Uphill production of dihydrogen by enzymatic oxidation of glucose without an external energy source

Engineering bio-interfaces for the direct electron transfer of Myriococcum thermophilum cellobiose dehydrogenase: Towards a mediator-less biosupercapacitor/biofuel cell hybrid

Direct electron transfer (DET) of enzymes on electrode surfaces is highly desirable both for fundamental mechanistic studies and to achieve membrane- and mediator-less bioenergy harvesting. In this report, we describe the preparation and comprehensive structural and electrochemical characterization of a three-dimensional (3D) graphene-based carbon electrode, onto which the two-domain redox enzyme Myriococcum thermophilum cellobiose dehydrogenase (MtCDH) is immobilized. The electrode is prepared by an entirely novel method, which combines in a single step electrochemical reduction of graphene oxide (GO) and simultaneous electrodeposition of positively charged polyethylenimine (PEI), resulting in a well dispersed MtCDH surface. The resulting MtCDH bio-interface was characterized structurally in detail, optimized, and found to exhibit a DET maximum current density of 7.7 ± 0.9 μA cm^-2 and a half-lifetime of 48 h for glucose oxidation, attributed to favorable MtCDH surface orientation. A dual, entirely DET-based enzymatic biofuel cell (EBFC) was constructed with a MtCDH bioanode and a Myrothecium verrucaria bilirubin oxidase (MvBOD) biocathode. The EBFC delivers a maximum power density (P_max) of 7.6 ± 1.3 μW cm^-2, an open-circuit voltage (OCV) of 0.60 V, and an operational lifetime over seven days, which exceeds most reported CDH based DET-type EBFCs. A biosupercapacitor/EBFC hybrid was also constructed and found to register maximum power densities 62 and 43 times higher than single glucose/air and lactose/air EBFCs, respectively. This hybrid also shows excellent operational stability with self-charging/discharging over at least 500 cycles.

Totally implantable enzymatic biofuel cell and brain stimulator operating in bird through wireless communication

Animals digest food to fuel brain neurometabolism via cellular respiration. This study demonstrates the combination of a biofuel cell (BFC) and an animal brain stimulator (ABS) implanted in a pigeon. Glucose oxidation and oxygen reduction in an enzymatic BFC supplied electrical power to the ABS. Power from the BFC reached 0.12 mW in vitro and 0.08 mW in vivo using only the natural glucose and oxygen in the pigeon's body. A power management integrated circuit is used to harvest energy from the in vivo BFC at a rate of 28.4 mJ over 10 min, which is sufficient for intermittent neurostimulation.

Enzymatic regeneration and conservation of ATP: challenges and opportunities

Adenosine triphosphate (ATP), the universal energy currency of life, has a central role in numerous biochemical reactions with potential for the synthesis of numerous high-value products. ATP can be regenerated by three types of mechanisms: substrate level phosphorylation, oxidative phosphorylation, and photophosphorylation. Current ATP regeneration methods are mainly based on substrate level phosphorylation catalyzed by one enzyme, several cascade enzymes, or in vitro synthetic enzymatic pathways. Among them, polyphosphate kinases and acetate kinase, along with their respective phosphate donors, are the most popular approaches for in vitro ATP regeneration. For in vitro artificial pathways, either ATP-free or ATP-balancing strategies can be implemented via smart pathway design by choosing ATP-independent enzymes. Also, we discuss some remaining challenges and suggest perspectives, especially for industrial biomanufacturing. Development of ATP regeneration systems featuring low cost, high volumetric productivity, long lifetime, flexible compatibility, and great robustness could be one of the bottom-up strategies for cascade biocatalysis and in vitro synthetic biology.

Vision Statement: Interactive Materials-Drivers of Future Robotic Systems

A robot senses its environment, processes the sensory information, acts in response to these inputs, and possibly communicates with the outside world. Robots generally achieve these tasks with electronics-based hardware or by receiving inputs from some external hardware. In contrast, simple microorganisms can autonomously perceive, act, and communicate via purely physicochemical processes in soft material systems. A key property of biological systems is that they are built from energy-consuming "active" units. Exciting developments in material science show that even very simple artificial active building blocks can show surprisingly rich emergent behaviors. Active nonequilibrium systems are therefore predicted to play an essential role in realizing interactive materials. A major challenge is to find robust ways to couple and integrate the energy-consuming building blocks to the mechanical structure of the material. However, success in this endeavor will lead to a new generation of sophisticated micro and soft-robotic systems that can operate autonomously.

Physical Chemistry, a Discipline in Its Golden Age

Alexander Kuhn is Full Professor at the Institute of Molecular Science (University Bordeaux, CNRS, Bordeaux INP) as well as Adjunct Professor at VISTEC (Thailand) and Henan University (China). He currently serves as a chair of the ChemPhysChem Editorial Board.

Recent advances in the electrooxidation of biomass-based organic molecules for energy, chemicals and hydrogen production

The recent developments in biomass-derivative fuelled electrochemical converters for electricity or hydrogen production together with chemical electrosynthesis have been reviewed.