Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application
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University of Akron / OhioLINK
2019
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ndltd-OhioLink-oai-etd.ohiolink.edu-akron15553446064844532021-08-03T07:10:19Z Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application Dilla, Rodger Alan Polymer Chemistry Polymers Organic Chemistry Biomedical Research PEG hydrogel tunable modulus tissue engineering additive manufacturing self assembly PEG and PEG-based hydrogels offer many advantages for tissue engineering scaffolds as a consequence of their hydrophilicity, wide range of cross-linking chemistries, low immunogenicity, and tunable mechanical properties. Human mesenchymal stem cells (hMSCs) have demonstrated varying lineage commitment in response to the mechanical and degradation properties of PEG hydrogels within which they were encapsulated. Furthermore, the proliferation and differentiation of pre-osteoblasts have been shown to be influenced by cell scaffold features such as porosity and surface area. Therefore, there is a need to develop materials that provide precise control over mechanical properties and final scaffold morphology to allow for the accurate assessment of material properties on cell behavior. Few hydrogel systems can alter mechanical moduli without changing design elements such as composition, concentration, and stoichiometry. By employing the pH-sensitive kinetics of oxime bond formation, PEG-oxime hydrogels with a shear modulus range of G’ = 5-25 kPa were created from solutions of identical precursor composition, concentration, and stoichiometry simply by varying the pH and buffer concentration of the gelation solution. Equilibrium gel swelling and small angle neutron scattering (SANS) experiments indicated fundamental differences in bond connectivity (i.e. increased loops and dangling ends) were responsible for the observed range in G’. Finally, a 24 h cell viability assay was performed to demonstrate the cell viability of these materials. This study provided important insight in isolating material properties from the chemistry of cross-linking and will inspire further investigations into the effects of material properties on cell behavior.Hydrogel processing is often limited to molding techniques, preventing the formation of complex scaffold morphologies. By utilizing linear PEG as a macro-initiator for the ring opening polymerization of poly(propylene fumarate) (PPF), diblock and triblock copolymer species were synthesized in a series of varying PEG and PPF block lengths which can be photo-crosslinked by the double bonds in PPF. Hydrogels printed by continuous digital light processing (cDLP) additive manufacturing demonstrated a 10-fold increase in extension at break while maintaining the same elastic modulus as those printed from traditional diethyl fumarate (DEF) solutions. High cell viability (> 90%) of three different cell types (nerve, endothelial, and bone) was shown for all PEGPPF hydrogels, demonstrating wide application potential. This system thereby provides handles to tune and investigate both material properties and macroscopic scaffold architecture effects on cell behavior.Finally, the self-assembly of PEGPPF diblock and triblock copolymers were explored as a function of changing solvent identity, initial polymer concentration, and rate of water addition. Resulting particle sizes were observed with Rh ~15-100 nm by DLS and cryo-TEM measurements, and the critical aggregation concentration was estimated by a Nile Red fluorescence assay (~0.14 mg•mL-1 for diblocks, ~0.36 mg•mL-1 for triblocks). Core cross-linking with a photoinitiator was demonstrated, indicating this copolymer system can be utilized to produce robust, stable nanoparticles. 2019-07-16 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1555344606484453 http://rave.ohiolink.edu/etdc/view?acc_num=akron1555344606484453 restricted--full text unavailable until 2021-12-31 This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Polymer Chemistry Polymers Organic Chemistry Biomedical Research PEG hydrogel tunable modulus tissue engineering additive manufacturing self assembly |
| spellingShingle |
Polymer Chemistry Polymers Organic Chemistry Biomedical Research PEG hydrogel tunable modulus tissue engineering additive manufacturing self assembly Dilla, Rodger Alan Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application |
| author |
Dilla, Rodger Alan |
| author_facet |
Dilla, Rodger Alan |
| author_sort |
Dilla, Rodger Alan |
| title |
Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application |
| title_short |
Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application |
| title_full |
Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application |
| title_fullStr |
Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application |
| title_full_unstemmed |
Poly(ethylene glycol)-based Polymers: Synthesis, Characterization, and Application |
| title_sort |
poly(ethylene glycol)-based polymers: synthesis, characterization, and application |
| publisher |
University of Akron / OhioLINK |
| publishDate |
2019 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=akron1555344606484453 |
| work_keys_str_mv |
AT dillarodgeralan polyethyleneglycolbasedpolymerssynthesischaracterizationandapplication |
| _version_ |
1719455115954356224 |