Biomedical Engineering Reference
In-Depth Information
FIGURE 1.3
Schematic diagram of NMs and the surface modification to allow conjugation of var-
ious molecules of medical relevance (green sphere—fluorescent NMs; gray sphere—nonfluorescent
NM).
(For color version of this figure, the reader is referred to the online version of this topic)
and used in the preparation of water soluble NMs. The water-soluble NMs
that are now currently commercially available contain functional groups on
their surfaces making them easy to manipulate for various medical appli-
cations. Functional groups anchored to the surface of NMs during synthe-
sis or modification into their water soluble forms provide reactive sites for
subsequent bioconjugation reactions. These active functional groups often
involve sulfhydryl -SH, carboxyl -COOH, amine -NH
2
, hydroxyl -OH, and
others that allow attachment of biomolecules through various bioconjuga-
tion or crosslinking chemistry (
Figure 1.3
). Linkers for these NMs are car-
bodiimide, succinimide, maleidiimide, and bifunctional crosslinkers through
direct attachment (hydrophobic or electrostatic interactions) and sometimes
through biodin-avidin system. These various methods have their unique
qualities and applications along with inherent disadvantages, such as pos-
sible low yield and loss of functionality after conjugation, which researches
are actively studying to solve and improve. NMs that are found in biosen-
sors offer high sensitivity and high stability that are easier to use, faster,
and more inexpensive as compared with conventional diagnostics methods.
In addition, inexpensive instrumentation that accompanies these NM-based
biosensors are also currently being developed. These novel biosensors use the
small dimensions of NMs which allow their assembly into barcodes and high
density arrays to detect multiple analytes using miniature hand held sensing
devices that may only need light emitting diodes as power source.
Nanotechnology has also opened up new perspectives in the development
of biosensors that are applied to medicine, food, agriculture, industry, and envi-
ronmental monitoring. The nanotechnological innovations promise to improve
the sensitivity, accuracy, and flexibility for the analysis of chemical and bio-
chemical compounds. In addition, NMs allow a cost-effective production of
