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peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 23/11/2021 A compact antibiotic delivery system based on enzymatic biofuel cells was prepared, in which ampicillin was released when discharged in the presence of glucose and O2. The release of ampicillin was effective in inhibiting the growth of bacterium Escherichia coli as confirmed by ex situ and in situ release studies in culture media.

Bioelectrocatalysis has become one of the most important research fields in electrochemistry and provided a firm base for the application of important technology in various bioelectrochemical devices, such as biosensors, biofuel cells, and biosupercapacitors. The understanding and technology of bioelectrocatalysis have greatly improved with the introduction of nanostructured electrode materials and protein-engineering methods over the last few decades. Recently, the electroenzymatic production of renewable energy resources and useful organic compounds (bioelectrosynthesis) has attracted worldwide attention. In this review, we summarize recent progress in the applications of enzymatic bioelectrocatalysis.

This chapter starts by introducing several types of biofuel cells as an application of bioelectrocatalysis with the advantages and disadvantages. Challenging issues and outlook are also described. Photo-driven bioanodes and bio-solar cell are also introduced. Bioelectrochemical reactors are proposed as reverse reactions of biofuel cells. One of brilliant points of bioelectrocatalytic systems is the property that the systems can catalyze redox reactions bidirectionally and reversibly. The significance of this matter is discussed in view of hydrogen society.

Recent progress in the application of new 2D-materials—MXenes—in the design of biosensors, biofuel cells and bioelectronics is overviewed and some advances in this area are foreseen. Recent developments in the formation of a relatively new class of 2D metallically conducting MXenes opens a new avenue for the design of conducting composites with metallic conductivity and advanced sensing properties. Advantageous properties of MXenes suitable for biosensing applications are discussed. Frontiers and new insights in the area of application of MXenes in sensorics, biosensorics and in the design of some wearable electronic devices are outlined. Some disadvantages and challenges in the application of MXene based structures are critically discussed.

[EN] This article consists of a review of the main concepts and paradigms established in the field of biological fuel cells or biofuel cells. The aim is to provide an overview of the current panorama, basic concepts, and methodologies used in the field of enzymatic biofuel cells, as well as the applications of these bio-systems in flexible electronics and implantable or portable devices. Finally, the challenges needing to be addressed in the development of biofuel cells capable of supplying power to small size devices with applications in areas related to health and well-being or next-generation portable devices are analyzed. The aim of this study is to contribute to biofuel cell technology development; this is a multidisciplinary topic about which review articles related to different scientific areas, from Materials Science to technology applications, can be found. With this article, the authors intend to reach a wide readership in order to spread biofuel cell technology for different scientific profiles and boost new contributions and developments to overcome future challenges., Financial support from the Spanish Ministry of Science, Innovation and University, through the State Program for Talent and Employability Promotion 2013-2016 by means of Torres Quevedo research contract in the framework of Bio2 project (PTQ-14-07145) and from the Instituto Valenciano de Competitividad Empresarial-IVACE-GVA (BioSensCell project)

