Graphene-based contrast agents for photoacoustic and thermoacoustic tomography

Article (PDF Available)inPhotoacoustics 1(3-4):62-67 · December 2013with189 Reads
DOI: 10.1016/j.pacs.2013.10.001
  • 32.6 · Stony Brook University
  • 31.49 · Washington University in St. Louis
  • 32.02 · Center for molecular imaging and nanomedicine, Xiamen University
  • 37.72 · Stony Brook University
Abstract
In this work, graphene nanoribbons and nanoplatelets were investigated as contrast agents for photoacoustic and thermoacoustic tomography (PAT and TAT). We show that oxidized single- and multi-walled graphene oxide nanoribbons (O-SWGNRs, O-MWGNRs) exhibit approximately 5–10 fold signal enhancement for PAT in comparison to blood at the wavelength of 755 nm, and approximately 10–28% signal enhancement for TAT in comparison to deionized (DI) water at 3 GHz. Oxidized graphite microparticles (O-GMPs) and exfoliated graphene oxide nanoplatelets (O-GNPs) show no significant signal enhancement for PAT, and approximately 12–29% signal enhancement for TAT. These results indicate that O-GNRs show promise as multi-modal PAT and TAT contrast agents, and that O-GNPs are suitable contrast agents for TAT.
Short
communication
Graphene-based
contrast
agents
for
photoacoustic
and
thermoacoustic
tomography
§
Gaurav
Lalwani
a,1
,
Xin
Cai
b,1
,
Liming
Nie
b
,
Lihong
V.
Wang
b,2,
*
,
Balaji
Sitharaman
a,3,
**
a
Department
of
Biomedical
Engineering,
Stony
Brook
University,
Stony
Brook,
NY
11794-5281,
USA
b
Optical
Imaging
Laboratory,
Department
of
Biomedical
Engineering,
Washington
University
in
St.
Louis,
Campus
Box
1097,
One
Brookings
Drive,
St.
Louis,
MO
63130,
USA
1.
Introduction
Hybrid
imaging
modalities,
such
as
photoacoustic
(PA)
tomog-
raphy
(PAT)
[1]
and
thermoacoustic
(TA)
tomography
(TAT)
[2],
have
been
developed
for
different
applications.
PAT/TAT
combines
advantages
of
pure
ultrasound
and
pure
optical
imaging/radio
frequency
(rf),
providing
good
spatial
resolution,
great
penetration
depth,
and
high
soft-tissue
contrast.
These
imaging
modalities
are
based
on
detection
of
acoustic
waves
from
an
object
that
absorbs
electromagnetic
(EM)
energy
(laser
in
PAT
and
microwave
in
TAT).
Endogenous
molecules,
such
as
hemoglobin,
melanin,
and
water/
ion,
can
absorb
EM
energy,
producing
acoustic
waves.
High
resolution
PAT
and/or
TAT
enable
functional
brain
imaging
[3],
breast
cancer
detection
[4],
melanoma
detection
[5],
tumor
angiogenesis
[6],
and
functional
molecular
imaging
[2].
However,
in
cases
when
endogenous
molecules
are
insufficient,
exogenous
contrast
agents
(CAs)
are
developed
and
administered.
Contrast-
enhanced
PAT
has
been
applied
in
lymph
node
mapping
[7],
multiscale
imaging
of
tissue
engineering
scaffolds
[8,9],
and
molecular,
cellular,
and
functional
imaging
[10,11].
A
variety
of
CAs
for
PAT
have
been
reported,
such
as,
carbon
nanoparticles
[7,12–
14],
metallic
nanoparticles
[11,15–17],
and
organic
dyes
[18].
In
comparison
to
PAT,
fewer
reports
have
focused
on
development
of
CAs
for
TAT.
Superparamagnetic
iron
oxide
nanoparticles,
single-
and
multi-walled
carbon
nanotubes
(SWCNT
and
MWCNT),
and
air-filled
microbubbles
have
been
investigated
as
CAs
for
TAT
[2,13,19,20].
In
this
work,
we
investigate
efficacy
of
graphene
nanoparticles,
prepared
by
two
widely
used
methods
((1):
longitudinal
unzipping
method
[21],
(2):
modified
Hummer’s
method
of
oxidation
[22])
as
CAs
for
PAT
and
TAT.
