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

Insight into extracellular electron transfer of microorganisms is important for our understanding of electron-transport pathways in bioelectrochemical systems (e.g. biological fuel cells and microbial electrolysis cells), as well as for biogeochemical cycles, biocorrosion, and bioremediation. Two principal mechanisms for extracellular electron transfer have been proposed: 1) electroactive metabolites/secretions serve as mediators in an indirect electron-transfer process; 2) electrons transfer directly from the cells to the electrodes via either membrane cytochromes or electrically conductive pili. The latter process has been defined as direct electron transfer (DET) and has been studied intensely. It is well known that several microbes are capable of transforming a range of metal ions/minerals into nanoparticles, which remain bound to the cell membrane. However, little is understood about the role of such metallic nanoparticles in physiological electrontransfer processes, and important questions remain regarding the details of the mechanisms involved.

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- Bioelectrochemistry, Catalysis, Microbial Fuel Cells, Nanoparticles

Cyclic voltammetry (CV) was used in this work to describe the electrochemical behavior of a dual-chamber microbial fuel cell (MFC). The system performance was evaluated under vacuum and non-pressurized conditions, different reaction times, two sweep potentials, 25 and 50 mVs −1 and under different analyte solutions, such as distilled water and domestic wastewater. CV experiments were conducted by using a potentiostat with three different configurations to collect the measurements. A dual-chamber MFC system was equipped with a DupontTM Nafion ® 117 proton exchange membrane (PEM), graphite electrodes (8.0 cm × 2.5 cm × 0.2 cm) and an external electric circuit with a 100-Ω resistor. An electrolyte (0.1 M HCl, pH ≈ 1.8) was used in the cathode chamber. It was found that the proton exchange membrane plays a major role on the electrochemical behavior of the MFC when CV measurements allow observing the conductivity performance in the MFC in the absence of a reference electrode; under this potentiostat setting, less current density values are obtained on the scanned window potentials. Therefore, potentiostat setting is essential to obtain information in complex electrochemical processes present in biological systems, such as it is the case in the MFCs. Results of the study showed that wastewater constituents and the biomass suspended or attached (biofilm) over the electrode limited the electron charge transfer through the interface electrode-biofilm-liquor. This limitation can be overcome by: (i) Enhancing the conductivity of the liquor, which is a reduction of the ohmic drop, (ii) reducing the activation losses by a better catalysis, and (iii) by limiting the diffusional gradients in the bulk liquor, for instance, by forced convection. The use of the electrolyte (0.1 M HCl, pH ≈ 1.8) and its diffusion from the cathode to the anode chamber reduces the resistance to the flow of ions through the PEM and the flow of electrons through the anodic and cathodic electrolytes. Also reduces the activation losses during the electron transfer from the substrate to the electrode surface due to the electrode catalysis improvement. On the other hand, vacuum also demonstrated that it enhances the electrochemical performance of the dual-chamber MFC due to the fact that higher current densities in the system are favored.

- by Mokhtar Guizani
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- Engineering, Bioelectrochemistry, Electrochemistry, Microbial Fuel Cells

Gene electrotransfer is an established method for plasmid delivery into different tissues. Contrary to extensive in vitro studies demonstrating increased gene electrotransfer by changing the electric field direction during the pulse delivery, little is known about the efficiency of both polarities pulses in vivo. Therefore the aim of our study was to evaluate the effect of pulse polarity and orientation on the efficacy of gene electrotransfer in the murine fibrosarcoma tumor model by using the luciferase and GFP reporter gene expression plasmids. Our results demonstrated no significant difference in luciferase activity, GFP transfected area or fluorescence intensity between different sets of electric pulses. Inversion of the pulse polarity did not result in the increase of gene transfer, but non-significant enhancement up to 7-fold was detected by changing the electric field orientation in perpendicular direction. Also, transfection of surrounding skin tissue was observed, meaning t...

