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This work presents the development of an enzyme fuel cell, termed "BioBattery", that utilizes multicopper oxidases as the anodic enzyme in a non-diffusion limited system. We evaluated various enzyme variants as the anode, including multicopper oxidase from Pyrobaculum aerophilum , laccase from Trametes versicolor , and bilirubin oxidase from Myrothecium verrucaria. Several combinations of cathodes were also examined, focusing on the reduction of oxygen as the primary electron acceptor. The optimal pairing used multicopper oxidase from Pyrobaculum aerophilum as the anode and amine reactive phenazine ethosulfate modified bovine serum albumin as the cathode. BioBattery was integrated with our previously developed BioCapacitor, proving capable of consistently powering a 470 μF capacitor, positioning it as a modular power source for wearable and implantable systems. This research work addresses and overcomes some of the fundamental limitations seen in enzyme fuel cells, where power and current are often limited by substrate accessibility to the active electrode surface. (152 words). • A novel enzyme fuel cell, termed "BioBattery" was developed. • BioBattery utilizes multicopper oxidases as the anodic enzyme. • BioBattery delivers continuous, stable power independently of substrate diffusion from the bulk environment. • The optimal BioBattery configuration utilizes an extremophile derived multicopper oxidase. • Successfully integrated the BioBattery with a "BioCapacitor," consistently powering a 470 μF capacitor within 25 s. [ABSTRACT FROM AUTHOR]

Enzymatic biofuel cells can generate electricity directly from the chemical energy of biofuels in physiological fluids, but their power density is significantly limited by the performance of the cathode which is based on oxygen reduction for in vivo applications. An oxygen-independent and membrane-less glucose biobattery was prepared that consists of a dealloyed nanoporous gold (NPG) supported glucose dehydrogenase (GDH) bioanode, immobilised with the assistance of conductive polymer/Os redox polymer composites, and a solid-state NPG/MnO 2 cathode. In a solution containing 10 mM glucose, a maximum power density of 2.3 µW cm −2 at 0.21 V and an open circuit voltage (OCV) of 0.49 V were registered as a biobattery. The potential of the discharged MnO 2 could be recovered, enabling a proof-of-concept biobattery/supercapacitor hybrid device. The resulting device exhibited a stable performance for 50 cycles of self-recovery and galvanostatic discharge as a supercapacitor at 0.1 mA cm −2 over a period of 25 h. The device could be discharged at current densities up to 2 mA cm −2 supplying a maximum instantaneous power density of 676 μW cm −2 , which is 294 times higher than that from the biobattery alone. A mechanism for the recovery of the potential of the cathode, analogous to that of RuO 2 (Electrochim. Acta 42(23), 3541–3552) is described. [ABSTRACT FROM AUTHOR]

