Bioelectrochemistry Research Papers - Academia.edu (original) (raw)

2025, ACS omega

Formation of nitro radical anion (-NO 2 •-) and other reduction products of 5-nitroimidazoles, although important for antimicrobial activity, makes the drugs neurotoxic. Hence, an appropriate generation and their role in the free radical pathway needs proper realization. This was attempted by studying the action of tinidazole and its Cu II complexes on model targets (nucleic acid bases and calf thymus DNA). Results obtained were correlated with studies on biological species where prevention of biofilm formation on Staphylococcus aureus and Pseudomonas aeruginosa was followed. Tinidazole and its Cu II complexes subjected to electrochemical reduction in aqueous solution, under de-aerated conditions, interact with model nucleic acid bases and calf thymus DNA. These model targets were followed to realize what happens when such compounds undergo enzymatic reduction within cells of microorganisms that they eventually kill. Studies reveal that Cu II complexes were better in modifying nucleic acid bases and calf thymus DNA than tinidazole; damage caused to nucleic acid bases was correlated with that caused to DNA, indicating that compounds affect DNA rich in thymine and adenine. Minimum bactericidal concentrations on sessile S. aureus and P. aeruginosa for the monomeric Cu II complex were 12.5 and 20.25 μM respectively, while those for the dimeric complex were 40.0 and 45.0 μM, respectively. Biofilm formation by P. aeruginosa and S. aureus and viability count of sessile cells were also determined. Cu II complexes of tinidazole brought about substantial reduction in carbohydrate and protein content in S. aureus and P. aeruginosa. Downregulation of quorum sensing signaling mechanism viz. reduced production of pyocyanin and elastase during biofilm formation was also detected. Cu II complexes showed much higher tendency to prevent biofilm formation than tinidazole, almost comparable to amoxicillin, an established drug in this regard.

2025, Electrochim. Acta

Direct electrochemical electron transfer (DET) of oxidoreductases has attracted increasing attention in pure and applied bioelectrochemistry (e.g. biosensors and biofuel cells) over the last decades. We report here a systematic study of DET-type bioelectrocatalysis of the membrane-bound redox enzyme fructose dehydrogenase (FDH, Gluconobacter sp.), on variable-length and variably terminated thiol self-assembled monolayers (SAMs) both on Au(111) and nanoporous gold (NPG) electrodes. FDH on Au(111) modified by short-chain moderately hydrophilic 2-mercaptoethanol (BME) SAMs exhibits the highest DET activities and largest DET-capable fraction. Fitting of theoretical polarization curves to the data and homology modeling/docking of FDH offer further mechanistic insight. The dependence of the DET efficiency of FDH on the length and differently terminated carbon chain is systematically presented. The decreased DET rate with increasing chain length is associated with increasingly unfavourable long-range electron tunnelling, and not with lowered enzyme loading. The porous structure of NPG is favorable for FDH bioelectrocatalysis by improving both efficient enzyme orientation and operational stability. Overall, our study maps systematically the controlled local environmental structural flexibility of the Au/SAM/enzyme/solution interface, a paradigm for thiol modified surfaces in biosensors and bioelectronics.

2025, Biosens. Bioelectron.

Direct electron transfer (DET) of enzymes on electrode surfaces is highly desirable both for fundamental mechanistic studies and to achieve membrane-and mediator-less bioenergy harvesting. In this report, we describe the preparation and comprehensive structural and electrochemical characterization of a threedimensional (3D) graphene-based carbon electrode, onto which the two-domain redox enzyme Myriococcum thermophilum cellobiose dehydrogenase (MtCDH) is immobilized. The electrode is prepared by an entirely novel method, which combines in a single step electrochemical reduction of graphene oxide (GO) and simultaneous electrodeposition of positively charged polyethylenimine (PEI), resulting in a well dispersed MtCDH surface. The resulting MtCDH bio-interface was characterized structurally in detail, optimized, and found to exhibit a DET maximum current density of 7.7 ± 0.9 μA cm-2 and a half-lifetime of 48 h for glucose oxidation, attributed to favorable MtCDH surface orientation. A dual, entirely DET-based enzymatic biofuel cell (EBFC) was constructed with a MtCDH bioanode and a Myrothecium verrucaria bilirubin oxidase (MvBOD) biocathode. The EBFC delivers a maximum power density (P max) of 7.6 ± 1.3 μW cm-2 , an open-circuit voltage (OCV) of 0.60 V, and an operational lifetime over seven days, which exceeds most reported CDH based DET-type EBFCs. A biosupercapacitor/EBFC hybrid was also constructed and found to register maximum power densities 62 and 43 times higher than single glucose/air and lactose/air EBFCs, respectively. This hybrid also shows excellent operational stability with self-charging/discharging over at least 500 cycles.

2025, General physiology and biophysics

In the rat erythrocyte membrane five different transport pathways for K+ are present. In addition to the well characterised K+ transport via the Na+ pump, the Na,K,Cl cotransport and the Ca(2+)-activated K+ channel, there are a K,Cl cotransport and a residual (leak) K+ transport. The K,Cl cotransport is already present under physiological conditions, and can be stimulated by N-ethylmaleimide treatment but not by a cell volume increase. A low ionic strength stimulated increase of the residual K+ influx can be demonstrated in rat erythrocytes after suppressing the K,Cl cotransport pathway. Between 11 and 19 weeks of age, rats show significant differences in all transport pathways of the erythrocyte potassium influx. Using influx data from individual rats a significant correlation between the total K+ influx and the ouabain-sensitive K+ influx has been found. Maintaining the rats on a diet poor in essential fatty acids leads to a significant change of the linoleic acid content of the e...

