Biomedical Engineering Reference
In-Depth Information
of non-specifi cally captured target proteins can be analyzed by mass spectrometry.
The comparison of two MS datasets generated from two different samples immedi-
ately identifi es the differentially expressed proteins by their molecular mass. In some
cases the differentially displayed proteins might be identifi ed immediately on the basis
of their molecular weights. These protein markers mostly need to identify separately.
Analyte proteins are enriched by affi nity chromatography, which can easily be achieved
using the same adsorptive material as used for the SELDI experiment. The enriched
proteins can then be identifi ed by standard methods. The SELDI technology is easy to
handle and suitable for the fast detection of differences in total protein content of dif-
ferent samples. Since the detector sensitivity of time-of-fl ight mass analyzers decreases
with increasing molecular weights, SELDI is perfectly suited for the detection of small
proteins and peptides but exhibits limitations with respect to high molecular-weight
proteins or membrane proteins [67]. Although assay sensitivity in SELDI experiments
is much lower in comparison to sandwich immunoassays, the SELDI approach is still
a quick screening platform for any unknown protein biomarker. Compared with
fl uorescence-based microarrays, the current focus for SELDI biochips continues to
increase surface selectivity through the development of new surface affi nity legends,
reduce non-specifi c binding, and improve immobilization effi ciencies. With improved
surfaces combined with advances in mass spectrometry instrumentation and methodol-
ogy, SELDI could be a great proteomic tool in understanding biological functions.
11.3.3 Protein chip applications
The protein chip technology has become a powerful tool for large-scale and high
throughput biology. Further advances in this fi eld will lead to convergence of the
physical, chemical, and biological sciences with crucial impact on biotechnology and
improving quality of life. Adoption of a protein chip concept to understand the global
expression profi le and detection of proteins in different physiological states will accel-
erate better understanding of biology and disease mechanisms that can lead to more
effective therapeutic strategies. The protein chip is mainly used in biomedical and phar-
maceutical applications. The protein chip accelerates pharmaceutical research for new
drug protein targets identifi cation in transformed cell lines or diseased tissues. The vali-
dation of the detected targets, in-vitro and in-vivo toxicology studies, and checks for
side effects can be performed with this approach. Clinical researchers can use the chip
to compare normal vs disease samples, disease vs treated samples, fi nd molecular mark-
ers in body fl uids for diagnosis, monitor diseases and their treatments, and determine
and characterize post-translational modifi cations. In clinical chemistry it would be inter-
esting to subtype individuals to predict response to therapy. The great potential of the
protein chip in basic research, diagnostics, and drug discovery has been demonstrated.
11.3.3.1 Basic research
The use of biochips in basic biological research has provided information that was
heretofore inaccessible. Protein chips, especially functional microarrays, are used to
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