We
compare
PA
and
TA
signal
amplitudes
of
oxidized
single-
and
multi-walled
graphene
oxide
nanoribbons
(O-
SWGNRs
and
O-MWGNRs),
and
oxidized
graphene
nanoplatelets
(O-GNPs)
to
pristine
SWCNTs,
pristine
MWCNTs,
pristine
graphite
microparticles
(GMPs),
and
oxidized
graphite
microparticles
(O-
GMP).
2.
Results
and
discussions
O-SWGNRs,
O-MWGNRs,
and
O-GNPs
were
synthesized
as
reported
previously
[22,23].
Pristine
SWCNTs,
MWCNTs,
and
GMPs
Photoacoustics
1
(2013)
62–67
A
R
T
I
C
L
E
I
N
F
O
Article
history:
Received
14
July
2013
Received
in
revised
form
18
September
2013
Accepted
8
October
2013
Keywords:
Graphene
Photoacoustic
tomography
Thermoacoustic
tomography
Contrast
agents
Microwave
imaging
A
B
S
T
R
A
C
T
In
this
work,
graphene
nanoribbons
and
nanoplatelets
were
investigated
as
contrast
agents
for
photoacoustic
and
thermoacoustic
tomography
(PAT
and
TAT).
We
show
that
oxidized
single-
and
multi-
walled
graphene
oxide
nanoribbons
(O-SWGNRs,
O-MWGNRs)
exhibit
approximately
5–10
fold
signal
enhancement
for
PAT
in
comparison
to
blood
at
the
wavelength
of
755
nm,
and
approximately
10–28%
signal
enhancement
for
TAT
in
comparison
to
deionized
(DI)
water
at
3
GHz.
Oxidized
graphite
microparticles
(O-GMPs)
and
exfoliated
graphene
oxide
nanoplatelets
(O-GNPs)
show
no
significant
signal
enhancement
for
PAT,
and
approximately
12–29%
signal
enhancement
for
TAT.
These
results
indicate
that
O-GNRs
show
promise
as
multi-modal
PAT
and
TAT
contrast
agents,
and
that
O-GNPs
are
suitable
contrast
agents
for
TAT.
ß
2013
The
Authors.
Published
by
Elsevier
GmbH.
All
rights
reserved.
§
This
is
an
open-access
article
distributed
under
the
terms
of
the
Creative
Commons
Attribution-NonCommercial-No
Derivative
Works
License,
which
permits
non-commercial
use,
distribution,
and
reproduction
in
any
medium,
provided
the
original
author
and
source
are
credited.
*
Corresponding
author
at:
Department
of
Biomedical
Engineering,
Washington
University
in
St.
Louis,
Campus
Box
1097,
One
Brookings
Drive,
St.
Louis,
MO
63130,
USA.
**
Corresponding
author
at:
Department
of
Biomedical
Engineering,
Bioengineer-
ing
Building
Room
115,
Stony
Brook
University,
Stony
Brook,
NY
11794-5281,
USA.
Tel.:
+1
631
632
1810;
fax:
+1
631
632
8577.
E-mail
addresses:
lhwang@seas.wustl.edu
(L.V.
Wang),
balaji.sitharaman@stonybrook.edu,
balajisitharaman@yahoo.com
(B.
Sitharaman).
1
These
authors
contributed
equally
to
the
work.
2
PAT
and
TAT.
3
Graphene
contrast
agents.
Contents
lists
available
at
ScienceDirect
Photoacoustics
jo
ur
n
al
ho
m
epag
e:
ww
w.els
evier
.c
om
/lo
cat
e/pac
s
2213-5979/$
see
front
matter
ß
2013
The
Authors.
Published
by
Elsevier
GmbH.
All
rights
reserved.
http://dx.doi.org/10.1016/j.pacs.2013.10.001
were
used
as
starting
materials
in
the
preparation
of
O-SWGNRs,
O-MWGNRs,
and
O-GNPs,
respectively.
O-GMPs
are
intermediate
product
formed
during
the
synthesis
of
O-GNPs.
These
nanoma-
terials
were
characterized
by
Raman
spectroscopy
and
electron
microscopy
(EM).
Raman
spectroscopic
characterization
of
SWCNTs,
MWCNTs,
O-SWGNRs,
O-MWGNRs,
GMPs,
O-GMPs,
and
O-GNPs
has
been
reported
previously
[22,24–26].