2025, Chem. Commun.

A quasi-solid-state and flexible biofuel cell using a hydrogel electrolyte preloaded with sugar as a fuel is described. The device can function as a self-powered biosupercapacitor delivering pulses for over 600 cycles, with a power... more

2025, ACS Applied Materials & Interfaces

A lactate/O 2 enzymatic biofuel cell (EBFC) was prepared as a potential power source for wearable microelectronic devices. Mechanically stable and flexible nanoporous gold (NPG) electrodes were prepared using an electrochemical dealloying method consisting of a pre-anodization process and a subsequent electrochemical cleaning step. Bioanodes were prepared by the electrodeposition of an Os polymer and Pediococcus sp. lactate oxidase onto the NPG electrode. The electrocatalytic response to lactate could be tuned by adjusting the deposition time. Bilirubin oxidase from Myrothecium verrucaria was covalently attached to a diazonium-modified NPG surface. A flexible EBFC was prepared by placing the electrodes between two commercially available contact lenses to avoid direct contact with the eye. When tested in air-equilibrated artificial tear solutions (3 mM lactate), a maximum power density of 1.7 ± 0.1 μW cm-2 and an open-circuit voltage of 380 ± 28 mV were obtained, values slightly lower than those obtained in phosphate buffer solution (2.4 ± 0.2 μW cm-2 and 455 ± 21 mV, respectively). The decrease was mainly attributed to interference from ascorbate. After 5.5 h of operation, the EBFC retained 20% of the initial power output.

2025, Journal of The Electrochemical Society

Nitrofurazone ͑NF͒ presents activity against Chagas' disease, yet it has a high toxicity. Its analog, hydroxymethylnitrofurazone ͑NFOH͒, is more potent against Trypanosoma cruzi and much less toxic than the parent drug, NF. The electrochemical reduction of NFOH in an aqueous medium using a glassy carbon electrode ͑GCE͒ is presented. By cyclic voltammetry in anacidic medium, one irreversible reduction peak related to hydroxylamine derivative formation was registered, being linearly pH dependent. However, from pH Ͼ 7, a reversible reduction peak at a more positive potential appears and corresponds to the formation of a nitro radical anion. The radical-anion kinetic stability was evaluated by Ip a /Ip c the current ratio of the R-NO 2 /R-NO 2 •-redox couple. The nitro radical anion decays with a second-order rate constant ͑k 2 ͒ of 6.07, 2.06, and 1.44͑ϫ10 3 ͒ L mol -1 s -1 corresponding to pH 8.29, 9.29, and 10.2, respectively, with a corresponding half-time life ͑t 1/2 ͒ of 0.33, 0.97, and 1.4 s for each pH value. By polishing the GCE surface with diamond powder and comparing with the GCE surface polished with alumina, it is shown that the presence of alumina affects the lifetime of the nitro radical anion.

2025, Journal of Environmental Chemical Engineering

In order to increase the efficiency of microbial fuel cells and related bioelectrochemical systems (BESs), one of the common approaches is to lower the resistance of the anode surface to increase the extracellular electron transfer (EET) of anode respiring bacteria (ARB). As our work demonstrates here, this approach is not ideal when dealing with common species of ARB. Bacteria colonized an electrode surface modified with graphite material doped with nonconductive calcium sulfide (CaS) more favorably than the conductive magnetite (Fe3O4) or semiconductive iron (II) sulfide (FeS). Average anodic current densities of 8.2 ± 0.25 Am -2 (Fe3O4), 10.7 ± 0.46 Am -2 (FeS) and 21.3 ± 1.12 Am -2 (CaS) were achieved as compared to that of non-doped activated carbon (5.04 ± 0.12 A m -2 ). Bioelectrochemical evaluation during growth using simple low-scan (1 mV sec -1 ) cycle voltammetry (LSCV) indicated variations in patterns which reflect the variability of the ARBs growth. On the other hand, despite the high affinity of bacteria to grow at a faster rate on Fe3O4anode and CaS-anode, as indicated by the maximum specific growth rate during the start-up exponential phase, the kinetic scan rate study of derivative cycle voltammetry (DCVs) during growth indicated accumulation of bacteria-produced mediators on iron containing anodes which reduced their electrochemical activity. Thus, irrespective of surface resistance, the CaS doped graphite represented a promising anode material which is suitable for highly efficient BES.

2025, Journal of Power Sources

h i g h l i g h t s g r a p h i c a l a b s t r a c t Conductivity in MEC is not the mean factor when dealing with common species of ARB. 3-D GAC doped with less conductive CaS outperformed the more conductive doping. GAC as 3-D MEC did... more

2025, Journal of Biosensors & Bioelectronics

Background: Recent studies suggest that elevated dopamine concentrations reduce mitochondrial membrane potential, potentially contributing to neurological or other disorders. Changes in average membrane potential of suspended cells or organelles can be monitored in real time by measuring impedance of the suspension as a labelfree assay. Methods/Results: Here we report on measurements of frequency-and time-dependent electrical impedance of mitochondrial suspensions in the presence of various substrates, including dopamine. We find that, during succinateinduced state-2 respiration, addition of either trifluoromethoxy carbonylcyanide phenylhydrazone (FCCP), a known mitochondrial uncoupler (depolarizer), or dopamine at high concentrations cause similar increases in impedance, consistent with a drop in mitochondrial membrane potential. Our results provide further evidence that dopamine reduces mitochondrial membrane potential, albeit less severely than FCCP, possibly by generating free radicals that partially perforate the mitochondrial inner membrane and/or reduce activity of respiratory complexes. These results suggest that prolonged excess dopamine can impair ATP production, with possible implications in some neurological disorders and suggesting the need for care in the use of dopamine to treat Parkinson's disease or heart failure.

