Page 153 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

6.5 Cross-section absorption of graphene oxide 151

FIGURE 6.7
(A) Temporal profile of temperature versus time of GO and (B) filtering of Plat a.

temperature ϕ ϕ= 0 e i2 π ft and T = Te i2 π ft in the equation above, the magnitude of T = T 0 0 e i 2 π f t
= ei2πft
0
absorption coefficient is:
2 πρ
fCT
µ = 0 (6.22)
a
ϕ o µa =2πfρCT o
0
So, the absorption cross-section of the graphene oxide is calculated using the
following equation:
*
µ = σ C (6.23) µa=σ*C
a
where σ is absorption cross-section (mL/mg m), and C is the corresponding concen- σ
tration (mg/mL).
Temperature per pulse, T , is calculated by placing 400 µL of the graphene oxide in 96
0
well-plate, irradiating with a 808 nm NIR laser pulse (2 Hz at 50% duty cycle) and moni-
toring temperature rise for a minute. Then the measured temporal profile is filtered with
a bandpass filter centered at 2 Hz, to make sure that the slope is not affected by intensity
noise (Fig. 6.7). The steady-state temperature per pulse for GO was 0.16 ± 0.01 °C. By
2 3
3
2
f
substituting ϕ = 1.77(W/cm), ρ = 1001.77(kg/m), C = 4178.62 (J/kgK), and = 2Hz, f  =1.77 (W/cm )(kg/m )
ρ C=4178.62 (J/kg K)=2 Hz

=1001.77
0
0
−1
the absorption cross-section of GO was 19 ± 1.2 (mL(mg cm) ).
Laser-assisted cancer therapy is a highly efficient and minimally invasive method
with the ability to absorb incident light and convert it to heat or singlet oxygen to
destroy cancer cells. Several organic and inorganic materials have been investigated
for laser-assisted cancer therapy. PDT and PTT have been successfully applied for
cancer therapy due to several advantages including inducing cancer cells to apoptosis
as well as sensitize cancer cells to chemotherapy, immunotherapy and gene therapy.
An ideal photothermal or photodynamic transducers must meet several requirements
including having a tunable light-matter response, having high cross-section absorp-
tion, having deep penetration depth, needing a simple modification process and
having an efficient tumor accumulation. Furthermore, to improve therapeutic out-
comes, a combination of other imaging and treatment approaches have been inves-
tigated. Also, administrating photosensitive agent in drug delivery vehicles provide
the opportunity for fabricating stimuli-sensitive drug delivery systems which have
the ability to increase localize delivery. A multifunctional system integrating into a
single platform has a potential application in a large verity of diseases. Several math-
ematical and experimental studies focused on investigating the optical properties of
nanoparticles.