Modulation of Cell Behaviors on Photo-crosslinked Polymer Networks and Polymer Spherulites

This dissertation presents novel biodegradable and photo-crosslinkable poly(-caprolactone) acrylates (PCLAs) to achieve polymer networks with controllable surface chemistry, stiffness, and topographical features, as well as crystallization-induced PCL, poly(3-hydroxybutyrate) (PHB) and poly(L-lactic acid) (PLLA) surfaces for investigating cell-material interactions. Chapter I reviews the recent progress of injectable polymeric biomaterials in the last decade for various tissue engineering applications. Chapter II investigates the variation of thermal and mechanical properties of PCL triacrylate (PCLTA) networks with different crosslinking time, and further studies the smooth muscle cell (SMC) responses to these networks. Chapter III studies the SMC responses to hydrolyzed PCLTA/methoxyl polyethylene glycol monoacrylate (mPEGA) networks, and the in vitro degradation of the crosslinked PCLTA and PCLTA/mPEGA networks. Chapter IV introduces the synthesis, and characterization of four-arm and six-arm PCLAs, and further demonstrates SMC responses to tunable stiffness of the photo-crosslinked PCLA networks. Chapter V investigates the roles of microgroove dimensions in promoting SMC functions on photo-crosslinked PCLA substrates, and further reveals SMC migration can be altered by microgroove dimensions. Chapter VI presents a facile method to synthesize photo-crosslinkable polyhedral oligomeric silsesquioxane (POSS)-PCL diacrylate (POSS-PCLDA) elastomers using POSS as initiator for potential applications in cardiovascular and peripheral nerve regeneration. The crystallinity of PCL network was compressed by POSS molecule, and the amorphous POSSPCLDA networks were elastomeric at physiological temperature. Chapter VII describes the epitaxial crystallization and surface segregation in modulating pre-osteoblastic cell behavior on PCL/PEG substrates. PCL/PEG films had different morphologies on different substrates, and introduced different cell behaviors. Chapter VIII investigates the SMC responses to PHB spherulites. Instead of the banded structures, the cracks on the PHB films were found to be more important in regulating cell alignment. Chapter IX presents the role of PLLA crystallization in regulation cell behaviors. Rougher surfaces of PLLA were found to be worse in supporting cell attachment and proliferation.