- by Gregor Serša
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- Bioelectrochemistry, Mice, Electroporation, Plasmids

Synchrony between mechanically separated biological systems is well known. We posed the question: can cells induce synchronous behavior in neighboring cells which are mechanically separated and which cannot communicate via chemical or electrical mechanisms. Caco-2 cell cultures were divided into three groups. "Inducer" cells were exposed to H 2 O 2 . "Detector" cells were placed in separate containers near the inducer cells but were not exposed to H 2 O 2 . Control cells were exposed to fresh media and were kept in a distant laboratory area. Samples were measured for total protein concentration, NFκB activation and structural changes, 10, 30 and 60 min after exposure respectively. Exposing inducer cells to H 2 O 2 resulted in a significant reduction in total protein content (−50%), an increase in nuclear NFκB activation (+38%), and structural damage (56%) compared to controls. There was a similar reduction in total protein content (−48%), increase in the nuclear fraction of NFκB (+ 35%) and structural damage (25%) in detector cells. These findings provide evidence in support of a non-chemical, non-electrical communication. This signaling system possibly plays a role in synchronous, stimulus-appropriate cell responses to noxious stimuli and may explain a number of cellular behaviors that are hard to explain based only on conventional cell signaling systems.

Large unilamellar magnetoliposomes (MLs) with encapsulated doxorubicin (DOX) (anticancer drug) were prepared by reverse-phase evaporation. They were exposed to an alternating magnetic field with a frequency of 3.5 MHz and an induction of 1.5 mT produced in threeturn pancake coil. The results showed that magnetoliposomes could be specifically heated to 42°C (phase transition temperature of a used lipid) in a few minutes and during this, the encapsulated doxorubicin is massively released.

- by Cestmir Altaner
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- Bioelectrochemistry, Magnetic field, Cancer Therapy, Liposomes

Previous potentiometric attempts to determine the formal potential (E 0 V) of key intracellular redox buffer glutathione resulted in contradictory values. We have developed a spectroelectrochemical method using direct reduction on metal oxide electrodes. Disulfide absorbance at 258 nm was used to titrate glutathione in the thin layer cell reversibly. At conditions close to physiological ([GSH]=0.001-0.005 mol/l, pH=7.34; I=0.1 mol/l; T=298.15 K), we have measured glutathione E 0 V=À0.22F0.02 V (NHE), corroborating the results of equilibrium measurements. Published by Elsevier B.V.

- by Vytas Reipa
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- Bioelectrochemistry, Electrochemistry, Glutathione, Spectrum analysis

Introduction: The aim of this study was to evaluate the cellular toxicity of different pH levels on the R3230AC mammary tumour cell line (clone-D) in vitro and to determine in what way the pH affects the tumour cells. The results could be used to interpret the cell damaging effects seen in electrochemical treatment of tumours (EChT), where pH alteration in tissue is the major event. Methods: Tumour cells were treated with pH 3.5, 5, 7, 9, 10 and 11 for 10, 20 or 30 min, respectively, followed by studies with the viability assay 3-(4,5-dimethylthiazol-2-yl)-2,5,-diphenyl tetrazolium bromide (methyltetrazolium (MTT)), morphological observation in phase contrast microscope (PCM) and light microscope, nucleotide analogue incorporation (BrdU; 5-Brdmo-2V -deoxyuridine), Caspase-3 activity measurement and detection of DNA fragmentation by an agarose gel electrophoresis. Results: In the viability assay, it was found that different pH levels had cytotoxic effects; these effects were dependent on the pH value and on the time of exposure at a given pH. Morphologically, cells in pH 3.5 and 5 had shrunk, were rounded and had condensed chromatin, whereas prominent cell swelling and nuclear expansion were seen in the pH 9-and 10treated cells. Gross cytolysis was found in pH 11. A BrdU incorporation assay indicated that proliferation rate is inhibited markedly both with decreasing and increasing pH. Significant Caspase-3 activity was found in pH 3.5 and 5 groups. Caspase-3 levels for the alkaline exposure were equal or below the normal control. DNA ladder formation, a characteristic of apoptosis, was only visualised in the treatment of pH 3.5 for 30 min. Conclusions: pH changes inhibit cell proliferation and decrease cell viability. The pathway of killing tumour cell in low pH probably has at least two directions: apoptosis and cell necrosis, whereas high pH results in only cell necrosis. The study suggests that low pH environment can induce apoptosis in unphysiological condition comparable with tissue pH at EChT. In addition, it seems that R3230AC mammary tumour cells are more tolerant to high pH than to acidic changes. This supports the theory that anodic EChT should be more efficient than cathodic. D

- by Henrik Von Euler
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- Bioelectrochemistry, Electrochemistry, Caspases, Cell line