Table
1
lists
the
size
distribution
of
various
nanomaterials.
Fig.
1
shows
representative
transmission
EM
(TEM)
images
of
all
nanomaterials
used
in
the
study
(scanning
EM
(SEM)
for
GMPs).
SWCNTs
(Fig.
1A)
and
MWCNTs
(Fig.
1B)
were
nanotubes
of
lengths
3–30
m
m
and
0.5–200
m
m,
and
diameters
1–2
nm
and
20–30
nm,
respec-
tively.
O-SWGNRs
(Fig.
1C)
and
O-MWGNRs
(Fig.
1D)
possessed
lengths
0.5–1
m
m
and
0.5–1.5
m
m,
and
diameters
of
3–6
nm
and
60–90
nm,
respectively,
confirming
complete
unzipping
of
SWCNTs
and
MWCNTs
(
p
*diameter).
Pristine
GMPs
were
<45
m
m
in
size
(Fig.
1E).
O-GMPs
(Fig.
1F)
were
loosely
arranged
sheets
of
a
few
layered
graphene
(8
sheets,
size
>1
m
m)
whereas
O-GNPs
(Fig.
1G)
had
2–4
graphene
sheets
and
diameters
of
5–15
nm.
We
have
estimated
that
future
in
vivo
preclinical
safety
(acute
toxicity)
studies
to
establish
the
therapeutic
dosages
of
graphene
would
require
their
administration
at
a
range
of
dosages;
from
50
mg/kg
upto
possibly
500
mg/kg
body
weight
of
the
small
animal
[27].
If
the
graphene
formulations
are
injected
at
a
dose
of
50
or
500
mg/kg
body
weight
of
a
250
g
rat
(total
circulating
blood
volume
12–13
ml),
its
steady
state
blood
concentration
after
the
first
pass
would
be
1
or
10
mg/ml,
respectively.
Thus,
a
median
concentration
of
5
mg/ml
was
chosen
for
this
study.
Since
Fig.
1.
Representative
transmission
electron
microscopy
images
of
(A)
single-walled
carbon
nanotubes
(SWCNTs),
(B)
multi-walled
carbon
nanotubes
(MWCNTs),
(C)
oxidized
single-walled
graphene
nanoribbons
(O-SWGNRs),
(D)
oxidized
multi-walled
graphene
nanoribbons
(O-MWGNRs),
(F)
oxidized
graphite
microparticles
(O-GMP),
and
(G)
exfoliated
graphene
nanoplatelets
(O-GNP).
Image
(E)
is
a
scanning
electron
micrograph
of
pristine
GMPs.
G.
Lalwani
et
al.
/
Photoacoustics
1
(2013)
62–67
63
hemoglobin
is
a
dominant
optical
absorber
producing
strong
PA
signal
in
human
tissue,
efficacy
of
these
nanomaterials
was
compared
with
blood
in
the
NIR
wavelength
window.
Fig.
2A
shows
PA
signal
amplitudes
obtained
from
a
tygon
tube
(I.D.
250
m
m,
O.D.
500
m
m)
filled
with
SWCNT,
MWCNT,
O-SWGNR,
O-
MWGNR,
micro-graphite
flakes,
O-GMP,
O-GNP
and
lysed
bovine
blood
(905–250,
Quad
Five),
respectively.
The
signals
were
normalized
to
that
for
blood
at
740
nm.
At
755
nm
excitation
wavelength,
peak-to-peak
PA
signal
amplitudes
obtained
from
micro-graphite
flakes,
O-GMPs,
and
O-GNPs
were
comparable
to
that
from
blood
alone.
In
contrast,
those
from
SWCNTs,
MWCNTs,
O-SWGNRs
and
O-MWGNRs
were
more
than
5
times
stronger
than
that
from
blood,
in
which,
O-SWGNRs
showed
14
times
stronger
signal.
At
5
mg/ml
concentration,
PA
signal
intensities
obtained
from
gold
nanoparticles
were
3
times
greater,
and
methylene
blue
dye
were
similar,
compared
to
blood
[28,29].
We
detected
a
very
high
signal-to-noise
ratio
(SNR;
ratio
of
the
average
signal
to
the
standard
deviation
of
the
background)
of
O-SWGNRs
at
5
mg/ml.
