Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Hydrogel materials have shown great potential as polymeric scaffolds for soft tissue regeneration, with mechanical and physical properties which can be tailored to a three-dimensional, porous network, similar to the extra cellular matrix.
This project proposes a synthesis route for the formation of bioactive poly (ethylene glycol), PEG, based hydrogels. PEG solely does not promote cell attachment, however, the introduction of bioactive substances enables cell guidance, thereby facilitating and accelerating cell-material interactions.
Dual functional precursor materials, consisting of linear PEG with allyl and azide end-functionality were synthesized and purity was ensured with NMR and MALDI-ToF MS. Bioactive moieties were then introduced by the use of copper catalyzed click-chemistry, CuAAC. An assessment of the copper content in these, biofunctionalized, materials with AAS was also performed, with the aim to ensure a non-toxic environment for in vitro evaluation. The most promising purification methods was found to be a combination of activated neutral aluminum oxide column with leaching of produced gels in EDTA solution.
An initial study was conducted in order to optimize the gelation properties of thiol-ene cured PEG hybrid materials by varying the curing time, wt% of polymeric material and type of cross-linker. The prepared gels were analyzed with RAMAN spectroscopy as well as subjected to a swelling and leaching study. The experimental set-up was then tuned to 30 wt% of dry material as well as a curing time of 30 min (corresponding to a total dosage of 4.05 J/cm2) as these gels showed excellent mechanical properties.
Bioactive hydrogels were successfully produced and analyzed with RAMAN and evaluated by swelling and leaching. Gels containing bioactive compounds were delivered for in vitro evaluation. Furthermore, a second approach for introducing bioactive moieties to hydrogel material was successfully proposed by postfunctionalization of synthesized gels with in situ click-reactions.
Finally a study of the effect of deprotection chemistry and density of cross-linking functionality on hydrogel formation was concluded. Physical and mechanical properties were investigated with RAMAN, swelling, leaching and rheology measurements, suggesting that the degree of tailoring of hydrogel materials can be enhanced to suit the intended application.
2011. , 56 p.