Nowadays, the sustainable treatment and exploitation of wastewater is obtaining extensive studies because of the increasing deficiency in water resources, shortage of fossil fuel, and pollution in water. So far, most conventional wastewater remedy procedures need energy and also bring about the issues of pollutants. The microbial fuel cell (MFC) is one type of microbe-catalyzed fuel cell that is able to transfer the energy in chemical form directly from an inorganic or organic materials into electricity by means of a series of bio-chemical reactions. Electricigens are the crucial factor that controls the entire microbial fuel cell performance by means of their metabolic activities and extracellular electron transport (EET). Electron export from the microbial metabolism of the electricigen itself to the anode is carried out by two major ways, that is, direct electron transport as well as mediated electron transport, dependent upon whether the electron shuttles are used in these systems. The extracellular electron transport efficiency is regulated by the voltage difference between the electron donor and the anode acceptor. Both the cell inner and outer membrane and the cell respiratory chain protein complex provide the reacting place for MFC to extract energy from microbes. These electrons are then exported to the anode either through the direct electron transport by c-cytochromes at the inner and outer membrane of the microbes as well as by conducting pili, or through the mediated electron transport induced by electron shuttles. The electron transport is considered as the main constraint condition that restrains the output performance of the microbial fuel cell. The electron shuttle induced electron transport is one of the most widely used electron transport routine for a lot of electricigens. In this work, we recombine the Escherichia coli BL21 (DE3), a strain commonly utilized to express proteins, in order to upregulate the secretion of electron shuttles so that after immobilizing it as the bio-cocatalyst beads, the current and power output of MFC could be raised by more than 9-fold. Then, we overexpress the type two NADH dehydrogenase in the inner-membrane of the electricigens to accelerate electron trans-inner-membrane motion to bridge the gap between substrate oxidation and electron transport of microbial electrocatalyst. The power density of mutant strain increases by 3.3-fold. Thirdly, we coexpress the MtrCAB electron transport protein conduits from wild-type Shewanella oneidensis MR-1 strain as well as the ribAB genes which encodes the first two step of RF biosynthesis in the E.coli BL21(DE) strain so as to improve the power density of E.coli-catalyzed MFCs by 26-fold. Doctor of Philosophy (SCBE)

Energy harvesting was and still an important point of research. Batteries have been utilized for a long time, but they are now not compatible with the downsizing of technology. Also, their need to be recharged and changed periodically is not very desirable, therefore over the years energy harvesting from the environment and the human body have been investigated. Three energy harvesting methods which are the Piezoelectric energy harvesters, the Enzymatic Biofuel cells, and Triboelectric nanogenerators (TENGs) are being discussed in the paper. Although Biofuel cells have been investigated for a long time, they are still not ready to be used in implantable biomedical devices due to their challenges and low power densities. The Piezoelectric method has been employed in many applications due to their easy fabrication techniques and the know-how of their design is familiar. TENGs are very promising energy harvesters as they can be fabricated using different materials and are considered low-cost devices

During the last few decades, the possibility of producing electrical power from the chemical energy generated by biological catalysts has instigated remarkable advances in the field of biofuel cells. Biofuel cells use glucose primarily as a fuel and are highly relevant for powering portable, wearable and implantable electronic devices. Significant merit for this advancement is attributed to redox-active polymers that act as carriers for the enzymes while they also “wire” their active site to the electrode surface. This chapter discusses in detail (the latest) trends in the chemistry, characterization and application of redox polymers in biofuel cells. First, the fundamentals of biofuel cells are outlined, along with a detailed classification of redox polymers. Finally, a thorough investigation of how redox polymers have been integrated into biofuel cell electrodes to yield power devices with promising performances is disclosed.

Enzymatic biofuel cells (EBFCs), as one of the most promising sustainable and green energy sources, have attracted significant interest. However, the limited lifetime and output power of EBFCs deriving from the intrinsic defects of natural enzyme fail to meet the requirements of commercial applications. As a robust approach, protein engineering shows promising potential to overcome these defects. In this review, we will elaborate on the basic principles, structure and electron transfer pathways of EBFCs, and discuss the strategies of protein engineering for improving the performances of EBFCs. We hope that this review will inspire researchers to envisage efficient enzymes for EBFCs and promote the commercial transformation of EBFCs in implantable medical devices, portable power batteries and even clean-power-driven cars in the near future.

Carbon microelectromechanical system (C-MEMS) and carbon nanoelectromechanical system (C-NEMS) have been identified as promising technologies for a range of biotech applications, including electrochemical biosensors, biofuel cells, neural probes, and dielectrophoretic cell trapping. Research teams around the world have devoted more and more time to this field. After almost two decades of efforts on developing C-MEMS and C-NEMS, a review of the relevant progress and addressing future research opportunities and critical issues is in order. This review first introduces C-MEMS and C-NEMS fabrication processes that fall into two categories: photolithography- and non-photolithography- based techniques. Next, a detailed discussion of the state of the art, and technical challenges and opportunities associated with C-MEMS and C-NEMS devices used in biotech applications are presented. These devices are discussed in the relevant sub-sections of biosensors, biofuel cells, intracorporeal neural probe, dielectrophoresis cell trapping, and cell culture. The review concludes with an exposition of future perspectives in C-MEMS and C-NEMS.