The
SNR
was
>170
and
suggested
that
the
concentration
of
the
O-
SWGNRs
can
be
as
low
as
0.03
mg/ml
using
PAT.
At
this
low
O-
SWGNR
concentration,
a
2-fold
increase
in
PA
signal
was
measured
compared
to
background
(1.2
mg/ml
DSPE-PEG
in
DI
water)
(Fig.
2B).
These
results
suggest
that
minimum
detectable
concentration
of
O-SWGNRs
will
be
comparable
to
other
PA
contrast
agents
such
as
gold
nanoparticles
[17,30].
Furthermore,
the
results
showed
that
PA
signal
obtained
from
these
nanoma-
terials
exceeded
inherent
blood
signal
over
the
investigated
NIR
bandwidth,
suggesting
their
utility
for
in
vivo
imaging.
Water
and
ions
are
two
well-known
sources
of
microwave
absorbers
in
human
tissue,
and
they
generate
strong
TA
signals.
Therefore,
to
show
that
nanomaterials
can
function
as
CAs
for
TAT,
we
compared
TA
signal
of
nanomaterials
to
that
of
DI
water.
Fig.
3B
shows
TA
signals
obtained
from
a
low-density
polyethylene
(LDPE)
vial
(I.D.
=
6
mm
and
1.5
cc
volume)
filled
with
DI
water,
SWCNTs,
Fig.
2.
(A)
Photoacoustic
spectral
amplitudes
of
blood,
single-walled
carbon
nanotubes
(SWCNTs),
multi-walled
carbon
nanotubes
(MWCNTs),
oxidized
single-walled
graphene
nanoribbons
(O-SWGNRs),
oxidized
multi-walled
graphene
nanoribbons
(O-MWGNRs),
micro-graphite
flakes
(GMPs),
oxidized
graphite
microparticles
(O-GMPs),
and
exfoliated
graphene
nanoplatelets
(O-GNPs).
PA
signal
amplitudes
are
normalized
to
that
of
blood
at
740
nm.
(B)
PA
signal
amplitude
of
O-SWGONRs
at
0.03
mg/ml
concentration
compared
to
background
(1.2
mg/ml
of
DSPE-PEG
solution).
Table
1
Size
distribution
of
various
nanomaterials.
Nanomaterial
Length
Diameter
Single-walled
carbon
nanotubes
(SWCNTs)
3–30
m
m
1–2
nm
Multi-walled
carbon
nanotubes
(MWCNTs)
0.5–200
m
m
20–30
nm
Oxidized
single-walled
graphene
nanoribbons
(O-SWGNRs)
0.5–1
m
m
3–6
nm
Oxidized
multi-walled
graphene
nanoribbons
(O-MWGNRs)
0.5–1.5
m
m
60–90
nm
Pristine
graphite
microparticles
(GMPs)
<45
m
m
Oxidized
graphite
microparticles
(O-GMPs)
>1
m
m
Oxidized
graphene
nanoplatelets
(O-GNP)
5–15
nm
G.
Lalwani
et
al.
/
Photoacoustics
1
(2013)
62–67
64
MWCNTs,
O-SWGNRs,
O-MWGNRs,
GMPs,
O-GMPs,
and
O-GNPs,
respectively.
The
signal
amplitudes
were
normalized
to
DI
water.
Additionally,
TA
signal
amplitude
of
DSPE-PEG
was
comparable
to
DI
water
(Fig.
3C),
and
LDPE
vial
does
not
generate
any
measurable
TA
signal
[13].
At
3
GHz,
the
SNR
of
the
nanomaterials
was
>170,
and
the
nanomaterials
exhibited
10–28%
TA
signal
enhancement
compared
to
DI
water.
To
the
best
of
our
knowledge,
this
is
the
first
study
exploring
and
comparing
efficacy
of
graphene
nanoparticles
prepared
via
longitudinal
‘‘unzipping’’
method
and
Hummer’s
method
as
CAs
for
multimodal
PAT
and
TAT.
These
results
indicate
that
O-GNRs
could
be
used
for
multimodal
PAT
and
TAT
applications,
and
O-
GNPs
are
suitable
CAs
for
TAT.
Bulk
of
the
work
performed
towards
developing
CAs
for
PAT
has
been
focused
on
metallic
nanoparticles,
Fig.