We synthesized 25,26,27,28-tetrakis(11-sulfanylundecyloxy)calix[4]arene (CALIX) sensitive to dopamine and confirmed its structure by 1 H NMR and mass spectrometry. Chemisorption of CALIX molecules or their mixtures with 1-dodecanethiols (DDT) or hexadecanethiols (HDT) resulted in formation of compact low permeable monolayers as revealed by cyclic voltammetry at presence of redox probe [Fe(CN) 6 ] 3−/4− . These self-assembled monolayers (SAMs) served as sensor for dopamine. Thickness shear mode acoustic method (TSM) has been used for study the interaction of dopamine with calixarene SAM. The admittance spectra of TSM transducer have been measured and used for simultaneous determination of the changes in series resonant frequency, f S , and motional resistance, R m , respectively. Addition of dopamine resulted in substantial decrease of f S and increase of R m , which is evidence on increased viscoelastic contribution into the acoustic properties of the sensing layer. Limit of detection (LOD) for dopamine was 50 pM, which is much better in comparison with so far reported lowest LOD for dopamine-sensitive electrochemical sensors (20 nM). The sensor allowed discrimination between dopamine and epinephrine.

- by Tibor Hianik
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- Acoustics, Bioelectrochemistry, Electrochemistry, Mass Spectrometry

Various TiO 2 nanotubes on Ti50Zr alloy have been fabricated via a two step anodization method in glycol with 15 vol.% H 2 O and 0.2 M NH 4 F under anodization controlled voltages of 15, 30 and 45 V. A new sonication treatment in deionized water with three steps and total sonication time as 1 min was performed after the first anodization step in order to remove the oxide layer grown during 2 h. The second step of anodization was for 1 h and took place at the same conditions. The role of removed layer as a nano-prepatterned surface was evidenced in the formation of highly ordered nanotubular structures and morphological features were analyzed by SEM, AFM and surface wettability. The voltage-controlled anodization leads to various nanoarhitectures, with diameters in between 20 and 80 nm. As biological assay, cell culture tests with MG63 cell line originally derived from a human osteosarcoma were performed. A correlation between nanostructure morphological properties as a result of voltage-controlled anodization and cell response was established.

- by Anca Mazare
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- Bioelectrochemistry, Cell Adhesion, Scanning Electron Microscopy, Nanotechnology

The fabrication of aptamer-based electrochemical biosensors as an emerging technology has made the detection of small and macromolecular analytes easier, faster, and more suited for the ongoing transition from fundamental analytical science to the early detection of protein biomarkers. Aptamers are synthetic oligonucleotides that have undergone iterative rounds of in vitro selection for binding with high affinity to specific analytes of choice; a sensitive yet simple method to utilize aptamers as recognition entities for the development of biosensors is to transduce the signal electrochemically. In this review article, we attempt to summarize the state-of-the-art research progresses that have been published in recent years; in particular, we focus on the electrochemical biosensors that incorporate aptamers for sensing small organic molecules and proteins. Based on differences in the design of the DNA/RNA-modified electrodes, we classify aptamer-based electrochemical sensors into three categories, for which the analyte detection relies on: (a) configurational change, i.e., the analyte binding induces either an assembly or dissociation of the sensor construct; (b) conformational change, i.e., the analyte binding induces an alteration in the conformation (folding) of the surface immobilized aptamer strands; and (c) conductivity change, i.e., the analyte binding &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;switches on&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; the conductivity of the surface-bound aptamer-DNA constructs. In each section, we will discuss the performance of these novel biosensors with representative examples reported in recent literature.

- by Dipankar Sen
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- Bioelectrochemistry, Electrochemistry, Proteins, Base Sequence

African swine fever (ASF) is a very serious disease that affects members of the Suidae family. ASF first appeared in the sub-Saharan region of Africa [1], and from there the disease spread across the Transcaucasian region to Europe and Asia. There is a growing concern that the disease will spread to other areas because of travel and imports of pork products from countries where ASF is present. The causative agent of ASF is an enveloped cytoplasmic double-stranded DNA arbovirus (Asfavirus) (genome size 170–193 kbp), which is the only member of the Asfarviridae family. The natural cycle of ASF virus (ASFV) spread occurs only in some parts of Africa and in the Iberian Peninsula. The first case of an outbreak of ASF in China was reported at a suburban pig farm in Shenyang in 2018. The low concentration of viruses in environmental samples makes detection extremely difficult. Therefore, simple, accurate and fast detection methods are urgently needed. Portable detectors based on biological molecules could be very helpful for rapid diagnosis in an outbreak. The aim of this work is to verify the possibilities of direct capture of DNA on magnetic nanoparticles and subsequent detection of DNA using electrochemical methods.

