BIOMAGNETISM: BIOMEDICAL APPLICATIONS OF

BIOMAGNETISM: BIOMEDICAL
APPLICATIONS OF NANOMAGNETISM
1.
2.
3.
4.
5.
6.
MRI contrast agents
Magnetic separation
Drug delivery
Sensors
Hyperthermia
Emerging areas
N
Sara A. Majetich
Physics Dept.
Carnegie Mellon Univ.
Pittsburgh, PA 15213 USA
[email protected]
S
Bio-nanomagnetism
• Magnetic fields disturb normal biological function
much less than electric fields.
• Use the power of nanomagnetism as a tool, with
some constraints to probe complex biological
systems
N
S
Bio-nanomagnetism Physics
particle magnetic moment,  = MsV
2. Generate Magnetic Field –
MR sensing, MRI contrast agents
S
N
Ab
mAb
Magnetoresistive
Sensor
O H
H O
MRI contrast agent
3. Dissipate Energy – Hyperthermia
Power dissipation
Electromagnetic
Wave
Heat
H
H
H
O
H
H O
Magnetic Force F = B
H
1. Exert Force – Separation,
Drug delivery
MRI CONTRAST AGENTS
2. Particle moment generates a
Magnetic Field
• Fringe field of the magnetic particle
causes faster relaxation of nuclear
moments of hydrogen atoms (1H) in
water molecules nearby
• Remove water background for
higher contrast
Magnetic resonance
imaging (MRI)
Spin Echo in Magnetic
Resonance
m precesses about a static field B0
Apply rf field pulse to rotate by /2
Local field variations cause dephasing
Apply rf field pulse to rotate by 
m precesses back to lie parallel to B0
Wikipedia!
Magnetic Resonance Longitudinal
and Transverse Relaxation
m precesses about a static field B0
Apply rf field pulse to rotate by /2
Local field variations cause dephasing
Apply rf field pulse to rotate by 
m precesses back to lie parallel to B0
mxy – transverse
mz - longitudinal
Q. A. Pankhurst, et al., J. Phys. D 36, R167 (2003)
Magnetic Resonance
Bloch-Bloembergen equations
mz
ms  mz
 
  m  B 
z

t
T1

mx,y
ms  mx,y
 
  m  B 
x,y

t
T2

2 characteristic times, T1 and T2
Contrast agents change local value of B --- Form images based
on T1 or T2 relaxation times
Contrast Agents
Standard: molecular Gd3+(DTPA) – Affects
T1 , regions with contrast look brighter
mz
ms  mz
 
