Definition:
Nanomaterial utilizes
nanoscale engineering and system integration of existing materials to develop
better materials and products. Applications of nanomaterials have made their
presence strongly felt in various areas like healthcare, implants, and
prostheses; smart textiles, energy generation and conservation with energy
generating materials and highly efficient batteries, defence, security,
terrorism, and surveillance.
Bionanomaterial’s research has emerged as a
new exciting field, recognized as a new interdisciplinary frontier in the field
of life science and material science. Great advances in nanobiochip materials,
nanoscale biomimetic materials, nanomotors, nanocomposite materials, interface
biomaterials, nanobiosensors, and nano-drug-delivery systems have the enormous
prospect in industrial, defense, and clinical medicine applications.
Biomolecules assume the very
important role in nanoscience and nanotechnology, for example, peptide nucleic
acids (PNAs) replace DNA, act as a biomolecular tool/probe in the molecular
genetics, diagnostics, cytogenetics, and have enormous potentials in
pharmaceutics for the development of biosensors. Biosensor consists of a
biosensing material and a transducer that can be used for detection of
biological and chemical agents. Biosensing materials, like enzymes, antibodies,
nucleic acid probes, cells, tissues, and organelles, selectively recognize the
target analytes, whereas transducers like electrochemical, optical,
piezoelectric, thermal, and magnetic devices can quantitatively monitor the
biochemical reactions.
Nanoparticles
in Biosensing:
The sensitivity and
performance of devices are being improved using nanomaterials. Nanomaterials
with at least one of their dimensions ranging in scale from 1 to 100nm display
unique and remarkably different property as compared to its bulk because their nanometer size gives rise to high reactivity and
other enhanced beneficial physical properties (electrical, electrochemical,
optical, and magnetic) owing to nonlinearity after crossing the performance
barrier threshold.
Their applications can potentially translate into new assays
that improve upon the existing methods of biomolecular detection. Nanoparticles
have been widely used in biosensors for detection of nucleic acids, peptide
nucleic acid, and proteins. The enhancement in redox properties of gold
nanoparticles coupled with silver has led to their widespread application as
electrochemical labels in biosensor development with remarkable sensitivity.
The gold nanoparticles coated
with ferrocenyl hexanethiol and streptavidin were used to monitor the DNA
hybridization. Nanoparticles have also coupled with magnetic particles to
capture target DNA, which then hybridizes with a secondary probe DNA tagged to
metal nanoparticle and detected by anodic stripping voltammetry. A common
problem with silver enhancement is a high background signal resulting from
nonspecific precipitation of silver onto the substrate electrode and to
overcome the setback, various electrode surface treatments and
electrochemically or enzymatically controlled deposition methods of silver have
reported. For reducing the silver related background signal and increasing the
sensitivity, a new system of electrochemical detection of DNA hybridization
based on stripping voltammetry of enzymatically deposited silver has developed.
The target DNA and a biotinylated DNA immobilized probe hybridize to a capture
DNA probe tethered onto a gold electrode. NeutrAvidin- (NA-) conjugated
alkaline phosphatase binds to the biotin of the detection probe on the
electrode surface converting the nonelectroactive substrate to a reducing
agent. The latter reduces the metal ions in solutions leading to the deposition
of metal onto the electrode surface and DNA backbone.
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