3.
(A)
Schematic
depiction
of
the
experimental
setup
for
thermoacoustic
signal
measurements.
(B)
Thermoacoustic
signal
amplitudes
of
water,
single-walled
carbon
nanotubes
(SWCNTs),
multi-walled
carbon
nanotubes
(MWCNTs),
oxidized
single-walled
graphene
nanoribbons
(O-SWGNRs),
oxidized
multi-walled
graphene
nanoribbons
(O-MWGNRs),
micro-graphite
flakes
(GMPs),
oxidized
graphite
microparticles
(O-GMP),
and
exfoliated
graphene
nanoplatelets
(O-GNP)
at
3
GHz.
TA
signals
are
normalized
to
that
of
water
at
3
GHz.
(C)
TA
signal
amplitude
of
DSPE-PEG
compared
to
DI
water.
G.
Lalwani
et
al.
/
Photoacoustics
1
(2013)
62–67
65
organic
dye
molecules,
and
carbon
nanotubes.
In
comparison
to
those
CAs,
graphene
possesses
several
benefits:
(1)
Compared
to
carbon
nanotubes,
graphene
possesses
larger
surface
area,
lower
aspect
ratio,
and
better
dispersibility
in
most
biological
media.
These
properties
are
important,
for
most
in
vivo
applications.
Furthermore,
colloidal
dispersions
(with
high
stability
and
less
aggregation)
of
graphene
sheets
can
be
achieved
without
impurities
that
may
be
harmful
in
biological
systems
[31,32].
(2)
The
sp
2
bonded
carbon
sheets
of
graphene
can
be
directly
functionalized
for
targeting
and
drug
delivery
[33].
For
other
PAT/
TAT
CAs,
such
as
gold
nanoparticles
and
organic
dye
molecules,
to
disperse
and
stabilize
gold
nanoparticles
in
solution
or
embed
organic
dye
molecules,
functionalization
is
performed
on
the
biocompatible
coating/capping
agent.
(3)
O-GNPs
and
O-GNRs
have
been
reported
as
CAs
for
other
whole-body
imaging
applications
such
as
magnetic
resonance
imaging
[22]
and
nuclear
imaging
[34].
Therefore,
they
can
be
developed
as
multimodal
CAs
that
provide
complementary
information
at
micro-
to
macro-
scopic
length
scales.
(4)
Graphene
can
be
developed
as
ther-
agnostic
(simultaneous
therapy
and
diagnostics)
agent
combining
PAT/TAT
molecular
imaging
and
NIR-induced
hyperthermia
[33].
Due
to
these
unique
features,
graphene
may
serve
as
a
platform
for
the
design
of
multi-modal
imaging
and
multi-therapeutic
approaches.
Indeed,
several
in
vitro
and
in
vivo
safety
and
efficacy
studies
on
these
graphene
nanoparticles
have
been
reported
for
various
biomedical
applications
[23,35].
3.
Materials
and
methods
3.1.
Synthesis
and
characterization
of
nanomaterials
SWCNTs
(Cheap
Tubes
Inc.,
VT,
USA)
and
MWCNTs
(Sigma
Aldrich,
NY,
USA)
were
used
as
received.
O-SWGNRs,
O-MWGNRs,
O-GMPs,
and
O-GNPs
were
synthesized
and
characterized
as
reported
previously
[22–24].
All
nanomaterials
were
dispersed
at
5
mg/ml
in
DSPE-PEG
for
PA
and
TA
measurements.
3.2.
Photoacoustic
(PA)
imaging
A
deep
reflection-mode
PA
imaging
system
was
used
(Scheme
1
in
Ref.
[36])
for
PA
tests
of
graphene
samples.
A
tunable
Ti:sapphire
laser
(LT-2211A;
Lotis
TII,
Minsk,
Belarus)
pumped
by
a
Q-switched
Nd:YAG
(LS-2137;
Lotis
TII)
laser
was
used
for
PA
excitation
(pulse
width:
5
ns,
pulse
repetition
rate:
10
Hz).
A
5-MHz
central
frequency,
spherically
focused
ultrasonic
transducer
(V308;
Panametrics-NDT,
Waltham,
MA,
USA),
low-noise
amplifier
(5072PR;
Panametrics-NDT),
a
digital
oscilloscope
(TDS
5054;
Tektronix,
Beaverton,
OR,
USA)
were
used
to
acquire,
amplify,
and
record
signals.
