Hybrid Amyloid-Based Redox Hydrogel for Bioelectrocatalytic H2 Oxidation.

An artificial amyloid-based redox hydrogel was designed for mediating electron transfer between a [NiFeSe] hydrogenase and an electrode. Starting from a mutated prion-forming domain of fungal protein HET-s, a hybrid redox protein containing a single benzyl methyl viologen moiety was synthesized. This protein was able to self-assemble into structurally homogenous nanofibrils. Molecular modeling confirmed that the redox groups are aligned along the fibril axis and are tethered to its core by a long, flexible polypeptide chain that allows close encounters between the fibril-bound oxidized or reduced redox groups. Redox hydrogel films capable of immobilizing the hydrogenase under mild conditions at the surface of carbon electrodes were obtained by a simple pH jump. In this way, bioelectrodes for the electrocatalytic oxidation of H2 were fabricated that afforded catalytic current densities of up to 270 µA cm-2 , with an overpotential of 0.33 V, under quiescent conditions at 45 °C.

Design of hyaluronan-based dopant for conductive and resorbable PEDOT ink.

Conformable biocompatible conductive materials are increasingly sought for the development of bioelectronics. If additionally resorbable, they could serve for the design of transient implantable electronic devices, opening the way to new healthcare applications. Hyaluronan (HA) derivatives including sulfate and aminophenylboronic acid (PBA) groups (HAS-PBA) were therefore designed to serve as dopants of poly(3,4-ethylenedioxy)thiophene (PEDOT). The optimized HA sulfation protocol allowed good control on polymer sulfation degree while minimizing polymer chain degradation. Sulfated HA was shown to be degradable in physiological conditions. A synergy was observed between the sulfate negative charges and the PBA aromatic groups promoting hydrophobic interactions and π-stacking between PEDOT and HAS-PBA, to boost the material conductivity that reached 1.6 ± 0.2 S/cm in physiological conditions. Moreover the PEDOT:HAS-PBA material was not cytotoxic and could be formulated for easy processing by inkjet printing, appearing as promising candidate for the design of soft transient electronics for in vivo applications.

Ultra-High Tg Thermoset Fibers Obtained by Electrospinning of Functional Polynorbornenes.

Insertion polynorbornenes (PBNEs) are rigid-rod polymers that have very high glass transition temperatures (Tg). In this study, two functional PNBEs were electrospun in the presence of a variety of cross-linkers, resulting in fibers with Tgs greater than 300 °C. The fibers are long (several mm), rigid, and with diameters that can be tuned in the range 300 nm-10 µm. The electrospinning process can be used to encapsulate dyes or graphene dots. Due to the high cross-linking density of the fiber, dye leaching is prevented. In contrast with other rigid-rod polymers, electrospinning of PNBE is facile and can be performed at injection rates as high as 1 mL/min.