International audience; Enzymatic reactions involving glucose hold the potential for building implantable biosensors and embedded power generators for various medical applications. While Biofuel cells (BFCs) such as enzymatic glucose/O2 are ensured to benefit from abundant chemical resources that can be harvested in the immediate environment of the human body, the highly critical in vivo kinetics of biofuel cell is not yet fully understood. Unfortunately, existing solutions for real-time monitoring of the reaction on rodents are not possible today, or too bulky, which has a biasing impact on the animal behavior. This work presents a light, battery-less, and wireless strategy to continuously monitor a BFC implanted in a laboratory rat using a Frequency Identification (RFID) link. An extremely lightweight and flexible tag antenna of footprint lower than 10 cm² is presented with communication capability above 60 cm in field environment. The operational capabilities are demonstrated with a 24-hour continuous monitoring of an enzymatic glucose/O2 reaction, both in vitro and in vivo.

Implantable energy harvesters (IEHs) are the crucial component for self-powered devices. By harvesting energy from organisms such as heartbeat, respiration, and chemical energy from the redox reaction of glucose, IEHs are utilized as the power source of implantable medical electronics. In this review, we summarize the IEHs and self-powered implantable medical electronics (SIMEs). The typical IEHs are nanogenerators, biofuel cells, electromagnetic generators, and transcutaneous energy harvesting devices that are based on ultrasonic or optical energy. A benefit from these technologies of energy harvesting in vivo, SIMEs emerged, including cardiac pacemakers, nerve/muscle stimulators, and physiological sensors. We provide perspectives on the challenges and potential solutions associated with IEHs and SIMEs. Beyond the energy issue, we highlight the implanted devices that show the therapeutic function in vivo.

International audience; Biofuel cells (BFCs) are electrochemical devices that rely on the transformation of chemical energy into electricity through biochemical pathways, however delivering only moderate or low power and voltage. This intrinsic limitation narrows their potential applications for driving electronics and thermodynamic systems with higher energy demands than what can be delivered by the BFCs alone. Nevertheless, coupling BFCs to electronic circuits, able to raise their voltage, allows circumventing these drawbacks. In this proof-of-concept study, we demonstrate an unconventional way of achieving highly efficient electrochemical corrosion protection of an iron surface in a chloride rich medium. The required protecting cathodic potential is generated by a self-powered bioelectronic system, consisting of a BFC, which can, despite its low voltage output (0.3 V), completely prevent interfacial corrosion if it is combined with an electronic boost converter.

This chapter is focused on green aspects of the use of (bio)chemical sensors for qualitative and quantitative analysis applications. After discussing the aspects that connect chemical sensors and biosensors with the main trends of green analytical chemistry, a set of paradigmatic examples of top sustainable assays pertaining to the (bio)sensing field are selected and explored in some of their variants. These are the use of greener types of nanoparticles for chemical assays, colorimetric assays coupled with reading using a smartphone camera, the use of a portable glucose meter as a transducer for other assays different to glucose, the use of biofuel cells for estimating organic load and toxicity and finally the coupling of sensor arrays with machine learning algorithms for gas sensing (electronic noses) and liquid monitoring (electronic tongues).