  m  B 
z
T1
t
mx,y
ms  mx,y
 
  m  B 
x,y

t
T2

Now FDA-Approved: Iron oxide
nanoparticles (FeridexR, EndoremR) – Much
bigger moment, affects T2 , regions with
contrast look darker
Multicolor MRI?
Get homogeneous field between pair of coupled magnetic discs,
with magnitude determined by disc size, thickness, and spacing
G. Zabow, et al. Nature 453 1058 (2008)
Multicolor MRI
Measured MRI signal
from R, G, and B
patterned with different
types of discs, each with
a different resonance
frequency
Diameters 2-10 microns
Electroplated Ni
Not at in vivo stage yet
G. Zabow, et al. Nature 453 1058 (2008)
MAGNETIC SEPARATION
1. Exert Force – Separation, Drug delivery
Magnetic Force F = B
S
N
Ab
mAb
Q. A. Pankhurst, et al. J. Phys. D: Appl. Phys. 36 R167-R181 (2003).
Quadrupole Magnetic Separation
F. Carpino, et al. J. Magn. Magn. Mater. 311 383 (2007).
Q. A. Pankhurst, et al. J. Phys. D: Appl. Phys. 36 R167-R181 (2003).
High Field Gradient Magnetic
Separation
Co90Ta5Zr5 film on patterned
Si3N4 membrane
C. M. Earhardt, et al., J. Magn. Magn.
Mater. 321, 1436-1439 (2009).
MAGNETIC DRUG DELIVERY
1. Exert Force – Separation,
Drug delivery
Magnetic Force F = B
S
N
Ab
mAb
Systemic Therapy
Drug Targeting
Urs Hafeli
Towards Drug Targeting with
Intravascular Magnetic Microspheres
Urs Hafeli
University of British Columbia
Representative image
Vancouver, CANADA
[email protected]
www.magneticmicrosphere.com/hafel
i_lab/
Magnetic Drug Targeting
Drug delivery to tumours, tissues, organs, wounds
– Requires both guidance and holding
• Therapeutic applications
– Chemotherapy
– Radioembolization
– Dissolving of blood clots
– Gene therapy
– Magnetic hyperthermia
• Diagnostic applications
– MRI contrast enhancement
– Stem cell delivery and survival analysis
Urs Hafeli
Physiological Basis of Magnetic
Targeting
Urs Hafeli
Solid Tumor Drug Targeting
Drugs can accumulate in
solid tumors even without
magnetism because of
leaky vasculature, which
leaves gaps between
endothelial cells
Z. Hu, Y. Sun, and A. Garen, Proc. Nat. Acad. Sci. 96 8161-8166 (1999).
Size of Drug Targeting Particles
• Intravascular behaviour
embolization 
• Magnetic forces
Fm  Fd
4 3 dB0
 R H
 6Rv
3
dx
magnetic control 
 1 µm in size as a
compromise
Urs Hafeli
Normal Batch of Biodegradable
Microspheres
Urs Hafeli
Radiolabelling
O
O
O
O
HO
+
nN
N
N
SnR2
O
O
HO
C
O
n
N
N
m
N
O
[M(CO)3]+
HO
O
Bind radioactive
technicium isotope to magnetic
O
nanoparticles,
use magnetic
fields for guidance, measure
C
N
O
N
radiation from TcN M(CO) +
O
n
m
3
Urs Hafeli
Lung Perfusion Imaging
SPECT/CT
Urs Hafeli, Univ. of British Columbia
Cellular Interactions
Combined magnetic drug targeting, hyperthermia and drug release
Drug release
Swollen PNIPAM Shell.
Slow drug release
Dox loaded
PNIPAM shell
Magnetic drug targeting
T < LCST
Hyperthermia
MNP
core
Tumor
T > LCST
Pre-injection MRI
PNIPAM Shell collapse.
Fast drug release
Dox – PNIPAM – Iron Oxide Thermoresponsive Composite Magnetic Nanoparticles
Hyperthermia + drug release
Controlled drug release
Post-injection MRI
Targeted Dox loaded MNP
Dox release: 36% in 1 h
S. Purushotham & R.V. Ramanujan, Acta Biomat, in press.
S. Purushotham, P.E.J. Chang, H. Rumpel, I.H.C. Kee,
R.T.H. Ng, P.K.H. Chow, C.K. Tan and R.V. Ramanujan,
Nanotechnology, 20, 305101 (2009)
