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Cellobiose dehydrogenase (CDH) is a versatile bioelectrocatalyst lately at focus due to its sugar oxidising properties in combination with its inherent ability for direct electron transfer communication with electrodes making it possible to be used in bioanodes in the enzymatic fuel cells (EFCs), self-powered biosensors, and biosupercapacitors. During the last 20 years, many new nanomaterials and hybrid nanocomposites have been developed and employed in combination with various oxidoreductases, such as CDH, to increase the overall performance of electrical devices (e.g. biosensors, EFCs etc.). It has also been shown that nanomaterials can be further chemically modified to facilitate electron transfer pathways between the biocomponent and electrodes. Both carbon and metal based nanomaterials and combinations thereof have been used together with CDH to improve the performance. In this review, we resume all the findings related to the influence of effective nanostructuration to improve the electron transfer communication with electrodes yielding higher sensitivity of biosensors or increasing the power output of EFC based on CDH from different sources.

Special Issue: Thematic Issue: From complex waste to plastic value., Laccases are multicopper containing enzymes capable of performing one electron oxidation of a broad range of substrates. Using molecular oxygen as the final electron acceptor, they release only water as a by‐product, and as such, laccases are eco‐friendly, versatile biocatalysts that have generated an enormous biotechnological interest. Indeed, this group of enzymes has been used in different industrial fields for very diverse purposes, from food additive and beverage processing to biomedical diagnosis, and as cross‐linking agents for furniture construction or in the production of biofuels. Laccases have also been studied intensely in nanobiotechnology for the development of implantable biosensors and biofuel cells. Moreover, their capacity to transform complex xenobiotics makes them useful biocatalysts in enzymatic bioremediation. This review summarizes the most significant recent advances in the use of laccases and their future perspectives in biotechnology., We recognize the much appreciated financial support of the EU (projects FP7‐KBBE‐2013‐7‐613549‐INDOX, FP7‐People‐2013‐ITN‐607793 and COST Action CM1303 Systems Biocatalysis) and the Spanish Government (BIO2013‐43407‐R‐DEWRY).

Summary Enzymatic biofuel cells are a class of fuel cells that utilize oxidoreductase proteins to catalyze the oxidation of fuel and/or the reduction of oxygen. Although biofuel cell cathodes typically utilize a single enzyme system, enzyme cascades are frequently necessary in biofuel cell anodes to enable deep or complete oxidation of fuels, since most oxidase and dehydrogenase enzymes only catalyze two-electron oxidation of substrates. Herein, we detail a summary of all the significant advancements made using enzyme cascades in recent years. We present examples of natural, non-natural and hybrid enzyme cascades that have been used in biofuel cells and hybrid fuel cells, and classified them either as linear, cyclic, random sequential or parallel cascades. We conclude by discussing the future directions that are necessary to the field.

peer-reviewed The electrolytes used in enzymatic biosensors or biofuel cells have always been considered to be inert. However, recent studies have demonstrated that this assumption is not correct and that the nature of the electrolyte needs to be considered. Ion specific interactions can occur with the faradaic response observed in both direct and mediated electron transfer being modulated by the nature of the salt used in solution. Specific ion effects arise from the Hofmeister series, which is well established in studies of protein systems but not in electrochemical studies of redox enzymes. Recent experimental and theoretical work on explaining the Hofmeister effect is described

Summary Currently, bioelectrocatalytic devices such as biofuel cells and bioreactors are recognized as new environment-friendly devices for the production of electricity and valuable products. Thus far, systems have been improved from the viewpoints of enzymes and electrodes. A gas diffusion bioelectrode (GDBE) is one of the best approaches to improve electrode systems. This system has been remarkably developed and essentially employed in bioelectrocatalytic systems with gaseous substrates to realize high-speed H2 oxidation and O2 reduction for biofuel cells and to realize the high-speed bioelectrocatalytic reduction of CO2. GDBEs permit the enzymes to directly use gaseous substrates, and it is imperative that the electrodes exhibit suitable porosity, conductivity, and hydrophobicity/hydrophilicity balance for the gas permeation and enzyme reaction at the bio-three-phase interface of GDBEs. In this review article, the major factors of GDBEs are discussed by highlighting recent remarkable contributions and challenges.

A novel paper‐based biofuel cell with a series/parallel array structure has been fabricated, in which the cell voltage and output power can easily be adjusted as required by printing. The output of the fabricated 4‐series/4‐parallel biofuel cell reached 0.97±0.02 mW at 1.4 V, which is the highest output power reported to date for a paper‐based biofuel cell. This work contributes to the development of flexible, wearable energy storage device.

