Responsive release from a coreshell assembly
Yanjing Chen, Matthew R. Preiss, Arijit Bose, and Geoffrey D. Bothun*
Department of Chemical Engineering
University of Rhode Island
bothun@egr.uri.edu, 401-874-9518
*Associate Professor, Associate Director RI Consortium for Nanoscience and
Nanotechnology (RIN2)
http://www.egr.uri.edu/che/Faculty/Bothun/lab.html
Liposomal release
Leaky enough to allow
release, but not so leaky that
cargo is lost prematurely
•  Limits range of lipids that can
be used
•  Poor stability
L
L
++
++
R∝
++
++
1
DK
∝ Pm =
rb
t
++
++
++
++
++
L
Activation allows release on demand
•  Expands range of lipids that can be
used (e.g. high melting lipids)
•  Improves stability and reduces
leakiness
1 1
+
ra rb
++
L
€
R∝
1 1 1
+ +
ra rb rs
€
2
Liposome-nanoparticle assemblies (LNAs)
dNP < dcore
dNP < ~tb
Core encapsulated
Bilayer embedded
Surface decorated
A
B
C
dNP < dSLB
D1
Nanoparticle ‘activation’
facilitates release
•  Magnetic fields – magnetic
nanoparticles (e.g. Fe3O4)
•  Light – metallic nanoparticles
(e.g. Au)
D2
Complexed
A-1
B-1
B-2
200 nm
C-1
D2-1
D1-1
(A-1) Wijaya & Hamad-Schifferli, Langmuir, 2007, 23
(B-1) Rasch et al, Nano Lett, 2010, 10
(B-2) Chen & Bothun, ACS Nano, 2010, 4
(C-1) Wu et al, J Am Chem Soc, 2008, 130
(D) Volodkin et al, Angew Chem Int Ed, 2009, 48
3
Magnetic nanoparticles & magnetoliposomes
•  Maghemite (γ-Fe2O3) or magnetite (Fe3O4)
−  Small, single domain nanoparticles are superparamagnetic
−  Low toxicity
•  Magnetic drug delivery
•  Magnetic biosensing and diagnostics
Permanent fields
•  MR image contrast agents
•  Nanoparticle-medicated hyperthermia
•  Responsive drug delivery
Alternating fields
De Cuyper & Joniau M, Eur Biophys J, 1988, 15
Soenen et al, Nanomed, 2009, 4
Viroonchatapan et al, J Control Release, 1997, 46
Babincova et al, Bioelectrochemistry, 2002, 55
Pradhan et al, J Control Release, 2010, 142
4
Nanoparticles in EMF fields (at RF)
A: Neel relaxation. Magnetic dipoles change
direction; magnetic losses  heat (< 10-20 nm)
B: Brownian relaxation. Magnetic moment does not
change; frictional losses  heat (> 10-20 nm)
⎛ 2πfτ ⎞
P = πµ0 χ0 H02 f ⎜
2 ⎟
⎝ 1+ (2πfτ ) ⎠
µ0
permeability of free space
χ0
(POWER DISSIPATION
PER VOLUME)
equilibrium susceptibility,
incorporates ρ = φρ N + (1 − φ ) ρ L , cp = φcp,N + (1− φ )cp,L
H0 , f field amplitude and frequency (H = current × # coils per length) €
τ
effective
relaxation time due to Néel and Brownian relaxation
€
€
€
ΔT
P
SAR m NP
=
=
Δt c p ρ
c p mV
Rate of heating of a mass
containing NPs
Laurent et al, Chem Rev, 2008, 108
Mornet et al, J Mater Chem, 2004, 14
Pankurst et al, J Phys D, 2003, 36
5
Local nanoscale heating may not be achievable
•  Water is an excellent heat sink
•  Bilayer thickness yields minimal heat transfer resistance
Ts
T∞ , k,c p
dq
= const
dt
€
dq
dT
λ∇ 2T +
= cp
dt
€ dt
⎛ 1 ⎞ dQ
Ts − T∞ = ⎜⎜
⎟⎟ nano
⎝ 2π krp ⎠ dt
R∝
€
P rp2
Ts − T∞ =
3k
t
k
€
can achieve heating, but local (surface) = bulk
volumetric
€
Keblinski et al, J. Applied Phys, 2006, 100
Gupta et al, J. Applied Phys, 2010, 108
€
6
An example
•  Can local heating be attained in magnetoliposomes (MLs) and measured directly using an
anisotropic fluorescent probe?
12 nm Fe3O4
67% encap.
317 nm dia.
