Tailored Methodology Based on Vapor Phase Polymerization to Manufacture PEDOT/CNT Scaffolds for Tissue Engineering.

Three-dimensional (3D) scaffolds with tailored stiffness, porosity, and conductive properties are particularly important in tissue engineering for electroactive cell attachment, proliferation, and vascularization. Carbon nanotubes (CNTs) and poly(3,4-ethylenedioxythiophene) (PEDOT) have been extensively used separately as neural interfaces showing excellent results. Herein, we combine both the materials and manufacture 3D structures composed exclusively of PEDOT and CNTs using a methodology based on vapor phase polymerization of PEDOT onto a CNT/sucrose template. Such a strategy presents versatility to produce porous scaffolds, after leaching out the sucrose grains, with different ratios of polymer/CNTs, and controllable and tunable electrical and mechanical properties. The resulting 3D structures show Young's modulus typical of soft materials (20-50 kPa), as well as high electrical conductivity, which may play an important role in electroactive cell growth. The conductive PEDOT/CNT porous scaffolds present high biocompatibility after 3 and 6 days of C8-D1A astrocyte incubation.

Graphene hybrid materials? The role of graphene materials in the final structure of hydrogels.

Graphene (G), graphene oxide (GO) and graphene quantum dots (GQDs) have been introduced into a three-dimensional polymeric network based on polyacrylamide in order to ascertain the role of each nanomaterial in hydrogels. The hydrogel structure is not affected by the introduction of GQDs, since these nanoparticles do not form part of the polymeric network. G and GO modify the structure of the hydrogels but in a different way. GO seems to interact by hydrogen bonding to form non-homogeneous gels in which the mechanical properties are not markedly improved. However, G takes an active part in the formation of the polymeric network, which leads to improved mechanical properties and stability of the final material to give rise to truly hybrid hydrogels and not mere two-phase composite materials.

Graphene Quantum Dot-Aerogel: From Nanoscopic to Macroscopic Fluorescent Materials. Sensing Polyaromatic Compounds in Water.

Fluorescence based on quantum confinement is a property restricted to the nanoscopic range. The incorporation of nanoparticles in a three-dimensional polymeric network could afford macroscopic scaffolds that show nanoscopic properties. Moreover, if these scaffolds are based on strong bonds, the stability of the resulting materials can be preserved, thus enhancing their final applications. We report for the first time the preparation of a graphene quantum dot (GQD) composite based on a cationic covalent network. This new material has unusual features: (i) the final composite remains stable after several swelling-deswelling cycles, thus demonstrating strong interactions between GQDs and the polymeric material, and therefore it could be used as a portable system. (ii) Fluorescence emission in the composite and in solution is quasi-independent to the excitation wavelength. (iii) However, and in contrast to the behavior observed in GQD solutions, the fluorescence of the composite remains unaltered over a wide pH range and in the presence of different ions commonly found in tap water. (iv) Fluorescence quenching is only observed as a consequence of molecules that bear aromatic systems, and this could be applied to the preparation of in situ water sensors.