The incorporation of highly active but also highly sensitive catalysts (e.g. the [FeFe] hydrogenase from Desulfovibrio desulfuricans) in biofuel cells is still one of the major challenges in sustainable energy conversion. We report the fabrication of a dual‐gas diffusion electrode H2/O2 biofuel cell equipped with a [FeFe] hydrogenase/redox polymer‐based high‐current‐density H2‐oxidation bioanode. The bioanodes show benchmark current densities of around 14 mA cm−2 and the corresponding fuel cell tests exhibit a benchmark for a hydrogenase/redox polymer‐based biofuel cell with outstanding power densities of 5.4 mW cm−2 at 0.7 V cell voltage. Furthermore, the highly sensitive [FeFe] hydrogenase is protected against oxygen damage by the redox polymer and can function under 5 % O2., A highly active but extremely O2‐sensitive [FeFe] hydrogenase that acts as a H2‐oxidation catalyst in a H2/O2 biofuel cell is integrated in a shielded bioanode and a membrane‐free H2/O2 biofuel cell. The enzyme was wired to gas diffusion electrodes by means of a viologen‐modified redox polymer matrix. Outstanding current densities of up to 14 mA cm−2 and power outputs of 5.5 mW cm−2 in a membrane‐free device were achieved.

Herein, a light-driven, membrane-less and mediator-less self-powered cytosensing platform via integration of biofuel cells (BFCs) and a photoelectrochemical strategy was developed for ultrasensitive detection of circulating tumor cells (CTCs). To construct cytosensors, an elaborately designed SH-Sgc8c aptamer/AuNP/g-C3N4 photoelectrode was used as an alternative anode for glucose oxidation, avoiding the introduction of anodic enzymes. Initially, glucose could favorably reach the photoanode surface and be easily oxidized by the photogenerated holes, while the photogenerated electrons would transfer to the biocathode and achieve biocatalytic reduction of O2, leading to a high EOCV. However, in the presence of CTCs, they could preferentially interact with the Sgc8c aptamer via specific recognition, and then complexes with large steric hindrance were immobilized on the photoanode surface, which could greatly affect the electron transfer between glucose and the photoanode surface. In this case, the EOCV decreased sharply. Encouragingly, this self-powered cytosensor exhibited an ultrasensitive response to the target CTCs in a wide concentration range from 20 to 2 × 105 cells mL−1 with a low detection limit of 10 cells mL−1 (S/N = 3), being superior to those of the reported methods. Moreover, this as-proposed self-powered cytosensor integrated with a photoelectrochemical strategy possessed unique advantages of not requiring an external power source, being anodic enzyme-free, having a simple construction process, facile miniaturization, and high selectivity and sensitivity, providing a promising and powerful tool for fundamental biochemical research and clinical diagnosis.

The first example of a fully edible biofuel cell (BFC), based solely on highly biocompatible food materials without any additional external mediators, is described. The new BFC energy-harvesting approach relies on a variety of edible plant/mushroom extract/vegetable oil/charcoal paste biocatalytic electrodes and represents an attractive route for energy harvesting towards ingestible biomedical devices. The edible BFC anode and cathode paste materials consist of biocatalytic rich mushroom, apple, plum and banana plant tissues, along with dietary activated charcoal and water-immiscible olive oil, corn oil, and sesame oil for creating the paste matrix. The ethanol/O2 BFC relies on a bioanode, based on ethanol oxidation induced by the intrinsic biocatalytic activity of its mushroom component, along with a biocathode based on oxygen-reducing apple extract containing polyphenol-oxidase and phenolic compounds. The integrated natural catalytic system and selective biocatalytic activity of the natural extracts offer successful operation of BFCs without any extra mediators or membrane separating the anode and the cathode. The mushroom/apple/olive oil-based BFC displays a favorable power density of 282 μW cm-2 with an open circuit voltage (OCV) of 0.24 V. The power and OCV signals are linearly proportional to ethanol levels and indicate promise for self-powered alcohol sensing. The food-based BFCs were reproducible and able to maintain a power performance of over 80% of their initial output for four hours. These edible energy-harvesting BFCs hold great promise for the next-generation of ingestible devices and smart self-powered biosensors for monitoring health and the digestive system.

