Biomedical Engineering Reference
In-Depth Information
(a)
1
2
Time
Time
FIGURE 1.55
(a) Schematic for a biosensor based upon Si
nanowire detection of single viruses via immobi-
lized antibodies. Two nanowires are shown each
with a different immobilized antibody. Nanowire
1 contains anti-influenza type A antibody, and
nanowire 2 contains antiadenovirus group III
antibody. The temporal signal response to the
binding of an adenovirus and its subsequent
release is shown to the right. (b) Si nanowires 1
and 2 outputs are shown. The vertical black
arrows correspond to the times of addition of: 1,
adenovirus; 2, influenza A virus; 3, pure buffer;
and 4, 1:1 mixture of adenovirus and influenza A
virus. Smaller arrows indicate lower intensity
short-duration conductance changes due to virus
particles passing by the Si nanowire but not bind-
ing to antibody. Reprinted from Patolsky, F,
Zheng, G., Hayden, O., Lakadamyali, M.,
Zhuang, X., Lieber, C.M. (2004). Electrical
Detection of Single Viruses.
Proc. Natl. Acad. Sci.
USA
101:14017-14022. With permission of
Elsevier Publishing and National Academy of
Sciences (2004) copyright.
Time
(b)
1
2
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4
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1
975
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925
2
900
0
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3200
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reduced by H
2
O
2
, the nanotube luminescence is restored. Therefore, glucose oxidase catalysis
of increasing glucose concentrations to form increasing H
2
O
2
product results in an increasing
luminescence signal (186). This nanoscale biosensor allows sensitive detection of glucose
down to 35 pM. An additional advantage is that the near IR optical signal (994 nm emission
max.) may be detectable in vivo up to centimeters below the skin. In this wavelength region,
human tissue and biological fluids such as blood are particularly transparent. Aside from the
progress being made in nanoscale biosensors and in increasing the sensitivity of different sig-
nal transduction mechanisms, new immobilization strategies are being developed to couple
ever more specific and sensitive biological components to the biosensor platforms. Some
involve creative innovations in microfabrication through surface-based self-assembly methods
following specific chemical or adsorptive treatments of the surface (187,188).
To achieve miniaturization of feature sizes to the nanoscale on a biosensor platform for
commercial applications the current methods employed in the research laboratory must be
evolved to incorporate new and rapid manufacturing processes allowing
nanomanufacturing of platforms. At the University of Massachusetts Lowell, we and two
partner institutions (University of New Hampshire and Northeastern University) have