2025, Bioelectrochemistry

Electrochemical studies of laccases from basidiomycetes, i.e., Trametes hirsuta, Trametes ochracea, Coriolopsis fulvocinerea, Cerrena maxima, and Cerrena unicolor, have been performed. Direct (mediatorless) electrochemistry of laccases on graphite electrodes has been investigated with cyclic voltammetry, square wave voltammetry as well as potentiometry. For all mentioned high potential laccases direct electron transfer (DET) has been registered at spectrographic graphite and highly ordered pyrolytic graphite electrodes. The characteristics of DET reactions of the enzymes were analysed under aerobic and anaerobic conditions. It is shown that the T1 site of the laccase is the primary electron acceptor, both in solution (homogenous case) and at surface of the graphite electrode (heterogeneous case). A mechanism of ET for the process of the electroreduction of oxygen at the laccase-modified graphite electrodes is proposed and the similarity of this heterogeneous process to the laccase catalysed oxygen reduction homogeneous reaction is concluded.

2025, Catalysis Communications

A novel microporous cobalt phthalocyanine network polymer (CoPc-PIM1), prepared by the Pc-forming reaction from a rigid and nonplanar bisphthalonitrile, exhibits high surface area (650 m 2 /g) with high concentration of subnanometer pores (0.6-0.7 nm). High resolution transmission electron microscopic image shows microporous structure with nanoscale voids. This material shows pronounced efficiency for desulphurisation of salt water by catalyzing the oxidation of sulphide ions with aerobic oxygen. The reaction product includes mainly elemental sulphur which poisons the catalyst. The catalyst efficiency was easily regenerated, and found to be equivalent to the fresh catalyst for several cycles.

2025, BioChip Journal

Plaque-forming microorganisms produce insoluble exopolysaccharide (EPS), which allows the microorganisms to attach strongly to the tooth surface. Then, they start forming biofilm, which is responsible for plaque formation. The green tea polyphenol epigallocatechin gallate (EGCG) is known to inhibit biofilm formation of oral bacteria. However, its inhibitory effects on biofilm formation between the teeth have not been well studied due to the lack of devices that mimic the space between the teeth. In this study, we used a microfluidic device packed with glass beads (250-300 μm in diameter) to mimic the small cavities between the teeth in order to test the inhibitory effects of EGCG on the biofilm formation of Streptococcus mutans, one of the plaque-forming microorganisms. EPS production by S. mutans was more effectively inhibited by EGCG in the microfluidic device, compared to on agar plates, suggesting that it is more effective against biofilm formation by S. mutans cells under flow conditions than under non-flow conditions, such as conditions achieved by agar plates. These results suggest that our microfluidic device may be highly useful for studying the actual effects of antimicrobial compounds against plaqueforming microorganisms.

2025, Bioelectrochemistry

A new type of ultrathin fiber microprobe for selective electroporation is reported. The microprobe is 10 cm long and has a diameter of 350 mm. This microprobe is a low cost tool, which allows electroporation of an arbitrary selected single cell or groups of cells among population with use of a standard microscope and cell culture plates. The microprobe in its basic form contains two metal microelectrodes made of a silver-copper alloy, running along the fiber, each with a diameter of 23 mm. The probe was tested in vitro on a population of normal and cancer cells. Successful targeted electroporation was observed by means of accumulation of trypan blue (TB) dye marker in the cell. The electroporation phenomenon was also verified with propidium iodide and Annexin V in fluorescent microscopy.

2025, Bioelectrochemistry

In the framework of this study, novel method for dispersion analysis of cellular suspensions is presented. The method is fundamentally based on the ability to reconstruct the exact 3D morphology of a given cell with resolution accuracy of few nanometers using AFM imaging. By applying a reverse engineering approach, the morphology of the cell is constructed based on a set of measured spatial points that describes its geometry. The permittivity spectrum of the reconstructed cell is then directly derived based on computational solution of complex potential problem using 3D Boundary Element Method. The applicability of the method is demonstrated both theoretically and experimentally with tight comparison to the well known shell models. This comparison reveals significant deviations between the models, and hence, emphasises the vast effect of morphology in dispersion analysis of cellular suspensions.

2025, Bioelectrochemistry

For a series of graphite electrodes, modified with microquantities of Pd+Pt mixture in varied proportions, surface morphology of the catalytically active phase was studied with scanning electron microscopy (SEM), while the catalytic activity was examined at electrochemical reduction of hydrogen peroxide by means of steady-state polarization curves and constant potential amperometry. It was proven that the graphite, exhibiting the highest electrocatalytic activity (modified with Pd+Pt mixed in the ratio 70%:30% at t deposit = 10 s) is distinguished with the smallest average size of the microformations. The operational characteristics of the same electrode and graphite modified with microquantities of Pd+Au mixed in the same ratio (70%:30%; t deposit = 10 s) were compared. The application of these electrodes as basic transducers in highly selective biosensors for glucose and xanthine was demonstrated.

2025, Bioelectrochemistry

In this paper we present a simple method allowing for stable laccase immobilization on various conducting surfaces that retains the activity of the enzyme. The strategy for laccase immobilization presented in this paper relies on Zr 4+ ion coordination chemistry that involves -COO - terminal groups present on the protein. Using a host of techniques, including surface plasmon resonance (SPR), quartz crystal microbalance (QCM) gravimetry, atomic force microscopy (AFM), surface enhanced Raman scattering (SERS), resonance Raman scattering (RR) and electrochemical techniques, we show that laccase bound to a surface coordinatively through zirconium phosphonate/carboxylate (ZPC) functionalities forms a stable enzymatic layer with the enzyme retaining its activity to a significant extent.

