Biology Reference
In-Depth Information
5.1 Introduction
Various nanomaterials, including carbon nanotubes, nanoparticles,
nanomagnetic beads, and nanocomposites, are being used to
develop highly sensitive and robust biosensors and biosensing
systems [1] with a special emphasis on the development of
electrochemical-based(bio)sensors[2,3]duetotheirsimplicityand
cost e
ciency.
One of the main requirements for a good performance of
a biosensor is the high sensitivity of the response. This is of
great importance when, for example, it is required to use the
biosensor in clinical diagnostics for the detection of low levels of
clinical biomarkers in human fluids [4], because in most cases the
biomarker to be detected is present in very low concentrations. The
needforbiosensingsystemsthatcandetectthesemarkerswithhigh
sensitivity without loss of selectivity, that is, low detection limits
with high reliability and superior reproducibility, is becoming an
important challenge.
Theamplifieddetectionofbiorecognitioneventsandspecifically
of DNA hybridization events stands out of the biosensing field,
because it is one of the most important objectives of the current
bioanalytical chemistry. In this context, approaching the catalytic
properties of some (bio)materials appears to be a promising way to
enhance the sensitivityof the bioassays.
Catalystsarematerialsthatchangetherateofchemicalreactions
without being consumed in the process. Because of their huge
economicalcontribution,byloweringthecostsofseveralprocesses,
they are actually one of most wanted materials and can be found in
manufacturing processes, fuel cells, combustion devices, pollution
control systems, food processing, and sensor systems. Catalysts are
generally prepared from transition metals, most of them from the
platinum group, but this fact still represents a high cost due to the
materialexpensiveness,andthusareductioninusedamountswould
beappreciated [5, 6].
The coupling of enzymes as biocatalytic amplifying labels is a
generated paradigm in developing bioelectronic sensing devices.
The biocatalytic generation of a redox product upon binding of
the label to the recognition event, the incorporation of redox
