which can perform rapid and accurate genetic
sequence analyses on a large scale are specially warranted
as the need for fast, inexpensive, ultrasensitive, and highthroughput
DNA detection escalates in the areas of medicine,
public health, forensic studies, and national security.
Biomolecular fluorescence is the most widely used
detection mechanism in both laboratory-scale and highthroughput
genomics research. Fluorescence detection is the
dominant mechanism and extensively utilized in state-of-theart
DNA sensors such as DNA arrays and gene chips [5–12].
The emerging need for high-throughput genetic detection will
continue to push the limit of fluorescence detection sensitivity.
These sequencing assays require the use of lower DNA
concentrations as well as smaller amounts of fluorophores in
order to cope better with the increasing demands for effectively
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