The paper overviews various methods that are used for the analysis of output signals generated by enzyme-based logic systems. The considered methods include optical techniques (optical absorbance, fluorescence spectroscopy, surface plasmon resonance), electrochemical techniques (cyclic voltammetry, potentiometry, impedance spectroscopy, conductivity measurements, use of field effect transistor devices, pH measurements), and various mechanoelectronic methods (using atomic force microscope, quartz crystal microbalance). Although each of the methods is well known for various bioanalytical applications, their use in combination with the biomolecular logic systems is rather new and sometimes not trivial. Many of the discussed methods have been combined with the use of signal-responsive materials to transduce and amplify biomolecular signals generated by the logic operations. Interfacing of biocomputing logic systems with electronics and "smart" signal-responsive materials allows logic operations be extended to actuation functions; for example, stimulating molecular release and switchable features of bioelectronic devices, such as biofuel cells. The purpose of this review article is to emphasize the broad variability of the bioanalytical systems applied for signal transduction in biocomputing processes. All bioanalytical systems discussed in the article are exemplified with specific logic gates and multi-gate networks realized with enzyme-based biocatalytic cascades.

Todays, the greatest source of energy is supplied by fossil fuels, particularly oil. Burning of fossil fuels is associated with environmental problems, and also the resources of these fuels are limited. One of the new and effective resources of energy is biofuel cells, which is a solution for clean and renewable energy. It generates electrical energy by biological catalysts as microorganisms or enzymes. In this paper, classification, mechanism, and the favorable applications of biofuel cells are discussed. Then, the obtained results and the recommendations for further research studies in this topic are discussed.

Herein, we reported a novel ultrasensitive one-compartment enzyme biofuel cells (EBFCs)-based self-powered aptasensing platform for antibiotic residue detection. By taking full advantage of the unique features of both EBFCs-based self-powered sensors and aptamers, the as-proposed aptasensing platform has the merits of simple instrumentation, anti-interference ability, high selectivity, and low cost. In this study, DNA bioconjugate, i.e., SiO2@gold nanoparticles–complementary strand of aptamer (SiO2@AuNPs–csDNA), was elaborately designed and played a key role in blocking the mass transport of glucose to the bioanode. While in the presence of the target antibiotic, SiO2@AuNPs–csDNA bioconjugate broke away from the bioanode due to the aptamer recognition of the target. Without the blocking of glucose by the DNA bioconjugate, a significantly elevated open circuit voltage of the EBFCs-based aptasensor was obtained, whose amplitude was dependent on the antibiotic concentration. In addition, this proposed aptase...

Enzymatic biofuel cells (EBFCs) are considered as a promising approach to meet the requirements of power sources. Electrode materials, which are significant factors to affect the power output of EBFCs, have aroused great interest. Herein, we developed an EBFC using a Fe3O4–carbon nanofiber/gold nanoparticle hybrid as the substrate electrode for improving the performance of the power output. The open-circuit voltage (Eocv) of the designed EBFC reached 0.68 ± 0.03 V, and the maximum power density (Pmax) reached 126 ± 4.5 μW cm−2. The as-prepared EBFC showed 3 times higher Pmax compared to the EBFC based on the carbon nanofiber/gold nanoparticle hybrid, which was ascribed to the good electrocatalytic activity of Fe3O4 NP loaded carbon nanofibers (CNFs), the 3D porous structure of CNFs as well as the uniform distribution of Au NPs. The Fe3O4–CNF/gold nanoparticle hybrid is considered as a promising candidate for constructing electrochemical biosensors and biofuel cells.

Energy produced through enzymatic catalysis at electrodes, namely oxidation of glucose and reduction of oxygen may be used to power devices. The goal of powering implantable or semiimplantable medical devices through enzymes has driven forward the field of enzymatic bioelectrochemistry. Significant challenges must be overcome prior to their inclusion as a power source for medical devices such as low power output, poor operational stabilities and biocompatibility issues. Similar challenges hinder the development of continuous use enzymatic biosensors with poor operational stabilities and biocompatibility preventing long term deployment. This thesis aims to build on work carried out previously in the area of enzyme electrode assembly for fuel cell and biosensor development to improve the understanding and performance of glucose oxidising enzyme electrodes for enhanced operation. Novel enzyme electrode immobilisation strategies are investigated and compared with previously published enzyme electrode assemblies. Enzyme electrodes were prepared using the electropolymerisation of L-Dopa to poly(L-Dopa) as an immobilisation strategy. Improved optimisation methodologies are reported and used to assemble glucose oxidising electrodes with higher current output than those previously described.Enzyme electrodes consisting of co-immobilised redox polymer with FADGDH, MWCNTs and PEGDGE achieved current densities of 1.22 ± 0.10 mA cm-2 in PBS containing 5 mM glucose were achieved, 52 % higher than those using one factor at a time optimisation approaches. Enzyme electrodes consisting of co-immobilised redox polymer with FADGDH, MWCNTs and PEGDGE were tested in test solutions containing individual plasma components to investigate the reduced performance of enzyme electrodes in human physiological solutions. Electrodes tested in the presence of uric acid generated the lowest current responses and the lowest operational stabilities of all individual plasma components. Current densities of 0.9 ± 0.10 mA cm-2 were observed at 5 mM glucose concentrations in the presence of uric acid compared to 1.5 ± 0.10 mA cm-2 in PBS with no uric acid present. 46 % of the initial current remained after 12 hours continuous operation in the presence of uric acid compared to 72 % for PBS with no uric acid present. In comparison, glucose oxidase based electrodes maintained identical operational stabilities of 70 % with and without uric acid present while cellobiose dehydrogenase electrodes maintained 86 % stability in PBS, with 33 % stability in the presence of uric acid. Enzyme electrodes were prepared with Nafion coatings to minimise the effect of plasma on the enzymatic film. Current densities of 8.0 ± 2.0 mA cm-2 were recorded in 100 mM for glucose oxidase enzyme electrodes prepared with a 0.5 % w/v Nafion coating with an operational stability of 84 % for 12-hour continuous operation when tested in artificial plasma. FADGDH based electrodes in the same test conditions produced current densities of 4.5 ± 0.70 mA cm-2 and an operational stability of 58 %. Further work is required to fully understand changes to enzyme electrode performance in physiological solutions and strategies to minimise the impact of these solutions for operation in-vivo to allow for higher power outputs and longer operational lifetimes for prototype devices.

