Monoolein-Based Wireless Capacitive Sensor for Probing Skin Hydration.

Capacitive humidity sensors typically consist of interdigitated electrodes coated with a dielectric layer sensitive to varying relative humidity levels. Previous studies have investigated different polymeric materials that exhibit changes in conductivity in response to water vapor to design capacitive humidity sensors. However, lipid films like monoolein have not yet been integrated with humidity sensors, nor has the potential use of capacitive sensors for skin hydration measurements been fully explored.

Effect of Protection Polymer Coatings on the Performance of an Amperometric Galactose Biosensor in Human Plasma.

Galactose monitoring in individuals allows the prevention of harsh health conditions related to hereditary metabolic diseases like galactosemia. Current methods of galactose detection need development to obtain cheaper, more reliable, and more specific sensors. Enzyme-containing amperometric sensors based on galactose oxidase activity are a promising approach, which can be enhanced by means of their inclusion in a redox polymer coating.

Health and quality of life among women after participation in a CBPR-informed physical activity intervention: with a pandemic perspective.

The lack of culturally and contextually oriented interventions promoting physical activity (PA) has led to increased physical inactivity among women living in disadvantaged neighbourhoods in Sweden. In this study one such intervention informed by community-based participatory research (CBPR) has been evaluated among 34 women from a disadvantaged neighbourhood before and during COVID-19. Health-related quality of life (HRQOL), behavioural and biomedical outcomes were assessed directly prior and post-intervention, followed by evaluations at 6-months and 18-months follow-up during COVID-19.

Electronic Tongue for Direct Assessment of SARS-CoV-2-Free and Infected Human Saliva-A Feasibility Study.

An electronic tongue is a powerful analytical instrument based on an array of non-selective chemical sensors with a partial specificity for data gathering and advanced pattern recognition methods for data analysis. Connecting electronic tongues with electrochemical techniques for data collection has led to various applications, mostly within sensing for food quality and environmental monitoring, but also in biomedical research for the analyses of different bioanalytes in human physiological fluids. In this paper, an electronic tongue consisting of six electrodes (viz.

Continuous ex vivo glucose sensing in human physiological fluids using an enzymatic sensor in a vein replica.

Managing blood glucose can affect important clinical outcomes during the intraoperative phase of surgery. However, currently available instruments for glucose monitoring during surgery are few and not optimized for the specific application. Here we report an attempt to exploit an enzymatic sensor in a vein replica that could continuously monitor glucose level in an authentic human bloodstream.

Developing and evaluating non-invasive healthcare technologies for a group of female participants from a socioeconomically disadvantaged area.

When compared to the general population, socioeconomically disadvantaged communities frequently experience compromised health. Monitoring the divide is challenging since standardized biomedical tests are linguistically and culturally inappropriate. The aim of this study was to develop and test a unique mobile biomedical testbed based on non-invasive analysis, as well as to explore the relationships between the objective health measures and subjective health outcomes, as evaluated with the World Health Organization Quality of Life survey.

Wearable Electronic Tongue for Non-Invasive Assessment of Human Sweat.

Sweat is a promising biofluid in allowing for non-invasive sampling. Here, we investigate the use of a voltammetric electronic tongue, combining different metal electrodes, for the purpose of non-invasive sample assessment, specifically focusing on sweat. A wearable electronic tongue is presented by incorporating metal electrodes on a flexible circuit board and used to non-invasively monitor sweat on the body.

Autotolerant ceruloplasmin based biocathodes for implanted biological power sources.

High-performance autotolerant bioelectrodes should be ideally suited to design implantable bioelectronic devices. Because of its high redox potential and ability to reduce oxygen directly to water, human ceruloplasmin, HCp, the only blue multicopper oxidase present in human plasma, appears to be the ultimate biocatalyst for oxygen biosensors and also biocathodes in biological power sources. In comparison to fungal and plant blue multicopper oxidases, e.

Octaheme nitrite reductase: The mechanism of intramolecular electron transfer and kinetics of nitrite bioelectroreduction.