Cells mechanical properties can show the living state of the cell since healthy cells and unhealthy cells have different mechanical properties. Atomic force microscopy (AFM) is an integral asset in such researches. In this paper, we presented the possibility to acquire mechanical properties of cells affected by 9,10-phenentrenequinone, which is very useful in biosensors and biofuel cells researches as lipophilic redox mediator. This material is also toxic to the living cells, and it becomes a challenge to detect the real effect on the cells before using it in biosensorics-related researches. AFM was utilized to assess the condition of living cells when they were influenced by 9,10-phenentrenequinone. Our results show that a very low 9 µM concentration of this material gives very little influence to cells’ mechanical properties, however cell exposure by 27 µM gives 2-times higher elastic modulus.

We discuss the perspectives of designing implantable medical devices that have the criterion of being symbiotic. Our starting point was whether the implanted device is intended to have any two-way (“duplex”) communication of energy or materials with the body. Such duplex communication extends the existing concepts of a biomaterial and biocompatibility to include the notion that it is important to consider the intended functional use of the implanted medical device. This demands a biomimetic approach to design functional symbiotic implantable medical devices that can be more efficient in mimicking what is happening at the molecular and cellular levels to create stable interfaces that allow for the unfettered exchanges of molecules between an implanted device and a body. Such a duplex level of communication is considered to be a necessary characteristic of symbiotic implanted medical devices that are designed to function for long periods of time inside the body to restore and assist the function of the body. We illustrate these perspectives with experience gained from implanting functional enzymatic biofuel cells.

In this work, nano-inspired nickel oxide nanoparticles (NiO) and polythiophene (Pth) modified bioanode was prepared for biofuel cell applications. The chemically prepared nickel oxide nanoparticles and its composite with polythiophene were characterized for elemental composition and microscopic characterization while using scanning electron microscopy. The electrochemical characterizations of polythiophene@NiO composite, biocompatible mediator ferritin (Frt) and glucose oxidase (GOx) catalyst modified glassy carbon (GC) electrode were carried out using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and charge-discharge studies. The current density of Pth@NiO/Frt/GOx bioanode was found to be 5.4 mA/cm2. The bioanode exhibited a good bio-electrocatalytic activity towards the oxidation of the glucose. The experimental studies of the bioanode are justifying its employment in biofuel cells. This will cater a platform for the generation of sustainable energy for low temperature devices.

Dramatic changes in electricity generation, use and storage are needed to keep pace with increasing demand while reducing carbon dioxide emissions. There is great potential for application of bioengineering in this area. We have the tools to re-engineer biological molecules and systems, and a significant amount of research and development is being carried out on technologies such as biophotovoltaics, biocapacitors, biofuel cells and biobatteries. However, there does not seem to be a satisfactory overarching term to describe this area, and I propose a new word—‘electrosynbionics’. This is to be defined as: the creation of engineered devices that use components derived from or inspired by biology to perform a useful electrical function. Here, the phrase ‘electrical function’ is taken to mean the generation, use and storage of electricity, where the primary charge carriers may be either electrons or ions. ‘Electrosynbionics’ is distinct from ‘bioelectronics’, which normally relates to applications in sensing, computing or electroceuticals. Electrosynbionic devices have the potential to solve challenges in electricity generation, use and storage by exploiting or mimicking some of the desirable attributes of biological systems, including high efficiency, benign operating conditions and intricate molecular structures.

In 1968 Wolfson et al. published the concept for producing energy inside the body using catalytic electrodes exposed to the body fluid as an electrolyte and utilising naturally occurring fuels such as glucose. Since then, the technology has advanced to enhance the levels of power using enzymes immobilised within three-dimensional bioelectrodes that are nanostructured. Current research in the field of enzymatic fuel cells is directed toward applying electrochemical and nanostructural expertise to increase the energy density, to increase the power density, to increase the operational stability, and to increase the voltage output. Nonetheless, biocompatibility remains the major challenge for increasing the life-time for implanted enzymatic biofuel cells. Here, we discuss the current issues for biocompatibility and suggest directions to enhance the design of biofuel cells so as to increase the life-time of implantation whilst maintaining sufficient performance to provide power for implanted medical devices.