This review summarizes the basic features of the PQQ-GDH enzyme as one of the sugar converting biocatalysts. Focus is on the membrane -bound and the soluble form. Furthermore, the main principles of enzymatic catalysis as well as studies on the physiological importance are reviewed. A short overview is given on developments in protein engineering. The major part, however, deals with the different fields of application in bioelectrochemistry. This includes approaches for enzyme-electrode communication such as direct electron transfer, mediator-based systems, redox polymers or conducting polymers and holoenzyme reconstitution, and covers applied areas such as biosensing, biofuel cells, recycling schemes, enzyme competition, light-directed sensing, switchable detection schemes, logical operations by enzyme electrodes and immune sensing.

Flexible electroconductive hydrogel shown as a promising material for enzyme and bacterial bioelectrochemical systems. For hydrogel synthesis biocompatible polymers PEDOT PSS, carrageenan and polyvinyl alcohol were used. It is shown the mechanical properties of hydrogel and provided an electronic microscopy investigation. The oxidation processes on the electrode with enzymes and bacterial cells are demonstrated. Chosen materials and methods of synthesis did not provide any nonbiocompatible substances in hydrogels. Thus, presented materials can be promising for flexible electrodes design for biocompatible applications.

This brief presents a burst-pulse-counting supply voltage monitor for biofuel-cell-combined biosensing systems operating in a supply voltage range of 0.18–0.35 V. The proposed supply voltage monitor is designed to utilize the output of biofuel cells, which can be used to monitor biological signals, and to power circuits. A burst-pulse-counting signal conversion technique, which uses a dynamic leakage suppression (DLS) logic oscillator, a burst pulse generator, and a voltage-to-time converter, is employed to generate digital supply voltage code with fixed sampling timing and short conversion time at low power. The test chip of the proposed supply voltage monitor is implemented and fabricated in 180-nm CMOS technology, whose nominal supply voltage is 1.8 V, with an active area of 0.018 mm2. It consumes 2.1 nW at 0.3 V and achieves a conversion time range of 117–673 ms at 0.18–0.35 V with a voltage inaccuracy of +8.3/−5.5 mV.

Various carbon allotropes are fundamental components in electrochemical energy-conversion and energy-storage devices, e.g., biofuel cells (BFCs) and supercapacitors. Recently, biodevices, particularly wearable and implantable devices, are of distinct interest in biomedical, fitness, academic, and industrial fields due to their new fascinating capabilities for personalized applications. However, all biodevices require a sustainable source of energy, bringing widespread attention to energy research. In this review, we detail the progress in BFCs and supercapacitors attributed to carbon materials. Self-powered biosensors for futuristic biomedical applications are also featured. To develop these energy devices, many challenges needed to be addressed. For this reason, there is a need to: optimize the electron transfer between the enzymatic site and electrode; enhance the power efficiency of the device in fluctuating oxygen conditions; strengthen the efficacy of enzymatic reactions at the carbon-based electrodes; increase the electrochemically accessible surface area of the porous electrode materials; and refine the flexibility of traditional devices by introducing a mechanical resiliency of electrochemical devices to withstand daily multiplexed movements. This article will also feature carbon nanomaterial research alongside opportunities to enhance energy technology and address the challenges facing the field of personalized applications. Carbon-based energy devices have proved to be sustainable and compatible energy alternatives for biodevices within the human body, serving as attractive options for further developing diverse domains, including individual biomedical applications.

