Biology Reference
In-Depth Information
increased sensitivity by combining conventional electrodes with
nanoparticles, nanowires, dendrimers, liposomes, or carbon nan-
otubes. The use of these nanoscale materials for electrochemical
DNA sensorsis discussed in the following sections.
14.2 Nanoparticle-Based Electrochemical DNA Detection
Nanoparticles can be synthesized in size ranges similar to many
common biomolecular markers. This trait makes nanoparticles
particularly well suited to interface with biomolecules and to make
hybrid systems. Typically, nanoparticles are prepared by chemical
methods such as decomposition of metal complexes or reduction
of metal ions. Capping agents are often used to stabilize the
nanoparticle, control the size distribution during growth, and also
provide functional groups to allow modification with a variety of
linking chemistries for tailor-made functionalities. The types of
metal nanoparticles typically used in sensing applications include
coinage and noble metal (gold, silver, iron, platinum, etc.) magnetic,
solid oxide, and semiconductor nanoparticles containing group II
or III elements (e.g., CdS, ZnS, InP). Metal-nanoparticle integration
intosensingschemesconsistsoftheiruseassupportstoimmobilize
DNAprobesontosurfacesandaselectrochemicallabelsbydetecting
their intrinsic atomic makeup (i.e., stripping voltammetry after
dissolution of the metal), or nonstripping methods that take
advantage of catalytic properties of the material.
14.2.1
Nanoparticle Modification of Electrodes and Their
Use as Supports for DNA Immobilization
Nanoparticles have been used extensively for the immobilization
of biomolecules [3]. In addition to their biocompatibility they can
produce a unique microenvironment that provides improvement
in the freedom of orientation for a
nity binding with advantages
over planar substrates, an increase in surface area for higher probe
loading capacities, and enhanced diffusion of amplification agents.
Modificationofelectrodesurfaceswithnanoparticlescanbecarried
outbysimpleelectrostaticadsorptionorcovalentattachmentssuch
