No abstract

No abstract

No abstract

The success of Tissue Engineering (TE) based approaches is strongly dependent on the development of novel biomaterials for the design of 3D matrices with tailored biomechanical properties to promote the regeneration of human tissues and organs. This review covers the critical aspects related with the preparation of new unsaturated polyester (UP) resin formulations with suitable biological, chemical, thermal and morphological properties for the additive manufacturing (AM) of TE constructs. In this context, the basic principles of available AM technologies, with a special focus on novel stereolithography processes such as microstereolithography (micro-SLA), stereothermal-lithography (STLA), two-photon polymerization (TPP) and nanostereolithography (nano-SLA), are also presented and discussed. Ultimately, the present review will provide a better insight into the limitations and potential of combining UP and AM towards the rationale design/fabrication of complex artificial tissue substitutes.

New shape-memory materials (SMMs) for applications in active control and morphing structures have been attracting special attention due to its unique properties. These SMM can be metallic alloys (SMAs), piezoelectric, and polymers such as polyurethanes (SMPUs). The latter detain higher recovery rates but better processability, however, the reaction time is longer when compared with the SMA. The addition of carbon nanotubes (CNTs) to SMPU seems to improve its overall properties with a great deal of potential in what concerns improved shape memory. There are two main techniques to attain SMPU/CNts nanocomposites: in situ polymerization and mechanical melt mixing. The study here presented establishes a comparison between these two techniques. To assess the suitability of the latter a rather extensive characterization was carried out. The homogeneity of the CNTs dispersion into the polymer matrix was established through SEM and the thermal characterization has shown a rise in the glass transition temperature consistent with CNT loading. Furthermore, shape memory seems to improve with the nanoparticle reinforcement. Within the two processing techniques it could be referred that melt processing seems to be simpler to use with better laboratory repeatability, thus detaining a greater potential should nanocomposite tailoring at a larger scale be envisaged.

New micro three-dimensional (3D) scaffolds using biobased unsaturated polyesters (UPs) were prepared by microstereo-thermal-lithography (μSTLG). This advanced processing technique offers indubitable advantages over traditional printing methods. The accuracy and roughness of the 3D structures were evaluated by scanning electron microscopy and infinite focus microscopy, revealing a suitable roughness for cell attachment. UPs were synthesized by bulk polycondensation between biobased aliphatic diacids (succinic, adipic and sebacic acid) and two different glycols (propylene glycol and diethylene glycol) using fumaric acid as the source of double bonds. The chemical structures of the new oligomers were confirmed by proton nuclear magnetic resonance spectra, attenuated total reflectance Fourier transform infrared spectroscopy and matrix assisted laser desorption/ionization-time of flight mass spectrometry. The thermal and mechanical properties of the UPs were evaluated to determine the influence of the diacid/glycol ratio and the type of diacid in the polyester's properties. In addition an extensive thermal characterization of the polyesters is reported. The data presented in this work opens the possibility for the use of biobased polyesters in additive manufacturing technologies as a route to prepare biodegradable tailor made scaffolds that have potential applications in a tissue engineering area.

No abstract

No abstract