Miniature enzymatic biofuel cells hold great potential to power the future generation of implantable medical devices, which are currently working on external power sources used for diagnosis, prognosis and treatment. Enzymatic biofuel cells appear to be promising in harvesting the energy from biochemicals present in physiological body fluids. Glucose, which is abundantly available in the body, is being explored as a biofuel to harvest energy. The enzymes employed to harvest the energy from the biochemicals are electrically wired on gold electrodes by redox mediators. However, the limitation of insufficient power, and the sensitivity of the enzymes towards host environment restrict their in vivo application. Despite several attempts, numerous challenges remain to be addressed such as improved current density, increased stability, and biocompatibility of enzymatic biofuel cells.Foreign body reaction and isolation of the medical device by formation of a fibrous capsule may firstly denature the enzymes, and secondly hinder the diffusion of analytes and oxygen. The work described in this thesis aims at protecting glucose based biofuel cells. As a strategy for combatting the bottlenecks mentioned above, hydrogels, currently developed for various applications such as drug delivery, tissue engineering, and medical device, offer promising properties as coating materials.The first part of the thesis is focused on evaluating different low molecular weight injectable hydrogels by analysing both in vitro and in vivo gel formation, degradation kinetics, foreign body reaction and angiogenesis. The hydrogels exhibit slow degradation, and optimal tissue integration. Enhanced angiogenesis was observed due to a pro-angiogenic molecule released during hydrogel degradation.In the second part of the thesis, one of the studied hydrogels was used to coat the gold electrode functionalised with enzyme: the selection of the enzyme was based on in vitro stability studies. In parallel, the process of coating was optimised, both for uniformity and thickness. Although a thicker coating should protect the electrode against foreign body reaction, it was necessary to limit the thickness in order to maintain an efficient analyte and oxygen diffusion.Ongoing experiments described in the last part of the thesis are focused on the optimisation of implantation in rat and measurement of the biofuel cell activity. In addition, the electrodes were connected to an antenna for wireless communication; indeed, such a device would allow for a non-invasive measurement of enzyme activity.To conclude, this work allowed for the identification of a hydrogel that can be used to coat the electrodes of biofuel cells. The byproduct released during the biodegradation favours angiogenesis in the vicinity of the material. Thanks to this coating, we can therefore expect an enhanced exchange of analytes and oxygen, which is a prerequisite for enzyme activity.; Les biopiles enzymatiques miniatures représentent un potentiel important pour la future génération de dispositifs médicaux implantables, utilisés pour le diagnostic, le pronostic et le traitement. Ces derniers fonctionnent actuellement avec des sources d'énergie externes. Ces biopiles utilisant les molécules présentes dans les fluides biologiques sont des dispositifs médicaux prometteurs. Le glucose, qui est abondamment disponible dans le corps, est à l’étude comme biocarburant permettant de produire de l’énergie. Les enzymes utilisées pour produire l'énergie à partir des produits biochimiques sont immobilisées sur des électrodes en or par des médiateurs redox. Cependant, la faible puissance actuellement disponible et la sensibilité des enzymes à l'environnement limitent leur application in vivo. Malgré des recherches intensives, de nombreux problèmes restent à résoudre, notamment l'amélioration de la puissance, de la stabilité et de la biocompatibilité des biopiles.La réaction à corps étranger et l'isolement du dispositif médical par la formation d'une capsule fibreuse peuvent d'une part dénaturer les enzymes et, d'autre part, entraver la diffusion des analytes et de l'oxygène. Le travail décrit dans cette thèse vise à protéger les biopiles fonctionnant à base de glucose. Afin de résoudre les problèmes mentionnés ci-dessus, les hydrogels, actuellement développés pour diverses applications telles que l'administration de médicaments, l'ingénierie tissulaire et les dispositifs médicaux, offrent des propriétés prometteuses en tant que matériaux de revêtement.La première partie de la thèse est centrée sur l'évaluation de différents hydrogels injectables de faible poids moléculaire, en analysant à la fois la gélification in vitro et in vivo, la cinétique de dégradation, la réaction à corps étranger et l'angiogenèse. Les hydrogels présentent une dégradation lente et une intégration tissulaire optimale. Une angiogenèse accrue a été observée en raison de la libération d'une molécule pro-angiogénique pendant la dégradation de l'hydrogel.Dans la seconde partie de la thèse, l'un des hydrogels étudiés a été utilisé pour recouvrir l'électrode en or : le choix de l'enzyme a été basé sur des études de stabilité in vitro. En parallèle, le processus de revêtement a été optimisé, à la fois pour son uniformité et son épaisseur. Même si un revêtement plus épais présente l’avantage de protéger l’électrode contre la réaction à corps étranger, il est nécessaire de limiter l’épaisseur afin de maintenir une diffusion efficace des analytes et de l’oxygène.Les expériences en cours décrites dans la dernière partie de la thèse sont axées sur l'optimisation de l'implantation chez le rat et la mesure de l'activité des biopiles. De plus, les électrodes ont été connectées à une antenne pour établir une communication sans fil ; en effet, cela permettrait une mesure non invasive de l'activité enzymatique.En conclusion, ces travaux ont permis d'identifier un hydrogel pouvant être utilisé pour revêtir les électrodes de biopiles. Le sous-produit libéré lors de la biodégradation favorise l'angiogenèse au voisinage du matériau. Grâce à ce revêtement, on peut donc s'attendre à un échange accru d'analytes et d'oxygène, préalable indispensable à l'activité enzymatique.