International audience; The search for high surface area electrodes for bioelectrochemical applications is becoming more intense. In the last few years, new strategies have emerged to develop threedimensional electrode materials with very well controlled architecture providing at the same time high specific surface, bendability and flexibility. This review will highlight some of the recent work published in the last 2 years and will discuss the issue of mathematical modeling of porous electrodes and what could be the future of high surface area electrodes materials

Self-powered biosensors (SPBs) based on enzymatic biofuel cells (EFCs) and microbial fuel cells (MFCs) have attracted considerable attention due to their obvious advantages such as simple configuration and ease of miniaturization, and potential applications including clinical diagnosis, environmental monitoring, industrial process control, etc. In this review, we will summarize the recent advances in SPBs, focusing on the use of EFC-SPBs as power sources in combination with microelectronic and electrochromic devices, and the applications of MFC-based SPBs as sensors for detecting toxicity, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and assimilable organic carbon (AOC). The efforts in, for example, boosting the energy, reducing the cost, and improving the sensing performance in terms of sensitivity, accuracy and dynamic detection range are discussed. Finally, future prospects for the development of MFC-based SPBs are presented.

Electrochemistry belongs to an important branch of chemistry that deals with the chemical changes produced by electricity and the production of electricity by chemical changes. Therefore, it can not only act a powerful tool for materials synthesis, but also offer an effective platform for sensing and catalysis. As extraordinary zero-dimensional materials, carbon-based quantum dots (CQDs) have been attracting tremendous attention due to their excellent properties such as good chemical stability, environmental friendliness, nontoxicity and abundant resources. Compared with the traditional methods for the preparation of CQDs, electrochemical (EC) methods offer advantages of simple instrumentation, mild reaction conditions, low cost and mass production. In return, CQDs could provide cost-effective, environmentally friendly, biocompatible, stable and easily-functionalizable probes, modifiers and catalysts for EC sensing. However, no specific review has been presented to systematically summarize both aspects until now. In this review, the EC preparation methods of CQDs are critically discussed focusing on CQDs. We further emphasize the applications of CQDs in EC sensors, electrocatalysis, biofuel cells and EC flexible devices. This review will further the experimental and theoretical understanding of the challenges and future prospective in this field, open new directions on exploring new advanced CQDs in EC to meet the high demands in diverse applications.

The operation of wearable epidermal biofuel cells is prone to rapid irreversible deactivation effects under dynamic sweat pH changes from neutral to acidic. We demonstrate that the encapsulation of lactate-oxidase (LOx) within a hydrophobic protective carbon-paste anode imparts unusually high stability during dynamically changing pH fluctuations and allows the BFC to continue harvesting the lactate bioenergy even after long exposures to acidic conditions. The unique power-recovery ability of the carbon-paste BFC after its failure in harsh pH is attributed to the protective action of the non-polar paste environment.

Biofilms are known to be well-organized microbial communities embedded in an extracellular polymeric matrix, which supplies bacterial protection against external stressors. Biofilms are widespread and diverse, and despite the considerable large number of publications and efforts reported regarding composition, structure and cell-to-cell communication within biofilms in the last decades, the mechanisms of biofilm formation, the interaction and communication between bacteria are still not fully understood. This knowledge is required to understand why biofilms form and how we can combat them or how we can take advantage of these sessile communities, e.g. in biofuel cells. Therefore, in situ and real-time monitoring of nutrients, metabolites and quorum sensing molecules is of high importance, which may help to fill that knowledge gap. This review focuses on the potential of scanning electrochemical microscopy (SECM) as a versatile method for in situ studies providing temporal and lateral resolution in order to elucidate cell-to-cell communication, microbial metabolism and antimicrobial impact, e.g. of antimicrobial coatings through the study of electrochemical active molecules. Given the complexity and diversity of biofilms, challenges and limitations will be also discussed., publishedVersion

