Self-Healing Hydrogel Films
L. Andrew Lyon, Professor
School of Chemistry and Biochemistry
Petit Institute for Bioengineering and Bioscience
Georgia Institute of Technology
lyon@gatech.edu
lyongroup.net
Lyon Group: Soft Materials Design
!
Delivery Vehicles:
- Targeting
- Encapsulation/Release
- Particle Erosion
- Protein-Particle
Interactions
- Bioconjugation
Chemistries
Thin Films:
- Coating Methods
- Dynamic Films
- Protein & Cell Interactions
- Biomaterials
Microgel Phases:
- Dynamic Assemblies
- Physics of Softness
- Protein-Mediated
Assembly
Microgel-Based Thin Films
Motivation: Design of dynamic, responsive, and
multicomponent interfaces.
release
(elution, erosion)
triggered display
protein resistance
Phase Separation-Mediated
Synthesis
Microgel formation via precipitation polymerization
nucleation
growth via nuclei aggregation,
monomer and oligomer capture
Thin Film Self-Assembly
+ +
+
+
- - - - - - - - SUBSTRATE
1)  Polyanion
2)  rinse
+ + + + + +
- - - - - - - - SUBSTRATE
1)  Polycation
2)  rinse
- - - - - - - - SUBSTRATE
For a recent review on microgel assemblies, see:
Lyon, L. A.; Meng, Z. Y.; Singh, N.; Sorrell, C. D.; John, A. S., Chem. Soc. Rev. 2009, 38 (4), 865-874.
Thin Film Self-Assembly
For a recent review on microgel assemblies, see:
Lyon, L. A.; Meng, Z. Y.; Singh, N.; Sorrell, C. D.; John, A. S., Chem. Soc. Rev. 2009, 38 (4), 865-874.
Modulating Inflammation
cytokines
macrophages
fibrous capsule
FBGC
t < 1 min
t ~ hr
t ~ days
t ~ wks
During wound healing, foreign bodies suffer from protein & cell
adhesion, followed by fibrosis, limiting device performance.
Anderson JM, Ann. Rev. Mater. Res. (2001)
Ratner BD & Bryant SJ, Ann. Rev. Biomed. Eng. (2004)
Non-Fouling Microgels
>31 ºC the pNIPAm-rich segments desolvate and the PEG
segments become more surface localized.
Gan, D.; Lyon, L. A. Macromolecules 2002, 35, 9634-9639.
Nolan, C. M.; Reyes, C. D.; Debord, J. D.; García, A. J.; Lyon, L. A. Biomacromolecules 2005, 6, 2032-2039.
Protein-Resistant Microgel Monolayers
Bare PET
Microgel coating
Bare PET
Reduced chronic
inflammation
Reduced acute
inflammation
Microgel Coating
50 µm
Bridges, A. W.; Singh, N.; Burns, K. L.; Babensee, J. E.; Lyon, L. A.; Garcia, A. J., Biomaterials 2008,
29, 4605-4615.
Bridges, A. W.; Whitmire, R. E.; Singh, N.; Templeman, K. L.; Babensee, J. E.; Lyon, L. A.; Garcia, A. J.,
J. Biomed. Mater. Res., Part A 2010, 94A, 252-258.
Application: Reconstructive Surgery
A wide range of biomaterial implants are
currently used in cosmetic and reconstructive
arenas: chin, calf, buttock, breast, etc.
All potentially suffer from poor integration or
rejection.
Biomaterial needs: non-inflammatory, pro
wound healing, stability, surgical compatibility.
Coating Silicone Rubber
Miniature silicone implant
HCl
treatment*
-- -
-- - -- -- - NH OH NH NH OH NH OH NH
+
3
+
3
+
3
*Huang, H.; Chung, J. Y.; Nolte, A.
J.; Stafford, C. M. Chem. Mater.,
2007, 19, 6555-6560.
+
3
+
3
OH OH OH OH OH OH OH OH
Aminopropyl
(trimethoxy silane)
treatment
Microgel
deposition
NH3+ OH NH3+ NH3+OH NH3+OH NH3+
Multilayer Coatings on Silicone
-- -
-- - -- -- - Covalent attachment
NH OH NH NH OH NH OH NH
+
+
3
3
-- -
----
-
+
3
+
3
-- - --- - -- - --- - --
+
3
(EDC/NHS)
-
-
-- -
-- - -- -- - p(DADMAC) (Poly
(diallyl dimethyl
ammonium chloride))
Repeat
-- -
Microgel
deposition
-- - -- -- - -
Multilayer Coatings on Silicone
Multilayer Film Structure
Sorrell, C. D.; Lyon, L. A., J. Phys. Chem. B 2007, 111 (16), 4060-4066.
Serpe, M. J.; Lyon, L. A., Chem. Mater. 2004, 16 (22), 4373-4380.
Multilayer Film Structure
= Polycation
= Polyanionic
Microgel
Sorrell, C. D.; Lyon, L. A., J. Phys. Chem. B 2007, 111 (16), 4060-4066.
Serpe, M. J.; Lyon, L. A., Chem. Mater. 2004, 16 (22), 4373-4380.
Problem: Surgeons are not
Delicate
Does surgical handling damage the multilayer coating?
Microgel Multilayers
photo
2.5 mm
optical
microscopy
20 µm
AFM
A plastic pipette tip is
used to damage a
coating on PDMS.
Damage is healed
immediately upon
water immersion.
10 µm
South, A. B.; Lyon, L. A., Angew. Chem., Int. Ed. 2010, 49 (4), 767-771.
Repetitive Damage and Healing
Controlling Toughness:
Nanocomposites
Swelling of the film in a dispersion of anionic gold nanoparticles
(~15-nm diameter) results in absorption of the Au via
Coulombic interactions.
Park, C. W.; South, A. B.; Hu, X.; Verdes, C.; Kim, J.-D.; Lyon, L. A., Colloid Polym. Sci. 2011, 289 (5-6), 583-590.
Microgel
Monolayer
7.5 Bilayers
7.5 Bilayers
+ AuNPs
Concentrationdependent Au
incorporation
Homogeneous Au Incorporation
Well-defined
plasmon
Uniform Fluorescence
Quenching
Native Films: Strain
Dependence
Increased strain induces
higher fracture/wrinkle
frequency with larger zscale deformation.
AuNP
Toughening
Increasing the Au
content decreases the
magnitude and spatial
frequency of damage
events.
Self-healing is
maintained.
Toughening Mechanisms
AuNPs potentially provide:
- Reversible anion-cation
interactions (sacrificial
bonds)
- Defect filling capabilities
Park, C. W.; South, A. B.; Hu, X.; Verdes, C.; Kim, J.-D.; Lyon, L. A., Colloid Polym. Sci. 2011, 289 (5-6), 583-590.
Conclusions