Miniature enzymatic biofuel cells hold great potential to power the future generation of implantable medical devices, which are currently working on external power sources used for diagnosis, prognosis and treatment. Enzymatic biofuel cells appear to be promising in harvesting the energy from biochemicals present in physiological body fluids. Glucose, which is abundantly available in the body, is being explored as a biofuel to harvest energy. The enzymes employed to harvest the energy from the biochemicals are electrically wired on gold electrodes by redox mediators. However, the limitation of insufficient power, and the sensitivity of the enzymes towards host environment restrict their in vivo application. Despite several attempts, numerous challenges remain to be addressed such as improved current density, increased stability, and biocompatibility of enzymatic biofuel cells.Foreign body reaction and isolation of the medical device by formation of a fibrous capsule may firstly denature the enzymes, and secondly hinder the diffusion of analytes and oxygen. The work described in this thesis aims at protecting glucose based biofuel cells. As a strategy for combatting the bottlenecks mentioned above, hydrogels, currently developed for various applications such as drug delivery, tissue engineering, and medical device, offer promising properties as coating materials.The first part of the thesis is focused on evaluating different low molecular weight injectable hydrogels by analysing both in vitro and in vivo gel formation, degradation kinetics, foreign body reaction and angiogenesis. The hydrogels exhibit slow degradation, and optimal tissue integration. Enhanced angiogenesis was observed due to a pro-angiogenic molecule released during hydrogel degradation.In the second part of the thesis, one of the studied hydrogels was used to coat the gold electrode functionalised with enzyme: the selection of the enzyme was based on in vitro stability studies. In parallel, the process of coating was optimised, both for uniformity and thickness. Although a thicker coating should protect the electrode against foreign body reaction, it was necessary to limit the thickness in order to maintain an efficient analyte and oxygen diffusion.Ongoing experiments described in the last part of the thesis are focused on the optimisation of implantation in rat and measurement of the biofuel cell activity. In addition, the electrodes were connected to an antenna for wireless communication; indeed, such a device would allow for a non-invasive measurement of enzyme activity.To conclude, this work allowed for the identification of a hydrogel that can be used to coat the electrodes of biofuel cells. The byproduct released during the biodegradation favours angiogenesis in the vicinity of the material. Thanks to this coating, we can therefore expect an enhanced exchange of analytes and oxygen, which is a prerequisite for enzyme activity.; Les biopiles enzymatiques miniatures représentent un potentiel important pour la future génération de dispositifs médicaux implantables, utilisés pour le diagnostic, le pronostic et le traitement. Ces derniers fonctionnent actuellement avec des sources d'énergie externes. Ces biopiles utilisant les molécules présentes dans les fluides biologiques sont des dispositifs médicaux prometteurs. Le glucose, qui est abondamment disponible dans le corps, est à l’étude comme biocarburant permettant de produire de l’énergie. Les enzymes utilisées pour produire l'énergie à partir des produits biochimiques sont immobilisées sur des électrodes en or par des médiateurs redox. Cependant, la faible puissance actuellement disponible et la sensibilité des enzymes à l'environnement limitent leur application in vivo. Malgré des recherches intensives, de nombreux problèmes restent à résoudre, notamment l'amélioration de la puissance, de la stabilité et de la biocompatibilité des biopiles.La réaction à corps étranger et l'isolement du dispositif médical par la formation d'une capsule fibreuse peuvent d'une part dénaturer les enzymes et, d'autre part, entraver la diffusion des analytes et de l'oxygène. Le travail décrit dans cette thèse vise à protéger les biopiles fonctionnant à base de glucose. Afin de résoudre les problèmes mentionnés ci-dessus, les hydrogels, actuellement développés pour diverses applications telles que l'administration de médicaments, l'ingénierie tissulaire et les dispositifs médicaux, offrent des propriétés prometteuses en tant que matériaux de revêtement.La première partie de la thèse est centrée sur l'évaluation de différents hydrogels injectables de faible poids moléculaire, en analysant à la fois la gélification in vitro et in vivo, la cinétique de dégradation, la réaction à corps étranger et l'angiogenèse. Les hydrogels présentent une dégradation lente et une intégration tissulaire optimale. Une angiogenèse accrue a été observée en raison de la libération d'une molécule pro-angiogénique pendant la dégradation de l'hydrogel.Dans la seconde partie de la thèse, l'un des hydrogels étudiés a été utilisé pour recouvrir l'électrode en or : le choix de l'enzyme a été basé sur des études de stabilité in vitro. En parallèle, le processus de revêtement a été optimisé, à la fois pour son uniformité et son épaisseur. Même si un revêtement plus épais présente l’avantage de protéger l’électrode contre la réaction à corps étranger, il est nécessaire de limiter l’épaisseur afin de maintenir une diffusion efficace des analytes et de l’oxygène.Les expériences en cours décrites dans la dernière partie de la thèse sont axées sur l'optimisation de l'implantation chez le rat et la mesure de l'activité des biopiles. De plus, les électrodes ont été connectées à une antenne pour établir une communication sans fil ; en effet, cela permettrait une mesure non invasive de l'activité enzymatique.En conclusion, ces travaux ont permis d'identifier un hydrogel pouvant être utilisé pour revêtir les électrodes de biopiles. Le sous-produit libéré lors de la biodégradation favorise l'angiogenèse au voisinage du matériau. Grâce à ce revêtement, on peut donc s'attendre à un échange accru d'analytes et d'oxygène, préalable indispensable à l'activité enzymatique.

