Photo-cross-linked hybrid polymer networks consisting of poly(propylene fumarate) and poly(caprolactone fumarate): Controlled physical properties and regulated bone and nerve cell responses

Aiming to achieve suitable polymeric biomaterials with controlled physical properties for hard and soft tissue replacements, we have developed a series of blends consisting of two photo-cross-linkable polymers: polypropylene fumarate (PPF) and polycaprolactone fumarate (PCLF). Physical properties of both un-cross-linked and UV cross-linked PPF/PCLF blends with, PPF composition ranging from 0% to 100% have been investigated extensively. It has been found that the physical properties such as thermal, rheological, and mechanical properties could be modulated efficiently by varying the PPF composition in the blends. Thermal properties including glass transition temperature (T_g) and melting temperature (T_m) have been correlated with their rheological and mechanical properties. Surface characteristics such as surface morphology, hydrophilicity, and the capability of adsorbing serum protein from culture medium have also been examined for the cross-linked polymer and blend disks. For potential applications in bone and nerve tissue engineering, in vitro cell studies including cytotoxicity, cell adhesion, and proliferation on cross-linked disks with controlled physical properties have been performed using rat bone marrow stromal cells and SPL201 cells, respectively. In addition, the role of mechanical properties such as surface stiffness in modulating cell responses has been emphasized using this model blend system.