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Stem cell-based therapies have shown promising results for the regeneration of the nervous system. However, the survival and integration of the stem cells in the neural circuitry is suboptimal and might compromise the therapeutic outcomes of this approach. The development of functional scaffolds capable of actively interacting with stem cells may overcome the current limitations of stem cell-based therapies. In this study, three-dimensional hydrogels based on graphene derivatives and cerium oxide (CeO2) nanoparticles are presented as prospective supports allowing neural stem cell adhesion, migration and differentiation. The morphological, mechanical and electrical properties of the resulting hydrogels can be finely tuned by controlling several parameters of the self-assembly of graphene oxide sheets, namely the amount of incorporated reducing agent (ascorbic acid) and CeO2 nanoparticles. The intrinsic properties of the hydrogels, as well as the presence of CeO2 nanoparticles, clearly influence the cell fate. Thus, stiffer adhesion substrates promote differentiation to glial cell lineages, while softer substrates enhance mature neuronal differentiation. Remarkably, CeO2 nanoparticle-containing hydrogels support the differentiation of neural stem cells to neuronal, astroglial and oligodendroglial lineage cells, promoting the in vitro generation of nerve tissue grafts that might be employed in neuroregenerative cell therapies., This work has been funded by the Basque Government (GV/EJ) Department of Education (GIC21/131 IT1766-22, IT1751-22), Health Department (RIS3, 2021333012), Grants PID2019-106236GB-I00 and PID2019-104766RB-C21 funded by MCIN/AEI/10.13039/501100011033. Grant RYC-2013-13450 funded by MCIN/AEI/10.13039/501100011033 and by “ESF investing in your future” by the “European Union” and Achucarro Seed-Fund 003 (JRP), the University of the Basque Country (UPV/EHU) by GIU19/040, GIU 20/050, PPGA 20/22, COLAB19/03 and IKERTU-2020.0155. GV/EJ, Hazitek ZE-2019/00012-IMABI and ELKARTEK KK-2019/00093. Polimerbio and Y. P. have a Bikaintek PhD grant (20-AFW2-2018-00001). Part of this research was performed within the framework of the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 793644 (BIONICS).

Poly(ε-caprolactone) (PCL) was mixed with submicron particles of barium sulfate to obtain biodegradable radiopaque composites. X-ray images comparing with aluminum samples show that 15 wt.% barium sulfate (BaSO4) is sufficient to present radiopacity. Thermal studies by differential scanning calorimetry (DSC) show a statistically significant increase in PCL degree of crystallinity from 46% to 52% for 25 wt.% BaSO4. Non-isothermal crystallization tests were performed at different cooling rates to evaluate crystallization kinetics. The nucleation effect of BaSO4 was found to change the morphology and quantity of the primary crystals of PCL, which was also corroborated by the use of a polarized light optical microscope (PLOM). These results fit well with Avrami–Ozawa–Jeziorny model and show a secondary crystallization that contributes to an increase in crystal fraction with internal structure reorganization. The addition of barium sulfate particles in composite formulations with PCL improves stiffness but not strength for all compositions due to possible cavitation effects induced by debonding of reinforcement interphase. The work was financially supported by funding from the Basque Government Department of Education, Linguistic Politics and Culture for a consolidated research group project IT-927-16 and the Spanish Government´s MINECO MAT2016-78527-P (AEI/FEDER,UE). H.A. thanks the predoctoral grant received from the University of the Basque Country (UPV/EHU).

There is a great interest in incorporating catechol moieties into polymers in a controlled manner due to their interesting properties, such as the promotion of adhesion, redox activity or bioactivity. One possibility is to incorporate the catechol as end-group in a polymer chain using a functional initiator by means of controlled polymerization strategies. Nevertheless, the instability of catechol moieties under oxygen and basic pH requires tedious protection and deprotection steps to perform the polymerization in a controlled fashion. In the present work, we explore the organocatalyzed synthesis of catechol end-functional, semi-telechelic polylactide (PLLA) using non-protected dopamine, catechol molecule containing a primary amine, as initiator. NMR and SEC-IR results showed that in the presence of a weak organic base such as triethylamine, the ring-opening polymerization (ROP) of lactide takes place in a controlled manner without need of protecting the cathechol units. To further confirm the end-group fidelity the catechol containing PLLA was characterized by Cyclic Voltammetry and MALDI-TOF confirming the absence of side reaction during the polymerization. In order to exploit the potential of catechol moieties, catechol end-group of PLLA was oxidized to quinone and further reacted with aliphatic amines. In addition, we also confirmed the ability of catechol functionalized PLLA to reduce metal ions to metal nanoparticles to obtain well distributed silver nanoparticles. It is expected that this new route of preparing catechol-PLLA polymers without protection will increase the accessibility of catechol containing biodegradable polymers by ROP. This work was supported by Basque Government (GV/EJ) Department of Education (IT-927-16), The European Commission support through the project SUSPOL-EJD 64267 and the Gobierno Vasco/Eusko Jaurlaritza (IT 999-16 and IT-618-13). Haritz Sardon gratefully acknowledges financial support from MINECO through project SUSPOL and FDI 16507. Christophe Detrembleur thanks the "Fonds de la Recherche Scientifique" (FRS-FNRS) and the Belgian Science Policy in the frame of the Interuniversity Attraction Poles Program (P7/05)-Functional Supramolecular Systems (FS2) for financial supports. Christophe Detrembleur is Research Director by the FRS-FNRS. Nerea Sadaba is thankful for the predoctoral fellowship to POLYMAT Fundazioa-Basque Center for Macromolecular Design and Engineering.