This chapter will focus on the design and synthesis of organic conducting polymers (OCPs) that are capable of effective interaction with biological systems for monitoring and/or stimulation. The choice of appropriate dopants has proven to be critical. It is known that the dopant employed influences surface roughness, surface energy, conductivity and electroactivity. All of these properties will in turn influence the ability to interact with biological systems. On adding to this the introduction of biologically active dopants or covalently attached bioactive entities, we take the control over the performance of these new biocommunication systems to a new level. Here we will focus on implantable systems based on OCPs. We will review the area of implantable biosensors for the monitoring of compounds of therapeutic relevance, as well as the firing patterns from electrically active cellular systems – nerve and muscle. The use of conducting polymer electrodes to stimulate cells to facilitate tissue regeneration is also reviewed. The use of conducting polymers as the basis of electrically controlled delivery systems is also considered. Finally, an emerging area of interest is the use of conducting polymers as the basis for implantable energy systems – biofuel cells and biobatteries.

International audience; We report the fabrication of a polymer/enzyme based biosupercapacitor (BSC)/biofuel cell (BFC) hybrid device with optimized cell voltage that can be switched on demand from energy conversion to energy storage mode. The redox polymer matrices used for the immobilization of the biocatalyst at the bioanode and biocathode act simultaneously as electron relays between the integrated redox enzymes and the electrode surface (BFC) and as pseudo-capacitive charge storing elements (BSC). Moreover, due to the self-charging effect based on the continuously proceeding enzy-matic reaction, a Nernstian-shift in the pseudo-capacitive elements, i.e. in the redox polymers, at the individual bioelectrodes leads to a maximized open circuit voltage of the device in both operating modes. Comparison with a conventional fuel cell design, i.e. using redox mediators with redox potentials that are close to the potentials of the used redox proteins, indicates that the novel hybrid device shows a similar voltage output. Moreover, our results demonstrate that the conventional design criteria commonly used for the development of redox polymers for the use in biofuel cells have to be extended by considering the effect of a Nernstian-shift towards the potentials of the used biocatalysts in those pseudo-capacitive elements.

Diffusion plays a critical role in establishing functional bio/solid soft interfaces for bioassays, biosensors, and biofuel cells. An understanding of micro-diffusion near the interface is significant for developing high-performance bioassays, biosensors, and biofuel cells. Herein, we explored micro-diffusion behavior at different temperature gaps in microfluidic chip and enzyme-linked immunosorbent assay (ELISA) microplates. It exhibited that temperature gap could distinctly promote directional diffusion of molecules in microfluidic chip from high concentration zone to low concentration zone. In addition, experimental results of specially designed ELISA also partly confirmed that the temperature gap could effectively improve the performance of ELISA by 54.5%. In compared with conventional ELISA, the as-prepared temperature-gap functional module in microfluidic chip has obvious advantages of miniaturization, integration, customization, and low cost. All in all, the current work indicates that temperature-gap function has great potential in biomedical detection, food safety, and so on. It can be utilized to develop novel biological detection approaches and related instruments or microfluidic chips.

Biofuel cell (BFC) electrodes are typically manufactured by combining enzymes that act as catalysts with conductive carbon nanomaterials in a form of enzyme-nanocomposite. However, a little attention has been paid to effects of the carbon nanomaterials' structural properties on the electrochemical performances of the enzyme-nanocomposites. This work aims at studying the effects of surface and bulk properties of carbon nanomaterials with different degrees of graphitization on the electrochemical performances of glucose oxidase (GOx)-nanocomposites produced by immobilizing GOx within a network of carbon nanopaticles. Two types of carbon nanomaterials were used: graphitized mesoporous carbon (GMC) and purified mesoporous carbon (PMC). Graphitization index, surface functional groups, hydrophobic properties, and rate of aggregation were measured for as-received and acid-treated GMC and PMC samples by using Raman spectrometry, X-ray photoelectron spectroscopy (XPS), contact angle measurement, and dynamic light scattering (DLS), respectively. In addition to these physical property characterizations, the enzyme loading and electrochemical performances of the GOx-nanocomposites were studied via elemental analysis and cyclic voltammetry tests, respectively. We also fabricated BFCs using our GOx-nanocomposite materials as the enzyme anodes, and tested their performances by obtaining current-voltage (IV) plots. Our findings suggest that the electrochemical performance of GOx-nanocomposite material is determined by the combined effects of graphitization index, electrical conductivity and surface chemistry of carbon nanomaterials.