R.V. Ramanujan Nanyang Technological Univ., Singapore.
Histology
MAGNETIC SENSORS
2. Particle Generates a Magnetic Field
Field can change the
direction of the free layer
in the magnetoresistive
sensor if particle close by
Many types of
sensors – 2D and 3D
Specific
Linker
S
Magnetic
Nanoparticle
Giant Magnetoresistance
Spin Up e-
Low R channel
High R channel
Spin Down eFM
NM FM
Spin Up e-
Overall Low R
for Parallel M
Medium R
Medium R
Spin Down eFM
FM
Higher overall R
for Antiparallel M
Magnetoresistive Sensors
R for device different in parallel, antiparallel orientations of
magnetic layers
Free layer
or
R
Fixed layer
Si substrate
The fringe field of magnetic particles can change the
magnetization in the free layer
Magneto-Nano Blood Scanner for Cancer
Using similar principles employed in the magnetic storage industry, Prof. Shan Wang’s group at Stanford has
developed a magneto-nano “blood scanner” for detecting cancer. By using magnetic nanoparticles to ‘tag’
proteins indicative of cancer and reading them out using magnetic sensors Wang’s group has demonstrated
much higher sensitivity (1 picogram/mL or femto-molar level) than conventional optical fluorescence assays,
Lead
Se
ns
or
enabling earlier cancer detection.
Lead
Osterfeld, Yu, et al., PNAS, Dec. 30, 2008
Gaster, Hall et al., Nature Medicine, in press
Magneto-Nano Blood Scanner for Cancer
With magneto-nano sensor chips, 7 candidate cancer markers, spiked at 1 pico-gram per milliliter and ranging
from 5 to 100 femto-molar concentrations, have been detected simultaneously on a single chip in about one
hour! This result indicates that the technology is suitable for cancer early detection, cancer chemotherapy
monitoring, and even drug development.
Osterfeld, Yu, et al., PNAS, Dec. 30, 2008
GMR Immunoassay
Use both direct and
indirect sandwich
enzyme-linked
immunosorbent assays
(ELISA)
Mark Tondra, Diagnostic Biosensors
K. Taton, et al. J. Magn. Magn. Mater. 321 1679-1682 (2009)
GMR-Based Lab On a Chip
For rapid diagnosis of sepsis
J. Schotter, et al., J. Magn. Magn. Mater. 321, 1671-1675 (2009).
Relaxometry
3D sensor – doesn’t require particles to be within 50 -100 nm
N. L. Adolphi, et al., J. Magn. Magn. Mater. 321 1459-1464 (2009).
D. Eberbeck, et al., J. Magn. Magn. Mater. 321 1628-1631 (2009).
Source Localization by SQUID Relaxometry
SQUID Image
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MRI: Three slices from a T2-weighted MRI of a
mouse with two human breast tumors. Tumors were
injected with anti-Her-2/neu labeled nanoparticles
(Ocean Nanotech SHP-30), indicated by arrows.
SQUID relaxometry: Least-squares fit of field map obtained from same
mouse (above) identifies two magnetic sources: m1 (left) = 1.40 x 10-7 J/T, m2
(right) = 0.77 x 10-7 J/T, separated by 1.5 cm, in agreement with MRI.
Natalie L. Adolphi, Kimberly Butler, Debbie M. Lovato, Richard S. Larson (University of New
Mexico) Trace E. Tessier, Howard C. Bryant, Edward R. Flynn (Senior Scientific, LLC)
Magnetic Susceptibility
AC driving field H(t) drives magnetization M(t)
- Magnetic susceptibility
  M/H (low field)
- in-phase component of susceptibility
'
- out-of-phase component "(energy loss)
IRM Quarterly, Univ. of Minnesota
Brownian Relaxation Sensor
3
 d hydro



