Application of Nanotechnology in Diagnosis and Therapeutics
427
phase to treat PPHG (Joshi et al. 2006). Current dosage of insulin comprises four
subcutaneous injections per day, which only reduce the serum glucose levels. This
therapeutic regimen fails to deliver the insulin in physiological pattern. Insulin is
injected from outside in proper dosage. Oral administration of insulin is a challenge
due to gastric enzymes which are potent to degrade the insulin. AuNPs are biocompatible and nontoxic in nature hence insulin is loaded on the gold NPs. This gives a
sustained release of insulin in the body and helps in the treatment of PPHG.
AuNPs are used as the labels in diagnostics and detection. They are extensively
used in the lateral flow devices and immunoassays. Lateral flow devices are very
popular among the user stem because of its low cost manufacturing and simplicity
that allows nonspecialized users to perform complicated tests easily. It is formed of
white porous membrane striped with a line of antibodies or antigen and interfaced
with antibodies conjugated with labels which are generally of gold nanoparticles that
is used for the detection of low molecular weight targets (Wilson 2008). AuNP have
a tremendous use in “bio-barcode assay”. This ultrasensitive assay is vigorously used
for detecting target proteins and nucleic acids. The principle of “Bio-barcode assay”
utilizes conjugated gold NPs with two barcodes oligonucleotides and target specific
antibodies and magnetic micro-nanoparticles functionalized with monoclonal antibodies. A large amount of barcode oligonucleotides are released upon detection of
target molecule. It provides identification and quantification of the target molecules.
Prostate-specific antigen (PSA) can be detected by this method with the detection
limit of 330 fg/ml given by Mirkin et al. (Wilson 2008).
There is a passive role of AuNPs in the imaging and detection but it has an active
role in sensing. It is preferentially used in the optical sensors. The surface Plasmon
resonance of the gold NPs is greatly helpful in optical sensors. There is a dramatic
influence of inter-AuNPs distance on the Plasmon resonance, when this distance is
reduced to less than the AuNPs diameter; it is the important factor in the sensor application of the AuNPs. The biological analyte linked with AuNPs results in the color
change that makes the basis of the sensing. This principle is pioneered by Leuvering.
Its sensitivity has been improved by using hyper-Rayleigh scattering, a differential
light-scattering spectroscopy (DLSS) (Boisselier and Astruc 2009). These are extensively utilized in electrochemical biosensors. In electrochemical bioassays, AuNPs
are used to connect the enzymes to the electrode surfaces. They mediate electrochemical reactions as the redox catalyst and helps in amplification of recognition signals for
biological processes. A wire of gold NPs is formed which connects the electrode and
the reaction center in the enzyme. The conducting tunnel of AuNPs serves in electron
transferring. Thus, the NPs attached to enzymes, for example, glucose oxidase acts as
the nanoelectrodes so that the turnover rate of electrons transferred can reach to 5000
which is seven times higher turnover rate of electron transfer from the active site of
glucose oxidase to oxygen (Boisselier and Astruc 2009). Example for immunosensor
is hepatitis B surface antigen determination kit. It carries multilayer films of negatively charged AuNPs/positively charged tris(2, ´
2-bipyridyl)cobalt(III) assembled on
platinum electrode surface covered with a layer of plasma-polymerized Nafion film.
DNA electrochemical sensing contains AuNPs modified with thiol-functionalized
oligonucleotides submitted to hybridization of the target DNA sequence. The basic
427
phase to treat PPHG (Joshi et al. 2006). Current dosage of insulin comprises four
subcutaneous injections per day, which only reduce the serum glucose levels. This
therapeutic regimen fails to deliver the insulin in physiological pattern. Insulin is
injected from outside in proper dosage. Oral administration of insulin is a challenge
due to gastric enzymes which are potent to degrade the insulin. AuNPs are biocompatible and nontoxic in nature hence insulin is loaded on the gold NPs. This gives a
sustained release of insulin in the body and helps in the treatment of PPHG.
AuNPs are used as the labels in diagnostics and detection. They are extensively
used in the lateral flow devices and immunoassays. Lateral flow devices are very
popular among the user stem because of its low cost manufacturing and simplicity
that allows nonspecialized users to perform complicated tests easily. It is formed of
white porous membrane striped with a line of antibodies or antigen and interfaced
with antibodies conjugated with labels which are generally of gold nanoparticles that
is used for the detection of low molecular weight targets (Wilson 2008). AuNP have
a tremendous use in “bio-barcode assay”. This ultrasensitive assay is vigorously used
for detecting target proteins and nucleic acids. The principle of “Bio-barcode assay”
utilizes conjugated gold NPs with two barcodes oligonucleotides and target specific
antibodies and magnetic micro-nanoparticles functionalized with monoclonal antibodies. A large amount of barcode oligonucleotides are released upon detection of
target molecule. It provides identification and quantification of the target molecules.
Prostate-specific antigen (PSA) can be detected by this method with the detection
limit of 330 fg/ml given by Mirkin et al. (Wilson 2008).
There is a passive role of AuNPs in the imaging and detection but it has an active
role in sensing. It is preferentially used in the optical sensors. The surface Plasmon
resonance of the gold NPs is greatly helpful in optical sensors. There is a dramatic
influence of inter-AuNPs distance on the Plasmon resonance, when this distance is
reduced to less than the AuNPs diameter; it is the important factor in the sensor application of the AuNPs. The biological analyte linked with AuNPs results in the color
change that makes the basis of the sensing. This principle is pioneered by Leuvering.
Its sensitivity has been improved by using hyper-Rayleigh scattering, a differential
light-scattering spectroscopy (DLSS) (Boisselier and Astruc 2009). These are extensively utilized in electrochemical biosensors. In electrochemical bioassays, AuNPs
are used to connect the enzymes to the electrode surfaces. They mediate electrochemical reactions as the redox catalyst and helps in amplification of recognition signals for
biological processes. A wire of gold NPs is formed which connects the electrode and
the reaction center in the enzyme. The conducting tunnel of AuNPs serves in electron
transferring. Thus, the NPs attached to enzymes, for example, glucose oxidase acts as
the nanoelectrodes so that the turnover rate of electrons transferred can reach to 5000
which is seven times higher turnover rate of electron transfer from the active site of
glucose oxidase to oxygen (Boisselier and Astruc 2009). Example for immunosensor
is hepatitis B surface antigen determination kit. It carries multilayer films of negatively charged AuNPs/positively charged tris(2, ´
2-bipyridyl)cobalt(III) assembled on
platinum electrode surface covered with a layer of plasma-polymerized Nafion film.
DNA electrochemical sensing contains AuNPs modified with thiol-functionalized
oligonucleotides submitted to hybridization of the target DNA sequence. The basic