A new biodegradable nanocomposite based on polyhedral oligomeric silsesquioxane nanocages: cytocompatibility and investigation into electrohydrodynamic jet fabrication techniques for tissue-engineered scaffolds.

Our group has developed a non-biodegradable nanocomposite based on POSS (polyhedral oligomeric silsesquioxane) nanocages with PCU [poly(carbonate urethane)] and previous studies have shown good cell-compatibility and antithrombogenic properties. The latest biodegradable formulation is a POSS-modified poly(hexanolactone/carbonate)urethane/urea containing 80% hexanolactone (caprolactone) with the tradename UCL-NanoBio. The direct effect of the polymer on cells was investigated by seeding stem cells on to circular discs of the polymer in 24-well plates; these discs were prepared mainly by electrohydrodynamic jetting. To assess the indirect effect of the polymer, various concentrations of the polymer powder were added to CCM (cell culture medium) and left on a shaker for 10 days. The precipitate was then removed and the CCM was used for culturing the cells seeded on to 24-well plates. Cell viability and growth at 48 and 96 h were assessed using Alamar Blue and lactate dehydrogenase, and morphology was studied by scanning electron microscopy. Cells were shown to adhere well to the polymer, with cell metabolism being comparable with that found on TCP (tissue-culture plastic). Indirect assessment demonstrated some decrease in cell viability with high concentrations of polymer, but showed no difference in cell death between polymer concentrations. The viability of cells seeded on to the polymer was comparable with that of those seeded on to TCP. Cell viability was comparable on both electrosprayed and electrospun scaffolds, but infiltration into the scaffold was much more evident on the electrospun scaffolds. It can be concluded that this new nanocomposite can support the growth and viability of stem cells and that scaffolds of this polymer nanocomposite fabricated by electrohydrodynamic jetting routes have potential use for tissue engineering in the future.