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Unformatted text preview: e areas, and in fact
many of the developments in one category
catalyze development in another.
Bioanalysis. The earliest commercial nanotechnology is atomic force microscopy,
now known more generally as scanning
probe microscopy (SPM). Using a siliconbased needle of atomic sharpness, this
approach was first used to image the topography of surfaces with atomic-scale precision2. The probe, positioned so close to the
surface that it interacts with the atoms as it
scans the surface, can also be used to pick
atoms up and move them around for bottom up nanoscale assembly (Box 2). The
technology thus provides an accessible
benchtop device for nanoscale engineering
Although SPM is used primarily for analytical research, several companies have
automated it for read-write capabilities
(Table 2). NanoInk (Chicago, IL, USA) and VOLUME 21 NUMBER 10 OCTOBER 2003 N ATURE BIOTECHNOLOGY F E AT U R E © 2003 Nature Publishing Group http://www.nature.com/naturebiotechnology Core Interior Surface
Figure 2 Dendrimer architecture in two and three dimensions. A dendrimer can be defined into a
multitude of structures by tuning the three architectural components: the core (yellow), the interior area
containing branch upon branch of repeat units (blue) and an exterior surface of terminal moieties
attached to the outermost generation (red.) Source: Dendritic Nanotechnologies BioForce Nanosciences (Ames, IA, USA) are
creating truly nanoscale molecular arrays
using SPM tools to print biomolecular array
elements. Because the instrument has both
print and read capability, these systems do
not require molecular labeling for ultrahighthroughput bioanalysis.
Some micron-scale technologies can be
considered platforms for nanoscale bioanalysis, and these products have already
proven their value in the marketplace. For
example, Caliper Technologies’ (Mountain
View, CA, USA) microfluidic systems rou- tinely transport nanoliter volumes of fluid
for nucleic acid and protein analysis.
Affymetrix’s and Nanogen’s (San Diego, CA,
USA) microarray platforms manipulate subnanogram quantities of genetic material.
These technologies are converging to submicron resolution because of the demand for
increased sensitivity and throughput for
genomics and proteomics. Nanomaterials
and true nanoscale devices are also being
developed to address the need for greater
sensitivity in high throughput screening
(Box 3). Nanoparticles (dots, bars, dendrimers or
colloids) provide molecular labels that are
highly stable, readily multiplexed and comparable in size to the molecular components
of interest. Quantum dots leverage semiconductor materials to provide robust quantum
‘fluorescence,’ with an array of colors that
requires only a single illumination source.
Quantum dots with a variety of conjugates
and colors are currently available from
Quantum Dot (Hayward, CA, USA) and
Evident Technologies (Troy, NY, USA).
Nanobars, constructed from alternating
layers of reflective metals, are curr...
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This document was uploaded on 09/24/2013.
- Fall '13