The
reported
PA
signal
amplitudes
have
been
normalized
for
laser
fluence
at
their
corresponding
wavelengths.
3.3.
Thermoacoustic
(TA)
imaging
Fig.
3A
is
a
schematic
depiction
of
the
experimental
setup
for
TA
measurements.
TA
results
were
obtained
from
a
TAT
system
with
a
3.0-GHz
microwave
generator
(pulse
width
=
0.6
m
s,
repetition
rate
=
10
Hz)
and
a
20
dB
amplifier.
The
pulses
(average
power
density
=
4.5
mW/cm
2
,
within
safety
standard)
were
guided
toward
the
target
through
a
horn
antenna
(11
cm
7
cm)
[37].
A
1-MHz
spherically
focused
transducer
with
a
bandwidth
of
70%
(V314,
Panametrics,
Olympus)
was
used
to
receive
TA
signals
from
samples
placed
in
a
plastic
tank
filled
with
mineral
oil
for
ultrasound
coupling.
The
received
TA
signals
were
amplified
and
stored
by
a
data-acquisition
(DAQ)
card
(CS
14200;
Gage
Applied,
IL)
[38].
The
microwave
generator
simultaneously
triggered
data
acquisition.
Conflict
of
interest
statement
The
authors
declare
no
conflict
of
interest.
Acknowledgments
We
are
grateful
to
Sandra
Matteucci
for
proof
reading
of
the
manuscript.
Our
work
was
sponsored
by
NIH
Director’s
New
Innovator
Award
1DP2OD007394-01
(to
S.B.),
Wallace
H.
Coulter
Foundation
(S.B.),
and
NIH
grants
R01
EB008085,
R01
CA140220,
R01
CA157277,
R01
CA159959,
U54
CA136398,
and
DP1
EB016986
NIH
Director’s
Pioneer
Award
(to
L.V.W.).
L.V.W.
has
a
financial
interest
in
Microphotoacoustics,
Inc.
and
Endra,
Inc.,
which,
however,
did
not
support
this
work.
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Chowdhury
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Lalwani
G,
Zhang
K,
Yang
JY,
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AM,
Farshid
B,
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B,
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Gaurav
Lalwani
received
his
B.Tech.
in
Biotechnology
from
SRM
University,
Chennai,
India,
in
2010,
and
M.S.
in
Biomedical
Engineering
from
Stony
Brook
University,
New
York,
in
2012.
He
is
currently
working
towards
a
Ph.D.
in
Biomedical
Engineering
at
Stony
Brook
University
under
the
guidance
of
Dr.
Balaji
Sitharaman.
His
research
areas
include
biomaterials
and
regenerative
medicine.
He
is
working
on
the
design
of
nanoparticle-reinforced
biodegradable
polymeric
nanocomposites
and
multi-
functional
three-dimensional
macroscopic
all-carbon
scaffolds
for
tissue
engineering
applications,
and
graphene-based
nanostructures
as
multimodal
contrast
agents
for
medical
diagnostics.
Xin
Cai
earned
his
M.S.
degree
at
Huazhong
University
of
Science
and
Technology,
Wuhan,
China,
in
2008.
He
is
currently
a
research
associate
in
the
Optical
Imaging
Laboratory,
Department
of
Biomedical
Engineering,
Washington
University
in
St.
Louis.
His
research
inter-
ests
are
the
developments
of
non-ionizing
and
non-
invasive
novel
biomedical
imaging
techniques,
includ-
ing
photoacoustic
imaging,
fluorescence
imaging,
and
ultrasonic
imaging.
He
has
published
22
papers
in
peer-
reviewed
journals.
Dr.
Liming
Nie
earned
his
B.S.
in
2005
and
Ph.D.
in
2010,
both
in
Optics,
from
South
China
Normal
University.
His
Ph.D
project
was
focused
on
microwave-induced
ther-
moacoustic
tomography
and
its
biomedical
application.
In
August
2010,
he
joined
Optical
Imaging
Lab
at
Washington
University
in
St.
Louis
under
the
mentor-
ship
of
Dr.
Lihong
V.
Wang.
His
project
involved
nonin-
vasive
photoacoustic
imaging
of
the
primate
brain
and
reconstruction
correction
for
imaging
distortion.