• Enzymatic bioelectrode characterized for energy generation and biosensing purposes. • Bilirubin oxidase immobilized on carbon paper using PBSE as bifunctional crosslinker. • Biobattery successfully applied in powering a digital watch for over 2 h. • Biosensor revealed high sensitivity (606 μA mM−1 cm−2) and low LOD (1.3 μM) for O 2. • Response maintained (88%) for 34 days through constant bioelectrode reutilization. Biological systems can be envisaged as energy-sustainable solutions for both microenergy production to power small electronics and sensing purposes. In the present work, an enzymatic bioelectrode was characterized as biocathode in the fabrication of a biobattery and as biosensor for dioxygen detection. Carbon fibre paper was selected as transducer given its unique tailoring and electrocatalytic characteristics, being modified with carbon nanotubes for subsequent attachment of bilirubin oxidase enzyme. The immobilization process was based on a simple but effective method using the crosslinker 1-pyrenebutanoic acid N-hydroxysuccinimide ester, which creates stable bonds by maintaining a good response (88%) for over 34 days. The biobattery, that consisted of a zinc anode coupled with the developed biocathode, produced an open circuit potential of 1.69 V and maximum power of 40 μW, being capable of powering a digital watch for over 2 h. When applied as a dioxygen biosensor, the biocathode revealed high sensitivity of 606 ± 22 μA mM−1 cm−2 and low limit of detection of 1.3 ± 0.2 μM in chronoamperometric measurements at +0.4 V. The application of bilirubin oxidase in the fabrication of biobatteries is scarcely studied even given its advantages over other dioxygen reduction enzymes. Likewise, the use of the remarkable features of CP in dioxygen biosensing is yet to be explored. Therefore, this work stands as an interesting opportunity in the development of relatively simple and affordable bioelectrodes viably intended for energy and biosensing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A water-proof anti-drying enzymatic O 2 cathode for a deformable bioelectric skin patch was developed by laminating a thin membrane (50 μm thick) of polydimethylsiloxane (PDMS) to a bilirubin oxidase (BOD)-modified carbon fabric (CF) electrode. The PDMS membrane and the CF electrode were adhered so that a microspace serving as the oxygen reservoir was formed at their interface, enabling the operation of the patch even in a soaked condition for more than a few minutes. Even if the oxygen in the reservoir was depleted by soaking for too long, the patch performance could be recovered within a few tens of seconds by taking it out of the water, owing to the excellent oxygen-permeability of the thin PDMS membrane. The anti-drying effect of PDMS prolonged the lifetime of the bioelectric patch wrapped around a finger for more than 3 h while maintaining transdermal current of ∼20 μA cm−2. [Display omitted] • A water-proof enzymatic O 2 cathode for a bioelectric skin patch was developed. • A hydrophobic, oxygen-permeable membrane was laminated to the cathode electrode. • The microspace at their interface served as the oxygen reservoir. [ABSTRACT FROM AUTHOR]

Enzymatic biofuel cells are bioelectronic devices that utilize oxidoreductase enzymes to catalyze the conversion of chemical energy into electrical energy. This review details the advancements in the field of enzymatic biofuel cells over the last 30 years. These advancements include strategies for improving operational stability and electrochemical performance, as well as device fabrication for a variety of applications, including implantable biofuel cells and self-powered sensors. It also discusses the current scientific and engineering challenges in the field that will need to be addressed in the future for commercial viability of the technology. [ABSTRACT FROM AUTHOR]

A fully-integrated self-powered system on paper will work independently and self-sustainably as a low-cost and disposable diagnostic device in challenging field conditions such as resource-limited and remote regions. The paper-based power source is essential to create the paper-based system. In this work, a stackable and integrative 3-D paper-based bacteria-powered battery was developed. The battery was capable of generating power from microbial metabolism, delivering on-board energy to the next generation of paper-based systems with one drop of bacteria-containing liquid derived from renewable and sustainable water and wastewater sources (e.g. wastewater, municipal wastes, biomass and watershed) that are readily accessible in the local environment. An inexpensive air-breathing cathode was also created on paper with activated carbon on the sprayed Nickel electrode. By applying origami techniques, compact and stackable 3-D battery structures were created from 2-D sheets through high degrees of folding along pre-defined creases. The bacterial culture was added into two common inlets of the folded battery stack, through which it was transported into each battery. For operation, the battery stack was unfolded to expose all air-cathodes to the air, thereby maximizing their cathodic reactions. [ABSTRACT FROM AUTHOR]