2025, Maria Perera

Building upon the recently established concept of geo-biomimetic "dark oxygen" production, this paper presents an advanced framework for BioOxyNode-X, a next-generation autonomous system designed for sustained life support and resource generation in extreme, energy-limited environments. Addressing the critical challenges of long-duration operation, we introduce a multi-modal energy harvesting strategy, integrating reverse electrodialysis (RED) films to exploit ionic gradients, thermoelectric nanoarrays for thermal differentials, and advanced piezo/triboelectric materials for kinetic energy capture. We propose a behaviorbased power modulation system featuring a sensor-priority logic tree, enabling the device to intelligently triage operations and enter "electrochemical hibernation" when energy is scarce, mimicking the adaptive resilience of extremophiles. Furthermore, we conceptualize microbial co-energy feedback loopsand a biocatalytic amplification layer, where electrogenic microbes actively contribute to and enhance the system's energy efficiency. The framework also incorporates passive wireless communication integration for networked monitoring and explores principles of emergent swarm behavior for distributed optimization. Finally, we envision biological self-cleaning and repair layers utilizing biogenic crystallizers for unprecedented longevity. These integrated innovations redefine autonomous environmental engineering, offering transformative implications for sustainable deep-sea exploration, in situ resource utilization (ISRU) on planetary bodies like Mars and icy moons, and broadening the very definition of planetary habitability.

2025, Maria Perera

Oxygen supply is a fundamental requirement for life, yet its reliable provision remains a critical challenge in remote or extreme environments, from deep-sea habitats to extraterrestrial exploration. Traditional oxygen generation methods often demand significant energy inputs and complex infrastructure. Here, we present a conceptual framework for BioOxyNode-X, a novel biomimetic platform for passive oxygen generation, directly inspired by the recently discovered phenomenon of "dark oxygen production" at the abyssal seafloor. This natural process, attributed to electrochemical activity on polymetallic nodules, suggests a pervasive, geobiologically driven oxygen source previously unaccounted for in global biogeochemical cycles. BioOxyNode-X proposes an engineered system that leverages these principles to facilitate sustained seawater electrolysis and oxygen evolution with minimal external energy input. This framework outlines the integration of active electrochemical surfaces, advanced sensor technology, and optional biohybridization strategies to create a scalable, self-regulating oxygenation infrastructure. Beyond its potential for deep-sea hypoxia mitigation, BioOxyNode-X offers transformative implications for self-sustaining life support in resource-limited, isolated systems, including Mars and Europa analogs, fundamentally reimagining humanity's interaction with extreme environments.

2025, Maria Perera

Recent discoveries of dark oxygen production from polymetallic nodules in the Clarion-Clipperton Zone (CCZ) have revealed previously unknown electrochemical processes in abyssal environments. We present evidence for a novel ecological relationship between these electrical fields and the distribution of xenophyophores, giant single-celled protists that dominate deep-sea megafauna in nodule-rich regions. Through comprehensive analysis of existing datasets from the UK-1, OMS, and APEI-6 license areas, we demonstrate that xenophyophore density exhibits a strong power-law correlation (R² = 0.973, p = 0.013) with nodule surface voltage, following the relationship: Density ∝ (Voltage)^0.315. This represents the first quantitative evidence of biological population structure governed by ambient electrical fields in marine ecosystems. Microbiome analysis reveals co-occurrence of electrogenic bacteria exclusively in xenophyophore-associated samples, suggesting potential electrochemical symbiosis. Our findings indicate that the CCZ hosts an electrobiological ecosystem where electrical gradients, rather than traditional nutrient fluxes, serve as a primary organizing force for megafaunal distribution. The scaling relationship we observe follows biological power laws, indicating evolutionary adaptation rather than random association. These results fundamentally expand our understanding of deep-sea ecology and suggest xenophyophores may function as biological indicators of subsurface electrochemical activity, with profound implications for biotechnology development and our understanding of life's adaptive capabilities.

2025

This paper has been published under Creative Common Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) allowing to download articles and share them with others as long as they credit the authors and the publisher,... more

2025

The novel biological denitrification process with electrochemical system using the bio-cathode of microbial fuel cells (MFC) presents a promising approach to reduce electron donor consumption during wastewater treatment. This method of autotrophic denitrification can utilize inorganic compounds (such as H 2 , S 2-, S 2 O 2-3 etc.) or electrodes (at a constant potential) to provide electrons for the denitrification process. This study focuses on an isolated autotrophic denitrifier strain Lyy (belonging to Stutzerimonas) and its application in bio-cathode denitrification. It was found that the extracellular electron transfer (EET) pathway between strain Lyy and electrode is facilitated via the electron shuttle phenazine-1-carboxylic acid (PCA). Especially, at a potential of-0.6 V (vs. SCE), strain Lyy can mediate inward EET from electrodes or inorganic compound into cells, enhancing denitrification with a NO-3-N removal efficiency of 98.68 ± 0.68 % within 48 h. On the other hand, effective denitrification was achieved by the bio-cathode MFC without organic carbon sources. Meanwhile, the MFC exhibited a maximum output voltage of 172 ± 6 mV and a maximum power density of 77.46 ± 6.49 mW m-2 at a load resistance of 1 kΩ, with a NO-3-N removal efficiency higher than 95 % and with no detecteable NO-2-N, which implied that bio-cathode denitrification contributes to the electricity generation. This study showed bidirectional EET phenomena and expands the potential applications for treating low-carbon, high-nitrogen wastewater using strain Lyy.