In
Oc-
tober
2012,
he
joined
Dr.
Shawn
Chen’s
Laboratory
of
Molecular
and
Nanomedicine
(LOMIN),
NIBIB,
NIH.
His
current
research
is
focused
on
developing
photoacous-
tic/ultrasound
imaging
system,
image
processing,
and
molecular
therapeutics.
Lihong
V.
Wang
earned
his
Ph.D.
degree
at
Rice
University,
Houston,
Texas
under
the
tutelage
of
Robert
Curl,
Richard
Smalley,
and
Frank
Tittel.
He
is
Gene
Beare
Distinguished
Professor
at
Washington
Univ.
His
laboratory
invented
functional
photoacoustic
tomography,
3D
photoacoustic
microscopy,
and
time-reversed
ultrasonically
encoded
(TRUE)
optical
focusing.
He
has
published
342
journal
articles
and
delivered
357
invited
talks.
His
Google
Schol-
ar
h-index
and
citations
have
reached
80
and
25,500,
respectively.
He
has
received
34
grants
as
PI
with
a
budget
of
$41M.
He
is
the
Editor-in-Chief
of
the
Journal
of
Bio-
medical
Optics.
He
co-founded
two
companies
to
com-
mercialize
photoacoustic
tomography.
He
is
a
Fellow
of
the
AIMBE,
OSA,
IEEE,
and
SPIE.
His
book
entitled
‘‘Biomedical
Optics:
Principles
and
Imaging’’
won
the
Goodman
Award.
He
was
awarded
OSA’s
C.E.K.
Mees
Medal
and
IEEE’s
Technical
Achievement
Award
for
‘‘seminal
contributions
to
photoacoustic
tomography
and
Monte
Carlo
modeling
of
photon
transport
in
biological
tissues
and
for
leadership
in
the
international
biophotonics
community’’.
Balaji
Sitharaman
is
an
Assistant
Professor
of
Biomedical
Engineering
at
Stony
Brook
University.
He
received
his
B.S.
(2000)
from
the
Indian
Institute
of
Technology
at
Kharagpur.
He
received
his
M.A
and
Ph.D.
(2005)
from
Rice
University,
where
he
also
completed
his
postdoc-
toral
research
(2005–2007)
as
the
J.
Evan
Attwell-Welch
Postdoctoral
Fellow
at
the
Richard
E.
Smalley
Institute
for
Nanoscale
Science
and
Technology.
Sitharaman’s
research
program
is
at
the
interface
of
nanotechnology,
regenerative
and
molecular
medicine
and
synergizes
the
advancements
in
each
of
these
fields
to
tackle
problems
related
to
diagnosis/treatment
of
disease
and
tissue
regeneration.
He
is
the
author
of
over
40
peer-reviewed
publications.
He
has
received
several
awards
for
his
research
including
NIH
Director’s
New
Innovator
Award
from
the
National
Institute
of
Health,
the
Idea
Award
from
the
Department
of
Defense,
the
Carol
M.
Baldwin
Breast
Cancer
Research
Award
from
the
Carol
Baldwin
Foundation
and
the
George
Kozmetsky
Award
from
the
Nanotechnology
Foundation
of
Texas.
G.
Lalwani
et
al.
/
Photoacoustics
1
(2013)
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67
    • "Graphene can be covalently or non-covalently functionalized with several chemical moieties (for instance amine) or biological molecules (such as nucleic acids and proteins). Oxidized graphene nanoparticlebased formulations has been extensively explored for several biomedical applications such as bioimaging [33][34][35], drug and gene delivery [36][37][38], photothermal therapy [39,40], tissue engineering [41][42][43], and stem cell technology [44,45]. Pristine or nearly pristine (oxidized graphene treated with reducing agents) graphene have also been investigated for several biomedical applications [27,35,46,47]. "
    [Show abstract] [Hide abstract] ABSTRACT: Graphene based nanomaterials possess remarkable physiochemical properties suitable for diverse applications in electronics, telecommunications, energy and healthcare. The human and environmental exposure to graphene-based nanomaterials is increasing due to advancements in the synthesis, characterization and large-scale production of graphene and the subsequent development of graphene based biomedical and consumer products. A large number of in vitro and in vivo toxicological studies have evaluated the interactions of graphene-based nanomaterials with various living systems such as microbes, mammalian cells, and animal models. A significant number of studies have examined the short- and long-term in vivo toxicity and biodistribution of graphene synthesized by variety of methods and starting materials. A key focus of these examinations is to properly associate the biological responses with chemical and morphological properties of graphene. Several studies also report the environmental and genotoxicity response of pristine and functionalized graphene. This review summarizes these in vitro and in vivo studies and critically examines the methodologies used to perform these evaluations. Our overarching goal is to provide a comprehensive overview of the complex interplay of biological responses of graphene as a function of their physio-chemical properties.