A generic method to magnetically assemble enzymatic cascades onelectrode surfaces is introduced. The versatile method enables the simultaneous activation of both direct and mediated electron transfer bioelectrocatalysis to harness different substrates, which can serve as multiple fuels and oxidizers in biofuel cells generating clean energy., Nanoscale Advances, 1 (5), ISSN:2516-0230

Wearable sweat sensors rely either on electronics for electrochemical detection or on colorimetry for visual readout. Non-ideal form factors represent disadvantages of the former, while semiquantitative operation and narrow scope of measurable biomarkers characterize the latter. Here, we introduce a battery-free, wireless electronic sensing platform inspired by biofuel cells that integrates chronometric microfluidic platforms with embedded colorimetric assays. The resulting sensors combine advantages of electronic and microfluidic functionality in a platform that is significantly lighter, cheaper, and smaller than alternatives. A demonstration device simultaneously monitors sweat rate/loss, pH, lactate, glucose, and chloride. Systematic studies of the electronics, microfluidics, and integration schemes establish the key design considerations and performance attributes. Two-day human trials that compare concentrations of glucose and lactate in sweat and blood suggest a potential basis for noninvasive, semi-quantitative tracking of physiological status.

Microbial nanobiosensors (NBSs) contain immobilized microorganisms and a chain of transduction and are generally used for a single biochemical process. There are two classes of microbial NBSs that use the same principle for measuring the activity of metabolism in the presence of the analyte. The NBSs using immobilized microorganisms from which the products resulting from metabolism are measured are known as microbial NBSs. NBSs that measure the electrical activity of the metabolism of microorganisms when consuming a “biofuel” are generally known as bioelectrochemical cells or biofuel cells. The advantages of microbial NBSs are lower sensitivity to inhibition and contamination of the substrate; higher tolerance to pH and temperature variations; higher lifetime compared to the enzymatic ones; cheap; high variability, because they are able to adapt better to environmental conditions; cofactor independence; physiological response to toxic compounds; and ease of preparation due to the easy cultivation of microorganisms. The disadvantages of NBSs are as follows: they have a longer response time than enzymatic electrodes; and reusing them in a new measurement requires a longer time. Photomicrobial NBSs are based on the optical phenomena manifested by microorganisms in metabolic processes: photoluminescence, chemiluminescence, electroluminescence, polarization, absorbance, etc.

Extremophilic microorganisms are equipped with enzymes able to catalyze various reactions under extreme conditions of temperature, salinity, pH, hydrostatic pressure, radiation, etc. The particular characteristics of these enzymes, also known as extremozymes, represent valuable assets for advanced industrial applications. Most recently, extremophiles were used for the “green” and cost-effective production of high-quality nanomaterials on a large scale. The eco-friendly production of metallic nanoparticles and reduced graphene oxide using extremozymes, discussed here, represents an important breakthrough for various applications. Further benefits of extremozymes immobilized on a variety of nanomaterials, resulting in highly effective biohybrids including light-harvesting devices, biofuel cells, and biosensors, are also discussed. For biosensor development, the dual strategy for improving their stability and sensitivity is based on utilization of extremozymes as biocatalyst and of nanomaterials as high-loading support with role also in signal transduction. While a low assortment of such biosensors was developed so far, a largely unexploited applicative potential of combined use of extremozymes and nanomaterials in biosensing is anticipated due to their already demonstrated industrial benefits.

Das übergeordnete Prinzip des Energy Harvesting umfasst alle Ansätze, technische Geräte allein durch Nutzbarmachung der in der jeweiligen Umgebung vorhandenen Energie autark zu betreiben. Eine mögliche Technologie in diesem Zusammenhang ist die der sog. Biobrennstoffzellen, welche die chemische Energie eines vor Ort ohnehin vorhandenen natürlichen Substrats in direkt nutzbare elektrische Energie umwandeln können und nicht auf die Zufuhr externer ""Brennstoffe"" angewiesen sind. Je nach Typ des dazu verwendeten Katalysators sind verschiedene Varianten von Biobrennstoffzellen möglich, die sich in unterschiedlichen Forschungs- und Entwicklungsstadien befinden. Anwendungsmöglichkeiten werden z.B. bei der Energieversorgung medizinischer Implantate oder bei energieautarken verteilten Sensorsystemen gesehen.

