260
S. E. H. Murph and E. Searles
Iron Oxide–Gold Rods Multifunctional Nanoparticle Synthesis
Gold nanorods were attached to iron oxide through electrostatic interactions. Gold
rods synthesized with cetyltrimethylammonium bromide (CTAB) using the method
previously used in the Murph’s laboratory were used [17]. Iron oxide was treated
with chloroauric acid to ensure the particles preserved a negative surface charge.
The 0.5 mM iron oxide nanospheres, 0.05 M chloroauric acid, and concentrated gold
nanorods were incubated at room temperature for one hour. These particles were
washed and separated with a magnet and analyzed through SEM imaging to ensure
that electrostatic interactions proved favorable.
Attachment of 4-Mercaptophenol
A 50 mM stock solution of 4-mercaptophenol was prepared in distilled water.
Differing amounts: 2, 5, 10, 32 μL of iron oxide–gold hybrid structures and gold
spheres were added to 4-mercaptophenol allowing the solutions to incubate while
stirring for 30 min before analyzed on Raman spectrometer.
Results and Discussion
The scattering of light as a result of the transmittance of an applied electric field
through the electron cloud occurs via inelastic and elastic collisions. Rayleigh scattering represents the elastic collision of light where the scattered photon has the same
energy as the incident photon. Elastic collisions are the most abundant form of light
scattering from the introduction of incident photons. They represent changes in direction of photons and not changes in vibrational energy [1]. The energy is conserved
in the collision as illustrated in Fig. 3. The dipole changes generated during elastic
collisions, however, has no change in polarizability of the interrogated species.
In the case of inelastic collisions, as known as Raman response, a change in
polarizability is experienced which produces a unique fingerprint scattering signal
that can be matched to a specific analyte of interest. Raman scattering can be used
for analysis of composition and trace analysis of species within complex matrices
using the vibrational information [2]. In contrast to Rayleigh elastic light scattering,
the Raman signal is very weak. Raman scattering is also less likely to occur. When it
does occur, two different type—Stokes and anti-Stokes—forms are produced (Fig. 3).
Stokes scattering occurs when the scattered photon of light is of a lower energy than
the incident light. Anti-Stokes scattering is observed when the incident photon of
light gains energy. The loss or gain of energy is a result of the excitation of the electron
to virtual states or non-quantized short-lived energy states, without the conservation
of energy from the incident photon.
S. E. H. Murph and E. Searles
Iron Oxide–Gold Rods Multifunctional Nanoparticle Synthesis
Gold nanorods were attached to iron oxide through electrostatic interactions. Gold
rods synthesized with cetyltrimethylammonium bromide (CTAB) using the method
previously used in the Murph’s laboratory were used [17]. Iron oxide was treated
with chloroauric acid to ensure the particles preserved a negative surface charge.
The 0.5 mM iron oxide nanospheres, 0.05 M chloroauric acid, and concentrated gold
nanorods were incubated at room temperature for one hour. These particles were
washed and separated with a magnet and analyzed through SEM imaging to ensure
that electrostatic interactions proved favorable.
Attachment of 4-Mercaptophenol
A 50 mM stock solution of 4-mercaptophenol was prepared in distilled water.
Differing amounts: 2, 5, 10, 32 μL of iron oxide–gold hybrid structures and gold
spheres were added to 4-mercaptophenol allowing the solutions to incubate while
stirring for 30 min before analyzed on Raman spectrometer.
Results and Discussion
The scattering of light as a result of the transmittance of an applied electric field
through the electron cloud occurs via inelastic and elastic collisions. Rayleigh scattering represents the elastic collision of light where the scattered photon has the same
energy as the incident photon. Elastic collisions are the most abundant form of light
scattering from the introduction of incident photons. They represent changes in direction of photons and not changes in vibrational energy [1]. The energy is conserved
in the collision as illustrated in Fig. 3. The dipole changes generated during elastic
collisions, however, has no change in polarizability of the interrogated species.
In the case of inelastic collisions, as known as Raman response, a change in
polarizability is experienced which produces a unique fingerprint scattering signal
that can be matched to a specific analyte of interest. Raman scattering can be used
for analysis of composition and trace analysis of species within complex matrices
using the vibrational information [2]. In contrast to Rayleigh elastic light scattering,
the Raman signal is very weak. Raman scattering is also less likely to occur. When it
does occur, two different type—Stokes and anti-Stokes—forms are produced (Fig. 3).
Stokes scattering occurs when the scattered photon of light is of a lower energy than
the incident light. Anti-Stokes scattering is observed when the incident photon of
light gains energy. The loss or gain of energy is a result of the excitation of the electron
to virtual states or non-quantized short-lived energy states, without the conservation
of energy from the incident photon.