Two series of segmented polyurethanes were obtained and their mechanical and thermal properties as well as their biodegradability and cytotoxicity were evaluated. The chemical nature of the polyurethanes was varied by using either 1,4 butanediol (poly-ester-urethanes, PEUs) or l-lysine ethyl ester dihydrochloride (poly-ester-urea-urethanes, PEUUs) as chain extenders. Results showed that varying the hard segment influenced the thermal and mechanical properties of the obtained polymers. PEUs showed strain and hardness values of about 10–20 MPa and 10–65 MPa, respectively. These values were higher than the obtained values for the PEUUs due to the phase segregation and the higher crystallinity observed for the polyester-urethanes (PEUs); phase segregation was also observed and analyzed by XRD and DSC. Moreover, both series of polymers showed hydrolytic degradation when they were submerged in PBS until 90 days with 20% of weight loss. In vitro tests using a Human Osteoblastic cell line (Hob) showed an average of 80% of cell viability and good adhesion for both series of polymers.

Degradable poly(ester urethane)s (PEUS)/nanosilica composites are prepared, and a preliminary evaluation of their potential to be used in calcified tissue regeneration is performed. First, poly(ethylene glycol succinate) (PEGS) of different molecular weights is prepared and then a prepolymer with an excess of 1,6-hexamethylene diisocyanate is synthesized; this prepolymer is subsequently extended with 1,4-butanediol in the presence of nanosilica particles. The effects of the structures of PEGS and PEUS are studied by means of attenuated total reflectance infrared, gel permeation chromatography, X-ray diffraction, thermogravimetric analysis, optical microscopy, and scanning electron microscopy. The materials show that similar crystalline structure independently of the molecular weight, however, increases the thermal resistance with higher molecular weight of nanocomposites. After soaking in simulated body fluid, the appearance of apatite phosphate bands in Fourier transformed infrared spectra suggests the bioactive character of these composites. In addition, degradation and toxicity test are performed. The materials are degradable but not cytotoxic after 7 days of testing.

Organic-inorganic hybrid materials are known for their outstanding chemical and physical properties. Although someud studies have been published regarding the use of hybrids for biomedical applications, relationship between hydrophilicud character and biodegradation, bioactivity and biocompatibility has not been studied yet. The sol–gel method has been chosenud for the manufacturing of siloxane-polyurethane hybrids for the exceptional potential of the method to obtain nanostructuredud materials. The effect of the amount of the urethane oligomer (OPU) on the structure, hydrophilic character, degradability,ud bioactivity and citotoxicity was investigated. Gelling time of these hybrids increases linearly with the decrease on theud Siloxane/OPU ratio up to an 80/20 value. Hydrophilic character of the hybrids can be modulated and affects dramaticallyud the degradation rate of the specimens. A hybrid with a 50/50 Siloxane/OPU ratio displayed an appropriate degradationud rate, bioactivity and lack of cell toxicity that makes this material a candidate for further studies for applications in boneud regeneration.Peer reviewe