WOS: 000458589000006, Enzymatic biofuel cells [EBFC], are considered to be environmentally friendly energy sources and bio-electrochemical devices. These biofuel cells are operating at ambient temperature and pH. In order to generate electricity, it is necessary to use plant and animal fluids as biofuels in this type of fuel cells. The general working principle is to produce electricity from biological materials as renewable fuels by using the recent technology. These fuel cells are bioelectronic devices that convert chemical energy into electrical energy. This transformation is mostly catalyzed by the use of oxidoreductase enzymes. However, nowadays, graphene and graphene based materials are extremely attractive materials for enzymatic biofuel cells because of their modified surface, high surface areas, electrical, mechanical and thermal properties, and also unique graphitized basal plane structure. This chapter details recent studies on the use of graphene-based composites in the area of enzymatic biofuels.

A copolymer poly(methyl methacrylate-co-vinylferrocene) was synthesized and used for the first time in a biofuel cell design. Bioanaode enzyme glucose oxidase and biocathode enzyme bilirubin oxidase were physically immobilized onto the copolymer-modified electrodes. Characterization studies were conducted by scanning electron microscopy, carbon-13, fourier transform infrared and hydrogen-1 nuclear magnetic resonance, and cyclic voltammograms. The designed biofuel cell was operated with linear sweep voltammetry. The maximum current was at 45°C with 120 µg of polymer amount. An improved power density of 323 µW cm-2 that is higher than other ferrocene-based fuel cells was obtained with 10-mM glucose at 0.4 V with the designed bioanode. © 2019 John Wiley & Sons Ltd., BEU-2013-77047330-01 112Y100, This work was supported by the Scientific & Technological Research Council of Turkey (TUBITAK) under Grant 112Y100 and the Bulent Ecevit University Research Fund under Grant BEU-2013-77047330-01.

WOS: 000458589000007, In biological systems, the conversion of chemical energy into electrical energy exhibited the importance of biological fuel cells. Thus, studies on the use of microbes and enzymes in fuel cell devices have recently increased. Reduced fossil resources and damage to the environment have led to an increase in the search for new energy sources. Electric energy can be obtained by using microbial and enzymes in fuel cells. The efficiency and durability of the material to be used in cathodic and anodic electrodes enable the efficient use of the biofuel cell. It is very important to know the properties of the membrane materials that provide ion transfer between the cathode and the anode. So, the characteristics of the materials used in these fuel cells, which can be expressed as biological fuel cells, affect the energy efficiency. This chapter is aimed to report recent developments in microbial fuel cells, enzymatic fuel cells and carbon-based fuel cells and the materials used in these fuel cells.

WOS: 000466255800013, Propanol can be present in two forms, 1-propanol and 2-propanol, and can be used as biofuel. Especially, the reduction of fossil resources required for renewable energy has paid attention for the inorganic synthesis of propanol. In this regard, the microbial production of propanol is very important. This chapter examines the latest developments in microbial production of propanol. Normally, various synthesis ways of propanol have been developed. However, it has been indicated that the optimization of fermentation conditions has enhanced the prevention of toxic propanol accumulation. For this reason, the low cost and high-efficiency propanol production with the help of biosynthetic pathways from microorganisms is one of the major challenges in microbial fuel cells.

Biofuel cells (BFCs) are energy conversion devices using biocatalysts to convert biochemical energy into electric energy. According to different catalysts, they can be divided into microbial fuel cells (MBFCs), enzyme biofuel cells (EBFCs), organelle biofuel cells (OBFCs), and photocatalytic fuel cells (PFCs). Compared with traditional fuel cells, EBFCs can provide sustainable energy under mild conditions such as physiological temperatures and near-neutral media, which have attracted extensive attention in the field of medical implants, drug pumps, biosensors and other devices. Enzyme load capacity and electron transfer rate are the key issues affecting the performance of EBFCs. Immobilization of enzyme on conductive materials with high specific surface area and good biocompatibility can effectively solve the bottleneck problems of EBFCs in actual applications such as low power density and short service life. This paper summarizes common biological enzymes of EBFCs and their immobilization methods, and emphasizes the breakthrough of nanomaterials, such as carbon nanomaterials, metal nanomaterials and composites in the fields of EBFCs. In addition, the application, challenges, and prospects of the EBFCs in the future development direction are also proposed.

In this research, we aimed to establish a guideline for designing electron mediators suitable for biofuel cells. A redox potential simulator was fabricated by combining density functional theory calculation and experiment, allowing us to select molecules with appropriate redox potentials efficiently. Previously, mediators have been developed depending on the trials and errors; thus, our strategy will speed up the development of biofuel cells with outstanding performances.

This topical review focuses on self-powered electrochemical sensor devices that use wearable biofuel cells (BFCs) that generate electricity from body fluid components, such as glucose in urine and lactate in sweat. The advantages of using BFCs as power sources for wearable health monitoring devices are discussed herein. Recently developed porous carbon materials with controlled interfaces and spaces are also explored for enhancing the output power and stability of BFCs. We describe a printed wearable high-power BFC that uses body fluids as a fuel. This topical review also explains several challenges existing in the development of self-driving health monitoring devices, such as their power output and stability.