الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Metal nanoparticles have a great importance in Photoacoustic
imaging (PAI) technique and in Surface enhanced Raman
Spectroscopy (SERS). The size effect of gold nanospheres
(AuNSs) used as a contrast agent for the PAI of breast cancer cell
line MDA-MB 231 have been assessed. The decrease in the
AuNS size, at the same optical density (OD), results in an
improved PA signal, due to the increase in the total surface area
of the particles resulting in more heating. The PA signal generally
increases linearly with increasing OD, with almost the same rate
of increase for the three used particle sizes. It is observed that
PEGylation of AuNPs, as contrast agent, diminishes the PA
images of cancer cells due to their increased resistance to uptake
the AuNP, which results in diminishing the PA image compared
to the image obtained for cells incubated with unPEGylated
AuNSs. An enhanced PA image contrast is obtained for cells
loaded with silica coated Gold nanorods (AuNRs) as compared to
cells loaded with PEGylated AuNRs. This is because of the
enhanced cellular uptake for Silica coated AuNRs and the
decrease of the interfacial thermal impedance between gold and
surrounding solvent, which allows the particle to generate more
heat to the environment and hence increase the PA signal.
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Surface Enhanced Raman Spectroscopy (SERS) of fibrinogen,
adsorbed on label-free biosensors electroplated with gold film,
was studied as a function of the thickness of the electroplated
gold film. The biosensors are composed of arrays of SiO2
nanospheres (of diameters ~500 nm) core with gold nanoparticle
seeding (~4 nm) shell and an additional varying thickness gold
electroplated films. The extinction spectra of these arrays show
multiple extinction peaks resulting from the interference of beams
reflected between the flat substrate and the surface of the
dielectric spheres. There is an increase in the peaks intensity and a
red shift with increasing plating time of the gold film. The
sensitivity of these biosensors, to the adsorption of fibrinogen was
measured, as a function of gold film plating time, where the
extinction peaks shifts more toward the red. SERS of fibrinogen
on these biosensors shows an increase in the fibrinogen Raman
bands with the increase of electroplating up to a surface
roughness of mean value ~1.35 nm (as measured by scanning
tunneling microscopy (STM)). Further increase, in electroplating,
results in a decrease in the intensity of the peaks. Similar SERS
results were obtained for the cresyl violet (CV) dye adsorbed on
these biosensors. These changes in the sensitivity are explained in
terms of interplay of the surface field enhancement due to the
growth in the nanoparticles size and the resulting possible hotspot
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effects, and the reduction in the enhancement of the field due to
the increase in the metal shell thickness.
The enhancement effect of silver nanoparticles (AgNPs), to the
SERS in the detection of single nucleotide mutated synthetic
deoxyribonucleic acid (DNA) of Kirsten rat sarcoma (KRAS)
gene is studied. This technique shows the effective use of SERS
for the early detection of cancer. This technique provides low
coast sensitive way to differentiate mutated DNA from normal
ones, with minimal sample preparation. The SERS is able to
detect very low concentration of mutated DNA down 9x10-9M,
which is very sensitive enough for the early detection of cancer.