Star-shaped polyhedral oligomeric silsesquioxane-polycaprolactone-polyurethane as biomaterials for tissue engineering application

Abstract

Polyhedral oligomeric silsesquioxane (POSS) is a unique molecule that is composed of an inorganic silica core with eight organic functional arms, which can be used as a nucleus for covalent bonding to create star-shaped block copolymers with improved mechanical and biological properties. In this work, highly porous star-shaped POSS-polycaprolactone-polyurethane (POSS-PCL-PU) films were synthesized as scaffold biomaterials for tissue engineering. These films have an interesting morphology consisting of rough spherulites with filamentous structures spreading out from their centers; the unique nanotopography was shown to be suitable for cell growth. In vitro degradation was monitored for 52 weeks in terms of the weight loss and morphology changes of the films. The degradation profile exhibited a slow initial weight loss of <1% during the first 24 weeks, followed by a rapid weight loss of ~18% in the following 28 weeks. The films demonstrated excellent biocompatibility and cell-substrate affinity, with a high cell viability of >95% and rapid cell proliferation. The high porosity, unique surface nanotopography and excellent biocompatibility of the star-shaped POSS-PCL-PU film make it a great candidate as a tissue engineering scaffold biomaterial. Researchers in Singapore have prepared highly porous films that are very promising as scaffold biomaterials for tissue engineering. They synthesized the films by using star-shaped polyhedral oligomeric silsesquioxane as the starting inorganic core and incorporating polycaprolactone (PCL) and polyurethane (PU). The researchers, who are from the Institute of Materials Research and Engineering and the National University of Singapore, demonstrate that the inorganic-organic nanocomposite films satisfy all the key criteria for a biodegradable scaffold biomaterial — they have an excellent biocompatibility, a high porosity and a controlled and slow degradability. In addition, the scientists show that the material's unique nanotopography, which is produced by filamentous structures branching out from the centres of rough spherulites, promotes cell growth. The combination of organic and inorganic functionalities makes these films superior to conventional PCL-PU films. Highly porous star-shaped polyhedral oligomeric silsesquioxane (POSS) hybrid films were synthesized using POSS as the starting core followed by polycaprolactone (PCL) extension and polyurethane (PU) cross-linking. The unique three-dimensional nanotopography of these films is conducive for cell growth. The combination of favorable factors such as high porosity, reactive surface topography, excellent biocompatibility and biphasic degradation makes the star-shaped POSS-PCL-PU film a great candidate as a tissue engineering scaffold biomaterial.