Towards a new generation of non-cytotoxic shape memory thermoplastic polyurethanes for biomedical applications

In recent decades, the technology of polymeric materials used in biomedical applications has been greatly improved, replacing the metals that had been used until now. This change has not only meant an improvement in the cost of the raw material and in its processing, but it is also due to the fact that there are applications, such as stents, where the material is required to have a certain flexibility, both during the surgical intervention and during the healing or conditioning the tissue in which the intervention is performed. In this type of application, the so-called shape memory polymers (SMPs) are very interesting, but for this, they must meet the condition of being biocompatible. In this work, new polyurethane materials have been designed in which, in addition to shape memory prevailing, adequate cell proliferation values are obtained for possible use in biomedical applications. Furthermore, during the synthesis, in order to avoid undesired and toxics subproducts, instead of the typical aromatic diisocyanates, an aliphatic 1,6-hexamethylene diisocyanate (HDI) has been selected. Moreover, neither solvents nor catalysts were used, which makes eco-friendly synthesis suitable for scaling at an industrial level. Finally, castor oil (CO) has been used as one of the main synthesis reagents, which is an abundant compound obtained from biological sources. For all this, it can be concluded that the polymers described here have a wide range of application possibilities (biomedicine, food packaging…), and are highly interesting to preserve our Planet.