Device anchoring of artificial cornea implants, through tissue integration of
stromal tissue, is necessary to ensure long-term success. In this work, the delivery of
basic fibroblast growth factor (FGF-2), a key modulator in corneal wound healing, via
heparin modified materials was investigated as a means of sustained, soluble growth
factor delivery for stimulation of device anchorage. Two materials types, commonly used
for ophthalmic applications and currently under investigation for use in artificial cornea
applications, were utilized. Poly (dimethyl siloxane) (PDMS) is currently under
investigation as the base material for keratoprosthetic devices; dendrimer crosslinked
collagen has been examined as the basis for use as a tissue engineered corneal equivalent.
PDMS surfaces were modified directly or indirectly, through a poly (ethylene
oxide) (PEO) spacer, to contain functionalized reactive NSC groups capable of binding
heparin and FGF-2 Surface modifications were characterized with attenuated total
reflection Fourier transform infrared spectrophotometer (ATR-FTIR), X-ray
photoelectron spectroscopy (XPS) and water contact angles. Heparin coverage was
assessed with metachromatic and bioactivity assays. Heparinized collagen gels were crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and polypropyleneimine octaamine G2 dendrimers. Gel integrity was assessed with water uptake, differential sr::anning calorimetry, and heparin and dendrimer stability. Both materials were exposed to radiolabelled FGF-2 and growth factor
immobilization and delivery were quantified. Heparinized PDMS surfaces were capable
of binding on average 100 ng/cm2 ofFGF-2, while heparinized collagen gels had higher
FGF-2 immobilization, 300 ng, likely attributed to their higher heparin densities and the
fact that the bulk gel rather than the surface only was modified. Delivery of FGF-2 from
the heparinized materials revealed a first order release profile, with an initial burst of
FGF-2, followed by gradual growth factor release. Release rates, over a 2 week period,
reached 6.5% and 50%, for 1 day and 3 day FGF-2 exposed heparinized PDMS modified
surfaces, while hepruinized dendrimer crosslinked collagen gels released 40%. / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/23602 |
| Date | 09 1900 |
| Creators | Princz, Marta A. |
| Contributors | Sheardown, Dr. H., Chemical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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