B  
 2k B T 


3D
S.-H. Chung, et al., J. Appl. Phys. 97,
10R101 (2005).
Binding events change
rotation frequency
newfig1
  
  B

Controlled
Rotation
H
Torque in
external
field
No Hc due to physical rotation in
water, but dried powder has Hc
Could control surface exposed to
different bio-functionalities
X. Xu, G. Friedman, K. D. Humfeld, S. A. Majetich, and S. A. Asher, Adv. Mater. 13,
1681 (2001).
X. L. Xu, S. A. Majetich, and S. A. Asher, J. Am. Chem. Soc. 124, 13864-13868 (2002).
Magnetically Guided Plasmonic Sensors
Gold
Shell
Adsorbed
Biomolecule
Magnetic
core
Magnetic force
• Goal: Guide individual, internalized Fe
oxide/Au nanoparticles to map the local
chemistry in different regions of cell
Specific binding of target molecules to
functionalized nanoparticles causes a
local dielectric change and gives rise
to plasmonic responses
Challenges:
• Dual functionality in single particles
• Plasmonic imaging of single particles in
cell environment
• Overcoming viscous drag forces
Target
protein
Magnetic
Force
Surface Plasmon Resonance
h
Electric field
Peak shift under
different solvent
environments*
• Collective excitation of electrons within the conduction band, leading to
an in-phase oscillation.
• Au, Ag have strong plasmon scattering peaks in the visible range
• Plasmon energy sensitive to changes in the local dielectric environment .
*McFarland and Van Duyne, Nano Letter, 3 (2003) 1057
S. Link and M.A. El-Sayed, Int. Review in Physical Chemistry, Vol. 19 2000, 409
Plasmonic
Sensing
What can plasmonic
responses be used
for?
1Plasmonic
responses from gold nanoparticles are
used to detect the present of DNA. This observation
pointed toward the use of nanoparticles in assays
for the detection of oligonucleotides.
How are we going to
detect the signal from
single nanoparticle?
3Plasmonic
responses
from silver nanoparticles
under optical darkfield
microscopy
2Plasmonic
responses from gold nanoparticles
have been used as a colorimetric sensor to study
the protein cytochrome C conformation changes
• Resonant Rayleigh scattering efficiencies equivalent to ~ 106 fluorophores
have been reported with zeptomole sensitivity!
1
2
C.S. Thaxton, et al., MRS Bulletin, Vol. 30, 2005, 376
SW. Chah, et al., Chemistry & Biology, 2005, Vol. 12, 323
3
McFarland and Van Duyne, Nano Letter, 3 (2003) 1057
Au-coated 35 nm Iron Oxide Cores
N
S
Mu-metal tip and
solenoid
J.-K. Lim, C. Lanni, F. Lanni, R. D. Tilton, S. A. Majetich (unpublished).
Sonic Wave Emission by Magnetic Particles
microphones
micropho
ne
r
Sonic wave ∝1/r
Magnetic field ∝1/r3
Deep mapping of SLNs
Magnetic
nanoparticles
Imaging
Established techniques
of ultrasonic imaging
M. Abe, et al. Tokyo Institute of Technology
MAGNETIC HYPERTHERMIA
3. Dissipate Energy – Hyperthermia
Electromagnetic
Wave
Heat
Power dissipation
Hyperthermia – > 43 °C – cells more sensitive to
chemotherapy drugs and radiation
Ablation - > 50 °C – kill cells directly by heating
Many types of hyperthermia: Direct, electrical, ultrasound,
photothermal, magnetic (where is magnetic hyperthermia
superior?)
Magnetic Hyperthermia
Magnetic dissipation
U    0
HAC
T
t

MdH
P = fU = 0”fH2
Power loss ~ T
FDA requirements:
Hmaxf < 4.85 x 108 A-turns/m-s
- with typical fields, fmax < 1.2 MHz
- Otherwise stimulate nerves and cause pain
W. J. Atkinson, et al., IEEE Trans. Biomed. Eng. 31 70-75 (1984).
Magnetic
Hyperthermia
Frequency Dependent
Power Losses
For Bulk Ferromagnetic Materials
in AC Magnetic Fields
Power Loss per Cycle:
Ploss = Physteretic + Peddy current + Panomalous
= Whysf + kB2d2f2 + Panom(f)

P
f
Anomalous
Eddy Current
Whys
Hysteretic
Frequency, f
B
Whys
H
 = resistivity
Are Superparamagnets Best?
• Many papers claim that superparamagnetic particles are best for
hyperthermia, but these particles have no magnetic energy losses
• Particles areSP in nearly DC measurements, but loops open up
at AC frequencies used for hyperthermia
• Particles that look SP DC probably have hysteresis AC
800 Hz
10
FeCo composite hysteresis loops
at different frequencies
5
(
)
100 Hz
0
5000 Hz
A. K. Giri, K. M. Chowdary, and S. A.
Majetich, Mater. Physics and Mechanics
1, 1-10 (2000).
-5
-10
-120
-80
-40
0
H (Oe)
40
80
120
Hyperthermia Figures of Merit
SAR – Specific absorption ratio – Energy absorbed per g
Fe
Thermal dose – Ought to be the energy transferred (kT) over
the time of the dose t, but not yet standardized
Big Question: What happens at elevated T that leads to
cell sensitivity and death?
- heat shock proteins?
Magnetic Hyperthermia
Water
Bath
Apparatus to
measure
thermal dose in
rat livers
Unmixed Heat
Exchanger
Controlled
Rate Pump
Controlled
Rate Pump
Perfusion
Chamber
Oxygenator
Programable
Controller
Temperature
Sensor
Power Switch
Magnetic
Coil
Perfused
Rat Liver
AC Generator
Yoed
Yoed Rabin, Carnegie Mellon
Univ.Rabin,
Carnegie Mellon Univ.,
Mechanical Engineering Dept.
Magnetic Hyperthermia and the
Bioheat Equation
Fe3O4 Particle
T1
1c1
 k1 2T1  P
t
Surrounding tissue
T2
 2c 2
 k 2 2T2
t
JitKang Lim and S. A. Majetich (unpublished)
A single magnetic nanoparticle generates enough heat to raise the local T
by ~ 10-8 K, so NO SINGLE PARTICLE HYPERTHERMIA
Y. Rabin, Int. J. Hyperth. 18 194-202 (2002).
TEM Particle
Sizes
TEM of synthesized particles
yields:dAS = 10.65 ± 1.70nm
Primary particle size is similar,
but clustering is hard to measure.
Similar analysis of the Fluidmag
DX gives:dFM = 9.5 ± 4.0 nm
AC Magnetisation Experiments
•AC hysteresis measurements were
taken in a solenoid permeameter,
Hmax was kept fixed and M was
measured over a frequency range of
1-50 kHz
•There is no hysteresis at low f, but
it develops at higher f.
•The dispersed sample showed no
hysteresis at these frequencies.
AC Magnetisation Theory
•Given the particle diameter is >5 nm, we expect no Néel rotation of
the moments here, only Brownian rotation of the whole particle.
3
 d hydro



