Nanotechnology-Enabled Sensors

452 Chapter 7: Organic Nanotechnology Enabled Sensors
Piezoelectric transducers can also be utilized along with the lock-andkey
capability of DNA strands to develop highly specific sensors. As described
in Chap. 3, Caruso et al were the one of the first groups who used
this ability with quartz crystal transducers. 86 They used both single-layer
and multilayer DNA. They monitored the DNA immobilization and the
hybridization of the immobilized DNAs in situ from the QCM) frequency
changes (Fig. 7.65). Equal frequency changes were observed for the DNA
immobilization and hybridization steps for the single-layer films, which
was an indication that the DNA probe-to-hybridized DNA target was in a
ratio of 1:1. The multilayered DNA films also exhibited DNA hybridization,
with a greater quantity of DNA hybridized compared with the singlelayer
films.
Fig. 7.65 The QCM frequency change versus time for the immobilization of biotinylated-DNA
from HEPES buffer onto an avidin-modified QCM electrode. The
arrow indicates the time at which the biotinylated-DNA was injected into the
HEPES solution. Reprinted with permission from the American Chemical Society
publications. 86
7.5.5 DNA-Protein Conjugate-based Sensors
DNA is a ready-made engineered material that can be employed for
sensing applications and as a building block for making nanosized
transducing platforms. Until researchers learn to intelligently control the
bottom-up synthesis of complex nanostructures, they have little choice but
to imitate biology, and use bio-components such as DNA and proteins
which can be put together on demand. The pool of knowledge about such
molecules allows researchers to execute their needs with control, precision