Two blue multicopper oxidases (MCOs) (viz. Trametes hirsuta laccase (ThLc) and Myrothecium verrucaria bilirubin oxidase (MvBOx)) were immobilized on bare polycrystalline gold (Au) surfaces by direct adsorption from both dilute and concentrated enzyme solutions. The adsorption was studied in situ by means of null ellipsometry. Moreover, both enzyme-modified and bare Au electrodes were investigated in detail by atomic force microscopy (AFM) as well as electrochemically. When adsorbed from dilute solutions (0.125 and 0.25 mg mL −1 in the cases of ThLc and MvBOx, respectively), the amounts of enzyme per unit area were determined to be ca. 1.7 and 4.8 pmol cm −2 , whereas the protein film thicknesses were determined to be 29 and 30 Å for ThLc and MvBOx, respectively. A wellpronounced bioelectrocatalytic reduction of molecular oxygen (O 2 ) was observed on MvBOx/Au biocathodes, whereas this was not the case for ThLc-modified Au electrodes (i.e., adsorbed ThLc was catalytically inactive). The initially observed apparent k cat app values for adsorbed MvBOx and the enzyme in solution were found to be very close to each other (viz. 54 and 58 s −1

This work provides an overview of the recent advances in the field of tear‐based wearable electrochemical biodevices, including non‐invasive biosensors, biological fuel cells and biosupercapacitors. Contact lenses are attractive platforms for fabricating non‐invasive self‐contained gadgets for different applications, starting from devices with casual or mundane purposes only, like personalized smart lenses with direct (invisible for others) displays, and ending with biomedical devices for continuous fitness status and/or health care monitoring. Key requirements and challenges that confront researchers in this exciting area are discussed.

Two‐in‐one: A biological supercapacitor—a combination of an electrochemical capacitor and an enzymatic fuel cell—is presented. Both the capacitor and the biofuel cell are built from nanomaterials, namely, polyaniline/carbon nanotube composites and redox enzyme/gold nanoparticle assemblies. The biosupercapacitor is self‐charging, membrane‐ and mediator‐less.

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The concept of supercapacitive photo‐bioanode and biosolar cell (photo‐biosupercapacitor) for simultaneous solar energy conversion and storage is demonstrated for the first time. Exploiting the capacitive component significantly improves the electron transfer processes and allows the achievement of a current density of 280 µA cm−2 in the pulse mode.

We propose the very first “Nernstian biosupercapacitor”, a biodevice based on only one redox polymer: poly(vinyl imidazole‐co‐allylamine)[Os(bpy)2Cl], and two biocatalysts. At the bioanode PQQ‐dependent glucose dehydrogenase reduces the Os3+ moieties at the polymer to Os2+ shifting the Nernst potential of the Os3+/Os2+ redox couple to negative values. Concomitantly, at the biocathode the reduction of O2 by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os2+ to Os3+ shifting the Nernst potential to higher values. Despite the use of just one redox polymer an open circuit voltage of more than 0.45 V was obtained during charging and the charge is stored in the redox polymer at both the bioanode and the biocathode. By connecting both electrodes via a predefined resistor a high power density is obtained for a short time exceeding the steady state power of a corresponding biofuel cell by a factor of 8.

Integrating photosynthetic cell components with nanostructured materials can facilitate the conversion of solar energy into electric power for creating sustainable carbon-neutral energy sources. With the aim at exploring efficient photoinduced biocatalytic energy conversion systems, we have used an amidated carbon nanotube (aCNT) networked matrix to integrate thylakoid membranes (TMs) for construction of a direct electron transfer-driven biosolar cell. We have evaluated the resulting photobioelectrochemical cells systematically. Compared to the carboxylated CNT (cCNT)-TMs system, the aCNT-TMs system enabled a 1.5-fold enhancement in photocurrent density. This system offers more advantages including a reduced charge-transfer resistance, a lower open-circuit potential, and an improved cell stability. More remarkably, the average power density of the optimized cells was 250 times higher than that of reported analogue systems. Our results suggest the significance of physical and electronic interactions between the photosynthetic components and the support nanomaterials and may offer new clues for designing improved biosolar cells.

Hybrid electric power biodevices, a new type of electric‐power‐producing device, are a combination of an electrochemical capacitor and a biofuel cell. In this Minireview, we summarise existing knowledge on double‐function bioelectrodes, that is, single electrodes concurrently manifesting bio‐electrocatalytic and charge‐storage features, and describe important historical aspects and achievements in this area. We also discuss a recently proposed method for concomitant electric power generation and storage, which is exemplified by fabricated and characterised self‐charging bio‐supercapacitors, also termed charge‐storing biofuel cells. The electric power in these hybrid devices is uninterruptedly generated by direct transformation of chemical energy into electric energy, as occurs in biofuel cells. The power is simultaneously and directly stored within a single device, relying on different types of capacitance based on reversible charge‐transfer reactions (pseudocapacitance) and/or electric double‐layer capacitance, as in electrochemical capacitors. We also present some unpublished results on both dual‐feature electrodes and hybrid biodevices and briefly highlight the prospects for their application.