B  
 2k B T 


•Since B = 1/fB; DLS size data suggests a relaxation limit fB of 2-3
kHz for FluidmagDX and 300-400 kHz for the dispersed sample.
•Superparamagnetic particles exhibit hysteresis above their
Blocking frequency fB (as well as below their Blocking temperature).
Does this control hyperthermia?
Concentration Effects
•Hyperthermia measurements at
140 kHz were performed on a
range of concentrations of
FluidmagDX.
•The heating rates were
calculated at times less than
300 s
•The heating rate increases
linearly above a low
concentration threshold.
A. Eggemann, et al., IEEE Trans. Mag. 43, 2451-2453 (2007).
Requirements for Hyperthermia
•Model supports linear increase in
heating rate.
•The heating from a single particle
−
is negligible ~10 10 K
•Even a single cluster of
FluidmagDX would only heat by
−8
~10
K
•Effective hyperthermia occurs
when the concentration is ~108
heat sources/cm3
Collective Magnetic Behavior
Fe3O4 nanoparticles developed by: C. Gruettner (Micromod) and R. Ivkov (JHU)
Ref: CL Dennis, AJ Jackson, JA Borchers, PJ Hoopes, R Strawbridge, AR Foreman,
J van Lierop, C Grüttner, and R Ivkov, Nanotechnology, 9 (2009) 395103.
Interaction
peak
SAR
Animal trials by:
P.J. Hoopes and R.
Strawbridge (Dartmouth
College)
Magnetic
structure of
iron oxide core
Decreasing Size
Increasing Angle
Three of the four mice
showed complete
regression of the tumor,
while one mouse had a
highly delayed re-growth.
Strongly interacting coated magnetic
nanoparticles yield very effective
hyperthermia treatments, as compared
with weakly interacting magnetic
nanoparticles.
Animal Tests and Human Trials
Andreas Jordan (Berlin)
- magnetic hyperthermia human
prostate cancer trials
A. Jordan et al., J Magn. Magn. Mater.
194 185-196 (1999).
C. L. Dennis, et al., J. Phys. D:
Appl. Phys. 41 134020 (2008).
http://www.cancer.gov/clinicaltrial
s/
Thanks to Those Who Provided
Slides from Their Work
Masanori Abe – Tokyo Institute of Technology
Natalie Adolphi – Univ. of New Mexico
Hubert Brueckl – ARCS, Vienna
Cindi Dennis – NIST Gaithersburg
Jon Dobson – Keele Univ., UK
Urs Hafeli – Univ. of British Columbia
John Moreland – NIST Boulder
Raju Ramanujan – Nanyang Technological Univ., Singapore
Shan Wang – Stanford Univ.
Next Magnetic Carriers Meeting