Detailed impedance and voltammetric studies of hexameric octaheme nitrite reductase immobilized on carbon-based nanomaterials, specifically nanotubes and nanoparticles, were performed. Well-pronounced bioelectrocatalytic reduction of nitrite on enzyme-modified electrodes was obtained. Analysis of the impedance data indicated the absence of long-lived intermediates involved in the nitrite reduction.

Non-Invasive Electrochemical Biosensors Operating in Human Physiological Fluids.

Non-invasive healthcare technologies are an important part of research and development nowadays due to the low cost and convenience offered to both healthcare receivers and providers. This work overviews the recent advances in the field of non-invasive electrochemical biosensors operating in secreted human physiological fluids, viz. tears, sweat, saliva, and urine.

Consecutive Marcus Electron and Proton Transfer in Heme Peroxidase Compound II-Catalysed Oxidation Revealed by Arrhenius Plots.

Electron and proton transfer reactions in enzymes are enigmatic and have attracted a great deal of theoretical, experimental, and practical attention. The oxidoreductases provide model systems for testing theoretical predictions, applying experimental techniques to gain insight into catalytic mechanisms, and creating industrially important bio(electro)conversion processes. Most previous and ongoing research on enzymatic electron transfer has exploited a theoretically and practically sound but limited approach that uses a series of structurally similar ("homologous") substrates, measures reaction rate constants and Gibbs free energies of reactions, and analyses trends predicted by electron transfer theory.

Hybrid dual-functioning electrodes for combined ambient energy harvesting and charge storage: Towards self-powered systems.

In the last few years, there have been an increasing number of reports where different energy harvesters are directly combined with charge storing devices, based on dual-function electrodes able to convert and store electrical energy in the same volume. This includes (bio)fuel cells harvesting chemical energy, (bio)solar cells harvesting solar energy, tribo- and piezoelectric devices harvesting mechanical energy, and thermoelectrics harvesting thermal energy, which now have been intimately combined with batteries and electrochemical capacitors. These new types of hybrid electric devices show great promise especially for the design of self-powered electronics where an integrated hybrid power system is preferable to separated ones, capable of scavenging ambient energy and simultaneously store it and in this way increasing the efficiency and enabling further miniaturization.

Challenges for successful implantation of biofuel cells.

There is a growing interest in the design and engineering of operational biofuel cells that can be implanted. This review highlights the recent progress in the electrochemistry of biofuel cell technologies, but with a particular emphasis on the medical and physiological aspects that impact the biocompatibility of biofuel cells operating inside a living body. We discuss the challenge of supplying power to implantable medical devices, with regard to the limitations of lithium battery technology and why implantable biofuel cells can be a promising alternative to provide the levels of power required for medical devices.

Evolving stability and pH-dependent activity of the high redox potential Botrytis aclada laccase for enzymatic fuel cells.

Fungal high redox potential laccases are proposed as cathodic biocatalysts in implantable enzymatic fuel cells to generate high cell voltages. Their application is limited mainly through their acidic pH optimum and chloride inhibition. This work investigates evolutionary and engineering strategies to increase the pH optimum of a chloride-tolerant, high redox potential laccase from the ascomycete Botrytis aclada.

Rechargeable, flexible and mediator-free biosupercapacitor based on transparent ITO nanoparticle modified electrodes acting in µM glucose containing buffers.

We present a transparent and flexible self-charging biosupercapacitor based on an optimised mediator- and membrane-free enzymatic glucose/oxygen biofuel cell. Indium tin oxide (ITO) nanoparticles were spray-coated on transparent conducting ITO supports resulting in a flocculent, porous and nanostructured electrode surface. By this, high capacitive currents caused by an increased electrochemical double layer as well as enhanced catalytic currents due to a higher number of immobilised enzyme molecules were obtained.

Halides inhibition of multicopper oxidases studied by FTIR spectroelectrochemistry using azide as an active infrared probe.

