Fast degrading polymer networks based on carboxymethyl chitosan

[EN] In this work macroporous membrane for mesenchymal stem cells, MSCs, transplant has been developed. The membranes support cell seeding and proliferation and completely degrade in less than one week in "in vitro" culture. The biodegradable material is a polymer network based on carboxymethyl chitosan( a water soluble modification of chitosan) crosslinked by poly(epsilon-caprolactone) PCL, fragments which are susceptible to hydrolytic degradation. Synthesis was performed in solution in a common solvent for the two components of the network. The gel fraction was assessed by extraction in selective solvents. Physical characterization of networks of varying composition included water sorption capacity and the crystallinity of poly(epsilon-caprolactone) in the network. In this way polymer networks are synthesized that lose between 66 +/- 5% and 89 +/- 1% of their mass when immersed in water for 28 days. The same weight loss is attained in enzymatic medium in only 4 days. Porcine bone marrow MSCs were seeded in macroporous membranes to show cell viability, and proliferation up to 7 days culture when the biomaterial is completely dissolved in the medium.Gamiz Gonzalez, MA.; Guldrís-Prada, P.; Antolinos Turpín, CM.; Ródenas Rochina, J.; Vidaurre, A.; Gómez Ribelles, JL. (2017). Fast degrading polymer networks based on carboxymethyl chitosan. Materials Today Communications. 10:54-66. doi:10.1016/j.mtcomm.2017.01.005S54661

Influence of the chitosan morphology on the properties of acrylic cements and their biocompatibility

Acrylic bone cements (ABC) are materials widely used in orthopedics and biomedical applications. Several active compounds have been introduced to ABC formulations to improve their mechanical properties and bifunctionality. In this research, we studied the effect of the addition of chitosan (CS) microspheres and chitosan sheets on ABC formulations. For mechanical performance optimization, the compression strength was taken as a response variable using an extreme vertices mixing design with fraction by weight of CS and poly(methyl methacrylate) (PMMA) as the variable factors. According to the statistical analysis, the control samples (without CS), samples with 7% (wt.) of CS sheets, and samples with 17% (wt.) of CS spheres presented the best compression properties: 90.6 MPa and 95.6 MPa, respectively. The study of these formulations confirmed that CS spheres allow a higher amount of loading on the formulation, maintaining comparable compression strength. By 1H-NMR, it was observed that the residual monomer was similar in all wording. The hydrolytic degradation assay in simulated body fluid (SBF) determined that the sphere incorporation increased by 50% and 35% for the water uptake and weight loss values, respectively, when compared with the reported values with CS sheets. By morphological analysis via SEM, it was observed that the porosity increased considerably in the presence of CS spheres throughout the immersion time in SBF. The subdermal implant results demonstrated excellent compatibility between the cement studied and the biological environment.Author Mayra Eliana Valencia Zapata thanks MinCiencias for funding her doctoral studies. Author Luis Rojo is a member of the SusPlast platform from the Spanish National Research Council (CSIC)