Biodegradable Nano-Hybrid Polymer Composite Networks for Regulating Cellular Behavior

Photo-crosslinkable polymeric biomaterials have emerged in the field of biomedical research to promote tissue regeneration. For example, scaffolds that can be crosslinked and hardened in situ have been known to make suitable implant alternatives. Since injectable and photo-crosslinkable biomaterials offer the advantage of being minimally invasive, they have emerged to compete with autografts, a current highly invasive method to repair diseased tissue. A series of novel photo-crosslinkable, injectable, and biodegradable nano-hybrid polymers consisting of poly(ε-caprolactone fumarate) (PCLF) and polyhedral oligomeric silsesquioxane (POSS) has been synthesized in our laboratory via polycondensation. To engineer the material properties of the nano-hybrid networks, varied weight compositions of POSS (ϕ_POSS) were combined with PCLF. The material properties of uncrosslinked and crosslinked PCLF-co-POSS samples were characterized by gel permeation chromatography, thermogravimetric analysis, dynamic mechanical analysis, and differential scanning calorimetry. Surface properties were also analyzed via the water contact angle. From the analysis, we have found that higher weight percentages of POSS resulted in higher stiffnesses and thermal degradation temperatures, but lower crystallinities. Further, PCLF-co-POSS (ϕ_POSS =5%, 10% and 20%) samples had higher wettability, as indicated by smaller water contact angles. The increase in wettability was likely due to POSS’s ability to enhance porosity. To enhance the study for bone repair applications, the PCLF-co-POSS (ϕ_POSS =20%) nanocomposite was supplemented with 20% hydroxyapatite (HA) nanoparticles and formed into disks with smooth and microgrooved surfaces. By tailoring PCLF-co-POSS material properties, substrates can be engineered to entice attachment, proliferation, and differentiation of mouse pre-osteoblastic MC3T3-E1 cells and rat primary aortic smooth muscle cells, targeting for bone and cardiovascular tissue engineering applications.