Herein, a fully paper-based biobattery composed of four microbial fuel cell (MFC) units is evaluated, one that can be prepared in advance, stored, and quickly activated with virtually any available fluid. The biobattery uniquely utilizes Bacillus subtilis endospores as the storable anodic biocatalyst; the dormant, robust nature of B. subtilis endospores should allow for device preinoculation with spores followed by prolonged storage of the fully fabricated paper battery until needed. A germinant paper layer strategically fabricated above the spore-loaded anode layer contains all of the necessary chemical germinants and nutrient components required for the endospores to begin germination, exit dormancy, and return to fully metabolic vegetative bacterial cells that can generate electrical energy. This mechanism allows for the battery to be simply initiated via a wide range of available liquids. Bioelectricity generation of the battery is successfully demonstrated after introduction of a variety of artificial bodily fluids, including saliva, sweat, and urine, along with tap water. Since the biobattery has the capability of serially linking all 4 of its MFCs through simple dynamic folding, the device's total power output can be greatly enhanced; a single biobattery is able to achieve 0.56 V and 2.4 μW, which is beyond the ratings required for their intended application in single-use, disposable sensors. Therefore, this concept of integrating 4 spore-based MFCs into a single biobattery device with a built-in germinant layer offers a potential solution for stable, long-term storable power sources, displaying feasibility for integration with low power, disposable sensor applications. [Display omitted] • A fully paper-based, bodily fluid activated biobattery is created. • The biobattery utilizes Bacillus subtilis endospores as the anodic catalyst. • The dormant, robust nature of the endospores allows for storage of the battery. • The battery displays feasibility for integration with sensor applications. [ABSTRACT FROM AUTHOR]

Abstract: Single walled carbon nanotubes (SWCNTs) were equipped with aryl residues by chemical reactions. These insoluble materials were used to substitute classical soluble mediators, which help to transfer electrical charge between the conducting electrode and the redox active center of enzyme molecules. The effect of different aryl residues on the efficiency of the catalytic reduction of dioxygen in the presence of laccase was systematically studied using voltammetry and measuring the power output of a biofuel cell. [Copyright &y& Elsevier]

Abstract: This research focused on the transition of biofuel cell technology to rechargeable biobatteries. The bioanode compartment of the biobattery consisted of NAD-dependent alcohol dehydrogenase (ADH) immobilized into a carbon composite paste with butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid serving as the electrolyte. Ferrocene was added to shuttle electrons to/from the electrode surface/current collector. The bioanode catalyzed the oxidation of ethanol to acetaldehyde in discharge mode. This bioanode was coupled to a cathode that consisted of Prussian Blue in a carbon composite paste with Nafion 212 acting as the separator between the two compartments. The biobattery can be fabricated in a charged mode with ethanol and have an open circuit potential of 0.8V in the original state prior to charging or in the discharged mode with acetaldehyde and have an open circuit potential of 0.05V. After charging it has an open circuit potential of 1.2V and a maximum power density of 13.0μWcm−3 and a maximum current density of 35.0μAcm−3, respectively. The stability and efficiency of the biobattery were studied by cycling continuously at a discharging current of 0.4mA and the results obtained showed reasonable stability over 50 cycles. This is a new type of secondary battery inspired by the metabolic processes of the living cell, which is an effective energy conversion system. [Copyright &y& Elsevier]

Abstract: In this paper, we have established that poly(neutral red), PNR, functions as an electrocatalyst for the reduction and oxidation of NAD+/NADH in a rechargeable biobattery environment. The reversibility of this catalyst was possible only with the addition of Zn2+ for complexation to the redox polymer. The zinc ion complexation with the polymer facilitates electron and proton transfer to/from the substrate and the NAD+/NADH coenzyme without forming covalent bonds between the nicotinamide and the substrate surface. This research presents use of this reversible catalyst in a rechargeable biobattery. The rechargeable battery includes a Prussian blue cathode and a bioanode including NAD+-dependent alcohol dehydrogenase and zinc complexed PNR. This bioanode was coupled to the cathode with Nafion® 212 acting as the ion exchange membrane separator between the two compartments. The biobattery has an open circuit potential of 0.545(±0.009)V when first assembled and 0.053(±0.005)V when fully discharged. However, when fully charged, the biobattery has an open circuit potential of 1.263(±0.051)V, a maximum power density of 16.3(±4.03) μWcm−3 and a maximum current density of 221(±13.2)μAcm−3. The efficiency and stability of the biobattery were studied by cycling continuously at a discharging rate of 1C and the results obtained showed reasonable stability over 50 cycles. [Copyright &y& Elsevier]