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For example, different proteins such as antibodies, antigens, and enzymes can be
immobilized within protein biochips. Protein microarrays are reliable tools for detec-
tion of multiple biomarkers with only a minimal quantity of sample and have enor-
mous potential in applications for personalized medicine (Yu et al. 2010 ).
Microfl uidics
Microfl uidics is the special behavior of fl uids fl owing in channels the size of
a human hair. Fluids in this environment show very different properties than
in the macro world. This new fi eld of technology was enabled by advances in
microfabrication – the etching of silicon to create very small features. Microfl uidics
is one of the most important innovations of biochip technology. Microfl uidics allows
the reduction in size with a corresponding increase in the throughput of handling,
processing and analyzing the sample. Other advantages of microfl uidics include
increased reaction rates, enhanced detection sensitivity and control of adverse
events. Applications of microfl uidics, in relation to molecular diagnostics, include
the following:
- Genomic analyses
- Protein analysis
- Gene expression and differential display analysis
Several commercial microfl uidic technologies are available and a few examples
are described in the following text.
Fish-on-Chip
Although interphase FISH is a sensitive diagnostic tool used for the detection of
alterations in the genome on cell-by-cell basis, the cost-per-test and the technical
complexity of current FISH protocols have limited its widespread utilization in
clinical settings. To address this situation, a microchip-based FISH protocol has
been devised and coupled with a novel method to immobilize peripheral blood
mononuclear cells inside microfl uidic channels (Sieben et al. 2007 ). These fi rst
on- chip implementations of FISH allow several chromosomal abnormalities asso-
ciated with multiple myeloma to be detected with a tenfold higher throughput and
one tenth the reagent consumption of the traditional slide-based method. Moreover,
the chip test is performed within hours whereas the conventional protocol required
days. In addition, two on-chip methods to enhance the hybridization aspects of
FISH have been examined: mechanical and electrokinetic pumping. Similar agita-
tion methods have led to signifi cant improvements in hybridization effi ciency with
DNA microarray work, but with this cell-based method the benefi ts were moderate.
2 Molecular Diagnostics in Personalized Medicine