P1250095226HAmdq

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NIRT Biomimetic Nanostructured Medical
Adhesives CBET 0609182 Edwin P. Chan,
Alborz Madhavi, Lino Ferreira, Jason Nichol,
Jeffrey Karp Robert Langer (PI), Joseph
Vacanti(co-PI), David Carter (co-PI), Jeffrey
Borenstein (co-PI)
Motivation There is significant medical need to
develop a tough, biodegradable adhesive that can
attach strongly to tissue, yet still accommodate
the mechanical deformations present. This
material would be useful as replacement or
support for sutures and/or patches to aid in
hemostasis. The current medical adhesives are
limited in applications due to insufficient
mechanical properties, difficulty in application
and/or non-tailored degradation rates with the
healing time of the tissue.
Bioadhesive Fabrication
Poly(glycerol-sebacate-acrylate) (PGSA) Elastomer

• Polycondensation
• of PGS

• Acrylation of PGS

Approach - Inspirations from Nature
Tissue adhesion Oxidized dextran (DextOx) is used
to enhance PGSAs surface chemical properties. As
in other oxidized polysaccharides,
the aldehyde groups
in DextOx react with
protein amine and forms
imine bond. The
biocompatibility and
biodegradability of DextOx makes it
relevant for tissue
interfacing.
Gecko adhesion The footpad of many insects and
lizards are decorated with fibrillar structures
called setae. Previous work has demonstrated that
the mechanisms of adhesion include the coupling
of wan der Waals attraction and pattern geometry
in tuning interfacial strength.
Nanopatterned PGSA Elastomer
1. Fabricate silicon template by photolithography
and reactive-ion etching
2. Nanomold the PGSA prepolymer with template and
photocure prepolymer
3. Remove PGSA elastomer from template to
generate the nanopatterned PGSA adhesive
A Gecko-inspired Bioadhesive Here, we combine the
design strategies of the gecko (that provides
enhanced dry adhesion by surface patterns) and
incorporate covalent surface chemistry to develop
a new type of solid-state bioadhesive with
tailored interactions with tissue.
Aldehyde chemistry for tissue adhesion
4. Spin-coat DextOx onto PGSA elastomer to
generate the final tissue adhesive
Nanopatterns to enhance mechanical compliance
with tissue
Bioadhesive Performance
Tuning Mechanical Properties The Youngs modulus
and toughness of the material can be easily tuned
by the incorporation of the acrylate side groups
that provides the functionality for forming a
crosslinked network.
Adhesion Testing To simulate the interaction of
the bioadhesive to tissue, we measured the
adhesion of the materials in aquesous conditions.
Additionally, to mimic the mechanical stresses
experienced by the adhesive, we used a
shear-based adhesion tests to replicate the
biological conditions.
0.8 acrylation PGSA
0.3 acrylation PGSA w/ 5 PEG
Porcine intestine tissue
In-vitro testing
0.3 acrylation PGSA
Bioadhesive
Biocompatibility

• Milestones
• Developed a biodegradable, biocompatible
  adhesive with tailored interactions with tissue
• Created a general methodology to nanopattern and
  surface modify the bioadhesive
• Examined the degradation characteristics of the
  material
• Performed adhesion testing of the bioadhesive
• In-progress
• In-vivo testing of bioadhesive in small animal
  models

Cell adhesion proliferation
Biodegradation response
Fibroblast spreading
Confluent cell layer