2025, Bioelectrochemistry

o-Dianisidine (3,3V-dimethoxybenzidine) is applied in the production of some dyes and also used in analytical tests. However, this compound is anticipated to be a human carcinogen. An analytical strategy utilizing square wave voltammetry for the determination of odianisidine is presented. An electrochemical system was consisted of three electrodes: carbon paste working electrode, platinum wire counter electrode and silver-silver chloride (Ag/AgCl) reference electrode. However, square wave voltammograms of direct measurements of odianisidine were found to be hardly reproducible, exhibiting few peaks due to some labile short-lived intermediates with the only exception of a quite stable peak at + 0.7 V vs. Ag/AgCl. Quantitative determination of o-dianisidine gave satisfactory results only when the carbon paste working electrode was replaced by deoxyribonucleic acids (DNA) electrode obtained by immobilization of double-stranded (ds) DNA on carbon electrode. Square wave voltammogram of DNA showed two peaks attributed to adenine and guanine and the latter was used as analytical signal. After interaction with o-dianisidine, guanine oxidation peak was reduced to the extent related to the concentration of the analyte. Initial reduction of guanine peak took place already at the concentration of o-dianisidine equal to 0.4 AM; high concentrations (above 100 AM) of the analyte quenched completely a guanine response. The presented electrochemical system enables a specific detection of o-dianisidine by the presence of an oxidation peak at + 0.7 V and its quantitative determination by measuring a reduction of guanine peak by means of a DNA sensor.

2025, Bioelectrochemistry

Electrochemical response of synthetic oligonucleotides with different DNA bases sequences was investigated to find relationships between a chain composition and a signal. All DNA mononucleotides present electroactivity at a carbon paste electrode yielding anodic peaks at potentials: 1.00 (GMP), 1.28 (AMP), 1.47 (TMP) and 1.53 V (CMP). Also 15-mer homooligonucleotides show respective anodic peaks. Electrochemical response of 15-and 19-mer oligonucleotides consisting of all four DNA bases in different amounts was determined by the composition of oligonucleotide chain. When the contribution of different bases in oligonucleotide was balanced two anodic peaks were obtained that can be attributed to guanine and adenine moieties. Thymine residue is shown as a separate peak in voltammogram when its content in oligonucleotide chain is close to 50% of the total number of bases. Cytosine also yields a peak at its significant contribution in oligonucleotide chain and both pyrimidinic moieties produce catalytic waves easier when one of them is dominating or when only one pyrimidine derivative is present in a chain. Guanine is the easiest oxidized base and it produces a peak even at its minimal contribution (one guanine residue in 19-mer oligonucleotide). Guanine peak potential is dependent on oligonucleotide concentration and oligonucleotide composition. The lowest oligonucleotide concentration detected by guanine peak was 12.5 nM whereas detected by thymine peak was 90 nM.

2025, Bioelectrochemistry

Continuous monitoring of cortisol at the surface of the skin would advance the diagnosis and treatment of cortisol-related diseases, or of elevated cortisol levels related to stress in otherwise healthy populations. Reliable and accurate detection of cortisol at the skin surface remains a limiting factor in real-time monitoring of cortisol. To address this limitation, cortisol extraction through excised human skin by reverse iontophoresis was studied in vitro in side-by-side diffusion cells using a radiolabeled probe. The skin was subjected to four direct current regimens (0, 28, 56, 113 μA cm -2 ) with the anode in the donor chamber and the cumulative cortisol concentrations recorded in the receiver chamber. The 56 and 113 μA cm -2 regimens significantly increased transport of 3 H-cortisol through the skin, and current density correlated directly with transcutaneous transport of 3 H-cortisol. The threshold of detection of electroosmotic versus passive diffusion of cortisol through the skin was between 28 and 56 μA cm -2 . The results of this study are significant in examining how lipophilic analytes found in the bloodstream respond to reverse iontophoresis across the skin. In addition, a device integration technique is presented which illustrates how continuous cortisol extraction and sensing could potentially be achieved in a conventional wearable format.

2025, Physics & astronomy international journal

Electrochemical therapy is used for cancer and its application is simple, safe, effective and induces minimal adverse effects to the body. It is not accepted as one more oncospecific therapy, among other reasons due to its lack of standardization. Therefore, the scientific problem of this research is that an electrode arrangement is not defined that maximizes tissue damage in the tumor with minimal damage to surrounding healthy tissue that allows its optimization for therapeutic planning and personalized therapy. The objective of the study is to simulate and compare the spatial distributions of the electric potential, electric field, temperature and tissue damage and pH generated by multiple pairs of electrodes that maximize the destruction of the tumor volume. It is concluded that the results suggest that multi-pair electrode configurations may be more effective for the treatment of large (diameter> 8 cm) and deep solid tumors.

2025, Journal of Electroanalytical Chemistry

Site-specific reconstituted nanoparticles were fabricated via electrochemicallycontrolled biomineralization through the immobilization of biomolecules. The work reported herein includes the immobilization of ferritin with various surface modifications, the electrochemical biomineralization of ferritins with different inorganic cores, and the electrocatalytic reduction of oxygen on the reconstituted Pt-cored ferritins. Protein immobilization on the substrate is achieved by anchoring ferritins with dithiobis-Nsuccinimidyl propionate (DTSP). A reconstitution process of site-specific electrochemical biomineralization with a protein cage loads ferritins with different core materials. The ferritin acts as a nano-scale template, a biocompatible cage, and a separator between the nanoparticles. This first demonstration of electrochemically controlled site-specific reconstitution of biomolecules provides a new tool for biomineralization and opens the way to produce the bio-templated nanoparticles by electrochemical control. The nanosized platinum-cored ferritins on gold displayed good catalytic activity for the electrochemical reduction of oxygen, which is applicable to biofuel cell applications. This results in a smaller catalyst loading on the electrodes for fuel cells or other bioelectronic devices.