    Full-text · Article · May 2016
    • "More thorough investigations are currently underway to better understand the differences in cellular uptake of various graphene nanoparticles, including their uptake mechanism and the reasons for the observed variation in cell death. Graphene-based formulations show promise as cellular contrast agents for bioimaging and as vectors for drug/gene delivery appli- cations [6,8,58,59]. These advancements offer opportunities to introduce these nanomaterials for stem cell imaging and therapy. "
    [Show abstract] [Hide abstract] ABSTRACT: We report the effects of two-dimensional graphene nanostructures; graphene nano-onions (GNOs), graphene oxide nanoribbons (GONRs), and graphene oxide nanoplatelets (GONPs) on viability, and differentiation of human mesenchymal stem cells (MSCs). Cytotoxicity of GNOs, GONRs, and GONPs dispersed in distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)] (DSPE-PEG), on adipose derived mesenchymal stem cells (adMSCs), and bone marrow-derived mesenchymal stem cells (bmMSCs) was assessed by AlamarBlue and Calcein AM viability assays at concentrations ranging from 5 to 300 μg/ml for 24 or 72 h. Cytotoxicity of the 2D graphene nanostructures was found to be dose dependent, not time dependent, with concentrations less than 50 μg/ml showing no significant differences compared to untreated controls. Differentiation potential of adMSCs to adipocytes and osteoblasts, - characterized by Oil Red O staining and elution, alkaline phosphatase activity, calcium matrix deposition and Alizarin Red S staining - did not change significantly when treated with the three graphene nanoparticles at a low (10 μg/ml) and high (50 μg/ml) concentration for 24 h. Transmission electron microscopy (TEM) and confocal Raman spectroscopy indicated cellular uptake of only GNOs and GONPs. The results lay the foundation for the use of these nanoparticles at potentially safe doses as ex vivo labels for MSC-based imaging and therapy.
    Full-text · Article · Jun 2014
    • "GNPs could also be intercalated or covalently functionalized with important elements (e.g. manganese, iodine) in medicine to develop highly efficacious contrast agents for magnetic resonance imaging (MRI) [8,9], computed tomography (CT) [10] , and their intrinsic electromagnetic properties could be harnessed towards the development of probes for fluorescence [4], photoacoustic and thermoacoustic imaging [11]. There is now a wide body of research documenting the toxicology and pharmacology of fullerenes, metallofullerenes and carbon nanotubes (CNTs) [1e3,12]. "
    [Show abstract] [Hide abstract] ABSTRACT: Graphene nanoparticle dispersions show immense potential as multifunctional agents for in vivo biomedical applications. Herein, we follow regulatory guidelines for pharmaceuticals that recommend safety pharmacology assessment at least 10 – 100 times higher than the projected therapeutic dose, and present comprehensive single dose response, expanded acute toxicology, toxicokinetics, and respiratory/cardiovascular safety pharmacology results for intravenously administered dextran-coated graphene oxide nanoplatelet (GNP-Dex) formulations to rats at doses between 1 and 500 mg/kg. Our results indicate that the maximum tolerable dose (MTD) of GNP-Dex is between 50 mg/kg ≤ MTD < 125 mg/kg, blood half-life < 30 min, and majority of nanoparticles excreted within 24 h through feces. Histopathology changes were noted at ≥250 mg/kg in the heart, liver, lung, spleen, and kidney; we found no changes in the brain and no GNP-Dex related effects in the cardiovascular parameters or hematological factors (blood, lipid, and metabolic panels) at doses < 125 mg/kg. The results open avenues for pivotal preclinical single and repeat dose safety studies following good laboratory practices (GLP) as required by regulatory agencies for investigational new drug (IND) application.
    Full-text · Article · May 2014
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