This chapter will review the currently available strategies for interfacing transition metal nanoparticles with enzymes and other more complex biological systems, as well as the applications of such biometal hybrids in the areas of catalysis, energy production, environmental remediation, and medicine. In the first part of this chapter, the focus will be on the many nanometal-enzyme hybrids that have been developed for applications in organic synthesis. Within the field of organic chemistry, nanometal-enzyme hybrids are often used as bifunctional catalysts to mediate different multistep transformations, as for example the dynamic kinetic resolution of alcohols and amines. The second part of this chapter will offer an overview of nanometal-enzyme hybrids that are used as bioelectrodes in biofuel cells. This area of research has grown significantly during the past decades, much because of the many potential future applications of such devices for medical purposes. Here, nanometal-enzyme hybrid based biofuel cells hold particular promise for biosensing applications, as well as for replacing battery-based solutions in actuator devices such as mechanical valves and pacemakers. In the final part of this chapter, the different strategies to use bacteria to synthesize metal nanoparticles will be reviewed. As will be shown by the many examples in this part, biologically synthesized and supported transition metal nanoparticles constitute interesting catalytic systems that could for example be used for energy production, pollutant degradation, and small molecule synthesis.

Direct electron transfer (DET)-capable oxidoreductases are enzymes that have the ability to transfer/receive electrons directly to/from solid surfaces or nanomaterials, bypassing the need for an additional electron mediator. More than 100 enzymes are known to be capable of working in DET conditions; however, to this day, DET-capable enzymes have been mainly used in designing biofuel cells and biosensors. The rapid advance in (semi) conductive nanomaterial development provided new possibilities to create enzyme-nanoparticle catalysts utilizing properties of DET-capable enzymes and demonstrating catalytic processes never observed before. Briefly, such nanocatalysts combine several cathodic and anodic catalysis performing oxidoreductases into a single nanoparticle surface. Hereby, to the best of our knowledge, we present the first review concerning such nanocatalytic systems involving DET-capable oxidoreductases. We outlook the contemporary applications of DET-capable enzymes, present a principle of operation of nanocatalysts based on DET-capable oxidoreductases, provide a review of state-of-the-art (nano) catalytic systems that have been demonstrated using DET-capable oxidoreductases, and highlight common strategies and challenges that are usually associated with those type catalytic systems. Finally, we end this paper with the concluding discussion, where we present future perspectives and possible research directions., This article belongs to the Special Issue State of the Art and Future Trends in Nanostructured Biocatalysis

Variants of the highly active [NiFeSe] hydrogenase from D. vulgaris Hildenborough that exhibit enhanced O tolerance were used as H-oxidation catalysts in H/O biofuel cells. Two [NiFeSe] variants were electrically wired by means of low-potential viologen-modified redox polymers and evaluated with respect to H-oxidation and stability against O in the immobilized state. The two variants showed maximum current densities of (450±84) μA cm −2 for G491A and (476±172) μA cm −2 for variant G941S on glassy carbon electrodes and a higher O tolerance than the wild type. In addition, the polymer protected the enzyme from O damage and high-potential inactivation, establishing a triple protection for the bioanode. The use of gas-diffusion bioanodes provided current densities for H-oxidation of up to 6.3 mA cm −2. Combination of the gas-diffusion bioanode with a bilirubin oxidase-based gas-diffusion O-reducing biocathode in a membrane-free biofuel cell under anode-limiting conditions showed unprecedented benchmark power densities of 4.4 mW cm −2 at 0.7 V and an open-circuit voltage of 1.14 V even at moderate catalyst loadings, outperforming the previously reported system obtained with the [NiFeSe] wild type and the [NiFe] hydrogenase from D. vulgaris Miyazaki F. Triple protection : A stable, high-current-density-based H-oxidation bioanode is presented. It is equipped with [NiFeSe] variants that show enhanced O tolerance, which are immobilized and wired to electrode surfaces with a low-potential viologen-modified polymer. The polymer acts simultaneously as a high-potential and O shield. The triply protected bioanodes are incorporated in membrane-free biofuel cells, which reveal benchmark performances at moderate catalyst loading.