2025, Microbial Cell Factories

Malachite Green (MG) dye of the triphenylmethane group is a toxic compound used in the aquaculture industry as an antifungal agent, however, it can accumulate in fish and pose toxicity. The present work aims to remove MG in Microbial Fuel Cell (MFC) as a sustainable and eco-friendly solution. Out of six samples, the highest malachite green degradation was obtained by a sample obtained from Robiki tannery site in agar plates in 24 h at 37 °C. Robiki sample was used to inoculate the anodic chamber in Microbial Fuel cell, the resulting average electricity production was 195.76 mV for two weeks. The decolorization average was almost 88%. The predominant bacteria responsible for MG decolorization and electricity production were identified using 16S rRNA as Shewanella chilikensis strain MG22 (Accession no. OP795826) and formed a heavy biofilm on the anode. At the end of the decolorization process, MG was added again for re-use of water. The results showed efficiency for re-use 3 times. To...

2025, Biofouling

This review examines the electrochemical techniques used to study extracellular electron transfer in the electrochemically active biofilms that are used in microbial fuel cells and other bioelectrochemical systems. Electrochemically active biofilms are defined as biofilms that exchange electrons with conductive surfaces: electrodes. Following the electrochemical conventions, and recognizing that electrodes can be considered reactants in these bioelectrochemical processes, biofilms that deliver electrons to the biofilm electrode are called anodic, ie electrode-reducing, biofilms, while biofilms that accept electrons from the biofilm electrode are called cathodic, ie electrode-oxidizing, biofilms. How to grow these electrochemically active biofilms in bioelectrochemical systems is discussed and also the critical choices made in the experimental setup that affect the experimental results. The reactor configurations used in bioelectrochemical systems research are also described and the authors demonstrate how to use selected voltammetric techniques to study extracellular electron transfer in bioelectrochemical systems. Finally, some critical concerns with the proposed electron transfer mechanisms in bioelectrochemical systems are addressed together with the prospects of bioelectrochemical systems as energyconverting and energy-harvesting devices.

2025, Bioelectrochemistry

A 50 Hz magnetic field effect on the growth of yeasts Saccharomyces cerevisae was studied. The cylindrical coil induced magnetic fields with inductions up to 10 mT. Duration of exposure varied up to 24 min. Exposure took place at laboratory temperature (24-26 °C) and the air ventilator maintained the temperature at the place of the sample. We measured the growth curves of yeasts in broth and we calculated the number of CFU (colony forming units) on solid soil. We found that magnetic field decreases the number of yeasts, and slowed down their growth. The result is similar to the experiments with bacteria E. coli, S. aureus and L. adecarboxylata. It seems that the magnetic fields kill a part of yeasts and the bigger part of them survives and continues in their growth.

2025, Bioelectrochemistry (Amsterdam, Netherlands)

Coenzyme Q-0 (CoQ-0) is the only Coenzyme Q lacking an isoprenoid group on the quinoid ring, a feature important for its physico-chemical properties. Here, the redox behavior of CoQ-0 in buffered and non-buffered aqueous media was examined. In buffered aqueous media CoQ-0 redox chemistry can be described by a 2-electron-2-proton redox scheme, characteristic for all benzoquinones. In non-buffered media the number of electrons involved in the electrode reaction of CoQ-0 is still 2; however, the number of protons involved varies between 0 and 2. This results in two additional voltammetric signals, attributed to 2-electrons-1H(+) and 2-electrons-0H(+) redox processes, in which mono- and di-anionic compounds of CoQ-0 are formed. In addition, CoQ-0 exhibits a complex chemistry in strong alkaline environment. The reaction of CoQ-0 and OH(-) anions generates several hydroxyl derivatives as products. Their structures were identified with HPLC/MS. The prevailing radical reaction mechanism was...

2025, Social Science Research Network

spectroscopy (XPS). According to the XPS results, TiO2 was formed in both abiotic and biotic conditions, while unstable oxide Ti2O3 was detected in the presence of Pseudomonas aeruginosa, leading to the defects in the passive film and localized corrosion. Pitting corrosion was investigated with the help of CLSM, and the largest pit depth found on Ti surface immersed in Pseudomonas aeruginosa was 1.2 μm. Ti was not immune to MIC caused by Pseudomonas aeruginosa.

2025, Metabolites

Flavonolignans occur typically in Silybum marianum (milk thistle) fruit extract, silymarin, which contains silybin, isosilybin, silychristin, silydianin, and their 2,3-dehydroderivatives, together with other minor flavonoids and a polymeric phenolic fraction. Biotransformation of individual silymarin components by human microbiota was studied ex vivo, using batch incubations inoculated by fecal slurry. Samples at selected time points were analyzed by ultrahigh-performance liquid chromatography equipped with mass spectrometry. The initial experiment using a concentration of 200 mg/L showed that flavonolignans are resistant to the metabolic action of intestinal microbiota. At the lower concentration of 10 mg/L, biotransformation of flavonolignans was much slower than that of taxifolin, which was completely degraded after 16 h. While silybin, isosilybin, and 2,3-dehydrosilybin underwent mostly demethylation, silychristin was predominantly reduced. Silydianin, 2,3-dehydrosilychristin an...