dipalmityolphosphatidylcholine
(DPPC, C16:0)
choline
headgroups
gel phase (T < Tp)
rippled-gel phase (Tp < T < Tm)
fluid phase (T > Tm)
0.35
BBBBBBBBBBB
0.30
DPH anisotropy, <r>
acyl
tails
0.25
J
JJ
J
J
JJJ
JJ
JJJJ
B
B
B
DPPC
BB
B
J
J
BBB
J
J
J
JJJ
J
J
JJJ
J
DPPC + 20 mol%
cholesterol
J
J
JJ
J
0.20
JJ
J
J
J
J
J
J
J
JJJJJJJ
B
JJJ
0.15
0.05
20
J
J
J
J
B
0.10
diphenylhexatriene (DPH)
JJ
BB
B
BB
gel phase
(T < Tm )
25
30
35
40
Temperature,
Bothun & Preiss, J Colloid Interf Sci, 2011, 357
BBB
BB
B
45
BBBB
BBBB
50
J
JJJ
J
JJ
JJ
JJJ
J
fluid phase
(T > Tm )
55
60
oC
7
In situ heating via membrane order, <r>
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Cannot distinguish
between local and bulk
temperatures at the
fluorescence time scale
54
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An approach inspired by biology
Transmembrane proteins
hydrophobic core and
hydrophilic ends
Brownian and
Neel relaxation
Spin/oscillation
Estretch ∝ κ a
d = 6.5 nm
€
Ebend ∝ κ b
adapted from €
Wi et al., J. Phys.: Condens. Matter, 20 (2008) 494211
Y. Chen, A. Bose, G.D. Bothun, ACS Nano 2010, 4(6), 3215-3221
9
Bilayer-embedded SPIO nanoparticles
DPPC
5 nm maghemite (γ-Fe2O3) stabilized in
chloroform with oleic acid (Ocean NanoTech)
B
A
C
1 - 10 mM DPPC
DIUF water
emulsification
REV at 50 oC
450 mbar, 20 min
300 mbar, 20 min
200 mbar, 10 min
10 mM DPPC
DPPC/NP
lipid/NP
10,000:1
(0.9 mM
FemM,
2O3)
2 - 25,000:1
(0.5
5,000:1 (1.8 mM)
0.08 mg/ml Fe2O3)
3 - 10,000:1 (1.2 mM, 0.19 mg/ml)
4 - 5,000:1
Stored
at 50 oC (2.4
(fluid mM,
phase)0.38 mg/ml)
Solvent phase
Dipalmitoylphosphatidylcholine (DPPC)
SPIO NPs (as received and washed)
10
Structure and embedment via cryo-TEM
DPPC
DPPC/NP
25,000:1
ϕNP/L = 0.002
DPPC/NP
10,000:1
ϕNP/L = 0.005
DPPC/NP
5,000:1
ϕNP/L = 0.01
Scale bars = 200 nm
11
Embedded NPs exist partially as aggregates
THINK BIG
WE DO
A
B
C
200 nm
12
Effect of SPIO NPs on DPPC phase behavior
gel phase (T < Tp)
rippled-gel phase (Tp < T < Tm)
fluid phase (T > Tm)
1
50
Cp (KJ/mol.°C)
40
30
2
20
L/N ratio
ΔHm
(KJ/mol)
ΔTm,1/2
(oC)
Control
34.3
1.2
25,000:1
35.7
3.8
10,000:1
37.2
3.5
5,000:1
41.8
5.6
3
4
10
Experiments conducted at
0.1 mM DPPC using a TA
Instruments Nano DSC
0
30
35
40
Temperature (°C)
45
50
13
Controlled release from dMLs
25 oC
diffusing probe (carboxyfluorecein)
CF Leakage (fraction)
1.0
3
0.8
2
0.6
2
4
0.4
1
1
1
2
3
0.2
(1) DPPC
(2) DPPC/NP = 25,000:1
(3) DPPC/NP = 10,000:1
(4) DPPC/NP = 5,000:1
1
2
lipid bilayer
total release
4
0.0
0
1000
2000
3000
1
Time (s)
1
2
14
Enhanced stability & non-invasive
#!!
w/heating,
optimum
1.5
1.0
€
0.5
DPPC/NP = 10,000:1
30 min heating
1!
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Initial leakage rate ( s-1)
2.0
0!
Hf < 4.85x105 kA m-1 s-1
/!
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0.0
0.0
0.5
1.0
1.5
mM Fe2O3
2.0
2.5
w/o heating,
stabilization
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15
Thermomechanical leakage mechanism
τN ~ 1x10-9 s
τB ~ 4x10-7 s
7 nm
w/aggregation, τN decreases
f-1 ~ 3x10-6 s, Neel + Brownian
L/N = 5,000:1
Before heating
L/N = 5,000:1
After heating, 250 A
500 nm
16
Conclusions
•  Small hydrophobic nanoparticle “triggers” can be embedded in lipid
bilayer membranes to control liposomal release
–  May overcome stability limitations and poor cargo delivery
•  Release achieved at non-invasive EMF conditions
–  Transient burst-release mechanism
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•  Functional and stabilizing lipids
•  Cytotoxicity (w/o PEG-lipid shown)
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•  Restructuring due to embedment
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17
Bothun Lab & Collaborators
Graduate Students & Post-docs
Matthew Priess (PhD)
Anju Gupta (PhD)
Qian Ni (MS)
Ashish Airan (MS, Amgen)
David Bello (MS)
Yogi Kurniawan (PhD)
Bastian Weinekotter (MS)
Yanjing Chen (PhD, Post-doc)
Undergraduate Students
Julia Roder-Hanna (ChE, REU)
Mark Bicknell (ChE)
Paul Spinner (ChE)
Eily Cournoyer (ChE)
Jeffrey Hanson (ChE, REU)
Sara Eldridge (ChE)
Ashley Cornell (ChE)
John Alper (ChE)
Sean Marnane (ChE)
Robert DeLuca (CMB)
Summer Interns
Heather Kumar (Eng, CCRI)
Alline Lelis (MB, Providence College)
Amy Rabideau (Chem, Syracuse)
Allison Boyko (HS)
Emily Murphy (HS)
Collaborators
Arijit Bose (URI ChE)
Christopher Kitchens (Clemson U. CBE)
Matthew Stoner (URI BPS)
Robert Hurt (Brown U. Eng.)
Funding
National Science Foundation (CBET 0828022, 0914331)
National Institutes of Health NCRR RI-INBRE
(P20RR016457)
NASA RI Space Grant Consortium
Rhode Island Consortium for Nanoscience and
Nanotechnology (RIN2)