An infrared spectroelectrochemical study of Trametes hirsuta laccase and Magnaporthe oryzae bilirubin oxidase has been performed using azide, an inhibitor of multicopper oxidases, as an active infrared probe incorporated into the T2/T3 copper cluster of the enzymes. The redox potential-controlled measurements indicate that N stretching IR bands of azide ion bound to the T2/T3 cluster are only detected for the oxidized enzymes, confirming that azide only binds to Cu. Moreover, the process of binding/dissociation of azide ion is shown to be reversible.

Transparent, mediator- and membrane-free enzymatic fuel cell based on nanostructured chemically modified indium tin oxide electrodes.

We detail a mediator- and membrane-free enzymatic glucose/oxygen biofuel cell based on transparent and nanostructured conducting supports. Chemically modified indium tin oxide nanoparticle modified electrodes were used to substantially increase the active surface area without significantly compromising transparency. Two different procedures for surface nanostructuring were employed, viz.

An Intrinsic Self-Charging Biosupercapacitor Comprised of a High-Potential Bioanode and a Low-Potential Biocathode.

An intrinsic self-charging biosupercapacitor built on a unique concept for the fabrication of biodevices based on redox polymers is presented. The biosupercapacitor consists of a high-potential redox polymer based bioanode and a low-potential redox polymer based biocathode in which the potentials of the electrodes in the discharged state show an apparent potential mismatch E >E and prevent the use of the device as a conventional biofuel cell. Upon charging, the potentials of the electrodes are shifted to more positive (cathode) and more negative (anode) values because of a change in the a -to-a ratio within the redox polymer matrix.

Quo Vadis, Implanted Fuel Cell?

The road to safe and effective implantable electrical power devices has been long-and the goal has not been reached yet, although a certain amount of scientific and technological progress has been made. This brief review is focused on highlighting the stages of development of implanted fuel cells capable of providing electrical power for running implanted "personal electronics". The paper starts with early efforts to implant glucose-burning fuel cells in dogs, and ends with realistic attempts at interfacing a more sophisticated enzymatic glucose/oxygen fuel cell in an actual human blood stream.

Electrical activity of cellobiose dehydrogenase adsorbed on thiols: Influence of charge and hydrophobicity.

The interface between protein and material surface is of great research interest in applications varying from implants, tissue engineering to bioelectronics. Maintaining functionality of bioelements depends greatly on the immobilization process. In the present study direct electron transfer of cellobiose dehydrogenase from Humicola insolens (HiCDH), adsorbed on four different self-assembled monolayers (SAMs) formed by 5-6 chain length carbon thiols varying in terminal group structure was investigated.

A Nernstian Biosupercapacitor.

We propose the very first "Nernstian biosupercapacitor", a biodevice based on only one redox polymer: poly(vinyl imidazole-co-allylamine)[Os(bpy) Cl], and two biocatalysts. At the bioanode PQQ-dependent glucose dehydrogenase reduces the Os moieties at the polymer to Os shifting the Nernst potential of the Os /Os redox couple to negative values. Concomitantly, at the biocathode the reduction of O by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os to Os shifting the Nernst potential to higher values.

Fully Enzymatic Membraneless Glucose|Oxygen Fuel Cell That Provides 0.275 mA cm(-2) in 5 mM Glucose, Operates in Human Physiological Solutions, and Powers Transmission of Sensing Data.

Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) or [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.

Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada.

Laccases belong to the class of multicopper oxidases catalyzing the oxidation of phenols accompanied by the reduction of molecular oxygen to water without the formation of hydrogen peroxide. The activity of laccases depends on the number of Cu atoms per enzyme molecule. The structure of type 2 copper-depleted laccase from Botrytis aclada has been solved previously.

Laccase-modified gold nanorods for electrocatalytic reduction of oxygen.

cathodes. Nanostructuring was provided by gold nanorods (AuNRs), which were characterized and covalently attached to electrodes made of low-density graphite. The nanostructured electrode was the scaffold for covalent and oriented attachment of ThLc.