2025, Bioelectrochemistry

2025, Biochemistry & Analytical Biochemistry

A robust and effective nano-composite film based on nafion-CdTe quantum dots modified glassy carbon electrode was prepared by droplet casting. The fabricated nano-composite was used to construct a novel catalase biosensor for the determination of hydrogen peroxide. Direct electron transfer and electrocatalysis of catalase were investigated. A pair of quasi-reversible redox peaks of catalase was observed in 0.20 M deaerated phosphate buffer solution of pH 7.0. The nano-composite film showed a pronounced promotion of the direct electron transfer among catalase and glassy carbon electrode. The immobilized catalase exhibited an excellent electrocatalytic activity towards the reduction of H 2 O 2 . Cyclic Voltammetry (CV), Chronoamperometry (CA) and Electrochemical Impedance Spectroscopy (EIS) were used to characterize the performance of the prepared nanobiosensor. The results showed that the prepared biosensor could be used as an amperometric biosensor for H 2 O 2 detection. The system was also found well suited for the use of impedimetry as an excellent biosensing system for hydrogen peroxide. The electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance decreases significantly after enzymatic reaction with hydrogen peroxide concentration, so that the proposed modified electrode can be applied as an excellent nanobiosensor to the detection of ultra-traces of H 2 O 2 (2.0 × 10 -10 -2.0 × 10 -9 M).

2025

2025, Bioelectrochemistry

silicon surfaces can be controlled down to atomic level and offer a remarkable starting point for elaborating nanostructures. Hydrogenated surfaces are obtained by oxide dissolution in hydrofluoric acid or ammonium fluoride solution.... more
silicon surfaces can be controlled down to atomic level and offer a remarkable starting point for elaborating nanostructures. Hydrogenated surfaces are obtained by oxide dissolution in hydrofluoric acid or ammonium fluoride solution. Organic species are grafted onto the hydrogenated surface by a hydrosilylation reaction, providing a robust covalent Si-C bonding. Finally, probe molecules can be anchored to the organic end group, paving the way to the elaboration of sensors. Fluorescence detection is hampered by the high refractive index of silicon. However, improved sensitivity is obtained by replacing the bulk silicon substrate by a thin layer of amorphous silicon deposited on a reflector. The development of a novel hybrid SPR interface by the deposition of an amorphous silicon-carbon alloy is also presented. Such an interface allows the subsequent linking of stable organic monolayers through Si-C bonds for a plasmonic detection. On the other hand, the semiconducting properties of silicon can be used to implement field-effect label-free detection. However, the electrostatic interaction between adsorbed species may lead to a spreading of the adsorption isotherms, which should not be overlooked in practical operating conditions of the sensor. Atomically flat silicon surfaces may allow for measuring recognition interactions with local-probe microscopy.

2025, Bioelectrochemistry

This study reports on the findings from the investigation into small-scale (6.25 mL) MFCs, connected together as a network of multiple units. The MFCs contained unmodified (no catalyst) carbon fibre electrodes and for initial and later experiments, a standard ion-exchange membrane for the proton transfer from the anode to the cathode. The anode microbial culture was of the type commonly found in domestic wastewater fed with 5 mM acetate as the carbon-energy (C/E) source. The cultures were mature and acclimatised in the MFC environment for approximately 2 months before being re-inoculated in the experimental MFC units. The cathode was of the O 2 diffusion open-to-air type, but for the purposes of the polarization experiments, the cathodic electrodes were moistened with ferricyanide. The main aim of this study was to investigate the effects of connecting multiples of MFC units together as a method of scale up by using stacks and comparison of the effects of different PEM and MFC structural materials on the performance. Impedance matching (maximum-power-transfer) was achieved through calculation of total internal impedance. Three different PEM materials were compared in otherwise identical MFCs in sets of three. For individual isolated MFCs, Hyflon E87-03 was shown to produce twice, whilst E87-10 produced approximately 1.5 times the power output of the control (standard) PEM. However, when MFCs containing the E87-03 and E87-10 membranes were connected in a stack, the system suffered from severe instability and cell reversal. To study the effects of the various polymeric MFC structural materials, four small-scale units were manufactured from three different types of RP material; acrylo-butadiene-styrene coated (ABS), ABS coated (ABS-MEK) and polycarbonate (polyC). The stack of four (4) units prototyped out of polyC produced the highest power density values in polarisation experiments (80 mW/m 2 ).

2025, Advanced Energy Materials

Studies on biological photovoltaics based on intact organisms are challenging and in most cases include diffusing mediators to facilitate electrochemical communication with electrodes. However, using such mediators is impractical. Instead, surface confined Os‐polymers have been successfully used in electrochemical studies including oxidoreductases and bacterial cells but not with algae. Photoelectrogenic activity of a green alga, Paulschulzia pseudovolvox, immobilized on graphite or Os‐polymer modified graphite is demonstrated. Direct electron transfer is revealed, when no mediator is added, between algae and electrodes with electrons emerging from photolysis of water via the cells to the electrode exhibiting a photocurrent density of 0.02 μA cm−2. Os‐polymers with different redox potentials and structures are used to optimize the energy gap between the photosynthetic complexes of the cells and the Os‐polymers and those of greater solubility, better accessibility with membranes, and...