Представлены результаты исследований по созданию электрохимических биосенсорных анализаторов и биотопливных элементов, которые проводились в Институте биохимии и физиологии микроорганизмов, Лаборатории биосенсоров, в последние пять лет. Тенденция состояла в использовании для этой цели клеток микроорганизмов; в ряде случаев эксперименты выполнены с применением ферментов. Основное внимание уделяли изучению новых свойств микробных биосенсоров (мБС) и микробных биотопливных элементов (мБТЭ), которые могли бы быть получены при использовании наноматериалов – терморасширенного графита (ТРГ), одно- и многостенных углеродных нанотрубок. Важные результаты получены при создании композиционных электродов, содержащих фермент, встроенный в многостенные полиэлектролитные капсулы. Параллельно проводились исследования свойств традиционных мБС, направленных на детекцию спиртов, углеводов, ксенобиотиков. На базе мБТЭ была создана система конвертерного накопления заряда, с помощью которой начальный потенциал топливного элемента 0,3 В поднимали до 3,2 В. Получены оценочные данные по использованию травяной лягушки Rana temporaria как источника для получения электрической энергии при окислении глюкозы собственного организма. Обсуждается возможность практического использования созданных устройств., This article is a presentation of the results obtained through scientific studies on the design of electrochemical biosensor analyzers and biofuel cells. This work has been done over the past five years at the Institute of Biochemistry and Physiology of Microorganisms, RAS in the Laboratory of biosensors. For this purpose, a particular focus was placed on the use of microbial cells; in some cases, the experiments were carried out using enzymes. The main attention was paid to the study of new properties of microbial biosensors (mBSs) and microbial biofuel cells (mBFCs), which could be constructed in combination with nanomaterials such as thermoexpanded graphite (TEG), single- and multi-wall carbon nanotubes. The main results have been obtained while fabricating composite electrolytes which contain the enzyme immobilized into multi-layer polyelectrolyte capsules. At the same time, the properties of conventional mBSs developed for detection of alcohols, carbohydrates xenobiotics were explored. A mBFE-based system for charge accumulation in the converter has been constructed. This system was used to raise the initial potential of the fuel element from 0,3 V to 3,2 V. Our estimated data showed how the grass frog Rana temporaria can be used as a source of electric energy generation after glucose oxidation in the frog body. The possibility of applying this system in practice is discussed., История науки и техники, Выпуск 6 2020

Microbial fuel cells (MFCs) are clean, renewable energy sources and they generate self-sustaining clean energy through cellular respiration. MFCs do not require any external energy to operate and do not emit any excess greenhouse gases. MFCs can also be used for bioremediation by removing toxic materials by respiring a variety of metals and other harmful elements including iron and uranium. In this article, we have discussed the principles and designs of biofuel cells.

Lacking of electron flow pathway within enzymes, enzymatic biofuel cells (EBFCs) always suffer from low power and poor stability, which limits their further application. Aiming to improve enzyme’s conductivity and stability, we constructed a conductive enzyme nanocapsule n(GOx-PPy). A self-encapsulation was triggered by adding glucose to initiate an in-situ growth of PPy network within and around the glucose oxidase (GOx). Conductive pathways, as well as protective shell, were formed between single GOx active site and PPy network, allowing enhanced electron transfer and enzymatic stability. The n(GOx-PPy)-based EBFC demonstrated 245-fold increased power output, providing a promising strategy for constructing high-performance EBFCs.

Tumors are the leading killers of human health, however, diagnosis on tumors are neither timely nor accurate due to the high detection cost and high technical requirements. For cancer diagnosis and treatment, self-powered biosensors based on enzymatic biofuel cells have the advantages of simple structure, easy miniaturization, instantaneous response to analytes, and high economic applicability. It is of great significance for the development of portable and personalized biosensors. Over the past twenty years, a number of prominent self-powered biosensors have been created to diagnose tumor via analyzing the corresponding biomarkers with low cost. What’s more, some intelligent self-powered biosensors with integrated diagnostic and therapeutic functions have also been reported. In this review, the focus of this work is on the development of self-powered biosensors in tumor diagnosis and intelligent regulation from the aspects of design and working principles. Furthermore, the challenge for the future work is also analyzed.