2025, Journal of Biosensors & Bioelectronics

2025, Bioelectrochemistry

Human papillomavirus (HPV) is an important etiological factor in head and neck squamous cell carcinomas (SCCs). Standard treatment of HPV-positive tumors with platinum-based radio(chemo)therapy results in a better outcome than in HPV-negative tumors. Electrochemotherapy is becoming an increasingly recognized mode of treatment in different cancers; thus, its use in the management of head and neck SCC is of considerable interest. However, response to electrochemotherapy according to HPV status of the tumors has not been evaluated yet. Thus, our aim was to compare the effect of electrochemotherapy with cisplatin or bleomycin between HPVnegative and HPV-positive human pharyngeal SCC derived cell lines and tumor models. HPV-positive cells and tumors were found to be more sensitive to electrochemotherapy with cisplatin than HPVnegative ones, whereas sensitivity to electrochemotherapy with bleomycin was similar irrespective of the HPV status. The higher sensitivity of HPV-positive cells and tumors to electrochemotherapy with cisplatin is likely due to the higher level and slower repair of DNA damage. In HPV-negative tumors, a higher number of complete responses was recorded after bleomycin-based rather than cisplatin-based electrochemotherapy, while in HPVpositive tumors electrochemotherapy with cisplatin was more effective.

2025, Bioelectrochemistry

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

2025, Bioelectrochemistry

Breast cancer cells grown on hyaluronic acid-based scaffolds as 3D in vitro model for electroporation,

2025, Bioelectrochemistry

Electroporation of cells is usually studied using cell suspensions or monolayer cultures. 3D scaffolds for cell culture have been recently designed in order to reproduce in vitro the complex and multifactorial environment experimented in vivo by cells. In fact, it is well known that 2D cell cultures are not able to simulate the complex interactions between the cells and their extracellular matrix (ECM). Recently, some examples of 3D models, like spheroids, have been investigated also in the electroporation field. Spheroids have been proposed in electrochemotherapy (ECT) studies to mimic tumor in vivo conditions: they are easy-to-handle 3D models but their sensitivity to electric field pulses depends from their diameter and, more interestingly, despite being relevant for intercellular junctions, they are not so much so for cell-ECM interactions. In this work, we propose a 3D macroscopic myxoid matrix for cell culture that would mimic the in vivo environment of myxoid stroma tumors. The myxoid stroma consists of abundant basic substances with large amounts of glycosaminoglycans (hyaluronic acid) and proteoglycans, poor collagen fibers and no elastin content. In the proposed approach, tumor cells seeded on 3D scaffolds mimic of myxoid stroma can establish both cell-cell and cell-ECM 3D interactions. The MCF7 cells (human breast adenocarcinoma cell line) were seeded in complete culture medium. Cell cultures were incubated at 37°C for either 24 h, 3 days or 7 day. Some samples were used to assess cell vitality using 3-(4,5-dimethylthiazolyl-2)-2,5-

2025

The following protocol describes how to prepare microbial fuel cells (MFCs) with Indium Tin Oxide (ITO) electrodes for use as a poised potential enrichment tool, specifically an oxic system to enrich for the cathode-oxidizing community. The protocol describes setting up four "online" MFCs that are connected to a potentiostat at a particular set voltage plus one "offline" unconnected control (to account for non-electrode related changes). One of the online MFCs is a "negative" killed substrate control (to account for abiotic medium-source current fluctuations) and the remaining three MFCs being replicate live samples. This protocol is based on advice primarily from Frauke Kracke and Annette Rowe. ATTACHMENTS Bioelectrochemistry protocol For CHI Potentiostat_v3.docx MATERIALS Equipment: Laptop computer with CHI software (Windows only, disk is in manuals drawer) CHI Potentiostat CHI1030C o Note: Potentiostat should be plugged into an emergency power outlet. When using on a on ship, use 'clean power'. When shipping and for extra peace of mind, wrap in anti-static bag. Multimeter (EXTECH True RMS Mini) Sonicator bath (JSP Ultrasonic cleaner) Autoclave Hood with UV lamp Timer Benchtop gas burner protocols.io |

2025, protocols.io

2025, Bioelectrochemistry

When implantable recording devices for brain or neural electrical activity are designed, the number of available materials for electrodes is quite limited. The material must be biocompatible with respect to ISO10993, its electrochemical properties must remain stable and the response of cells or tissues can be mitigated, especially on the glial scar. This involves electrode characterization pre-implantation and impedance spectroscopy during chronic implantation, in order to evaluate both electrode properties and performance. This study was aimed at a comparison of the long-term behavior of a nanostructured boron-doped diamond (BDD) with a nanostructured Platinum Iridium (PtIr) electrode. Firstly, a batch of cortical grids with bare and modified contacts (2mm in diameter) was engineered for implantation. Secondly a miniature swine model was developed. This study highlighted the predominant role of electrode surface roughness on the quality of recordings. Rough PtIr contacts and BDD coated ones showed comparable behavior after threemonth implantation with a slight increase of the modulus of the impedance and a tissue capsule. Nevertheless, immunohistochemistry analysis did not exhibit either a toxic or irritation reaction. With regard to biocompatibility, promising long term results are shown for both materials.

2025, Bioelectrochemistry and Bioenergetics

Former results on protein-modified electrofusion of barley protoplasts have been extended by human cell membrane electropermeation and electrofusion after preincubation of cells with proteolytic enzymes. After pulsation, the amount of cells electroporated or broken Ž . down increased eight times and also the resealing time was prolonged. That means the lipid bilayer protein content diminished by lysis has a lower resistance against permeation. However, the rule of the relative electrofusion yield determination by the protein isoelectric Ž . point is still valid. This study of biopolymer interaction with human cell membranes is a prerequisite for drug incorporation delivery and electrotransformation by nucleic acids.