- by Arli Parikesit
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- Bioinformatics, Bioelectrochemistry, Computational Biology, Electrochemistry

Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole(Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention ispaid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties ofthis polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical targetDNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinityagents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered.

- by Arunas Ramanavicius
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- Bioelectrochemistry, Nanobiotechnology, Conducting Polymers, Nanotechnology

Galvanized steel tubes are a popular mean for water distribution systems but suffer from corrosion despite their zinc or zinc alloy coatings. First, the quality of hot-dip galvanized (HDG) coatings was studied. Their microstructure, defects, and common types of corrosion were observed. It was shown that many manufactured tubes do not reach European standard (NBN EN 10240), which is the cause of several corrosion problems. The average thickness of zinc layer was found at 41 µm against 55 µm prescribed by the European standard. However, lack of quality, together with the usual corrosion types known for HDG steel tubes was not sufficient to explain the high corrosion rate (reaching 20 µm per year versus 10 µm/y for common corrosion types). Electrochemical tests were also performed to understand the corrosion behaviours occurring in galvanized steel tubes. Results have shown that the limiting step was oxygen diffusion, favouring the growth of anaerobic bacteria in steel tubes. EDS analysis was carried out on corroded coatings and has shown the presence of sulphur inside deposits, suggesting the likely bacterial activity. Therefore biocorrosion effects have been investigated. Actually sulphate reducing bacteria (SRB) can reduce sulphate contained in water to hydrogen sulphide (H2S), causing the formation of metal sulphides. Although microbial corrosion is well-known in sea water, it is less investigated in supply water. Thus, an experimental water main was kept in operation for 6 months. SRB were detected by BART tests in the test water main.

- by F. Delaunois
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- Bioelectrochemistry, Biofilms, Corrosion, Water Supply

Microbial fuel cells (MFCs) are recognized as a future technology with a unique ability to exploit metabolic activities of living microorganisms for simultaneous conversion of chemical energy into electrical energy. This technology holds the promise to offer sustained innovations and continuous development towards many different applications and value-added production that extends beyond electricity generation, such as water desalination, wastewater treatment, heavy metal removal, bio-hydrogen production, volatile fatty acid production and biosensors. Despite these advantages, MFCs still face technical challenges in terms of low power and current density, limiting their use to powering only small-scale devices. Description of some of these challenges and their proposed solutions is demanded if MFCs are applied on a large or commercial scale. On the other hand, the slow oxygen reduction process (ORR) in the cathodic compartment is a major roadblock in the commercialization of fuel cells for energy conversion. Thus, the scope of this review article addresses the main technical challenges of MFC operation and provides different practical approaches based on different attempts reported over the years.

- by Ola Gomaa and +2
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- Bioelectrochemistry, Biofilms, Synthesis of nanoparticles, Biotechnology

The electrochemical impedance spectroscopy (EIS) technique has been shown to be an effective tool for monitoring endothelial cell behaviour on a multilayer functionalised gold electrode. Polystyrene, a reproducible model substrate, is deposited as a thin layer on a thiol functionalised gold electrode. Fibronectin, a protein promoting endothelial cell adhesion, is then adsorbed on the polystyrene surface. The different steps of this multilayer assembly are characterized by Faradaic impedance. The charge transfer resistance and the capacitance for the total layer are modified at each step according to the electrical properties of each layer. This gives the endothelial cells' electrical state in terms of its resistive and capacitive properties. In this study, the endothelial cell layer presents a specific charge transfer resistance equal to 1.55 kΩ cm 2 with no large defects in the cell layer, and a specific capacitance equal to few μF cm − 2 explained by the existence of pseudopods. These electrical properties are correlated to the endothelial cell viability, adhesion and cytoskeleton organization.

- by Ali Othmane
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- Bioelectrochemistry, Electrochemistry, Cell Adhesion, Cell line

Performance of microbial fuel cells (MFCs), fabricated using an earthen pot (MFC-1) and a proton exchange membrane (MFC-2), was evaluated while treating rice mill wastewater at feed pH of 8.0, 7.0 and 6.0. A third MFC (MFC-3), fabricated using a proton exchange membrane (PEM), was operated as control without pH adjustment of the acidic raw wastewater. Maximum chemical oxygen demand (COD) removal efficiencies of 96.5% and 92.6% were obtained in MFC-1 and MFC-2, respectively, at feed pH of 8.0. MFC-3 showed maximum COD removal of 87%. The lignin removal was 84%, 79%, and 77% and the phenol removal was 81%, 77%, and 76% in MFC-1, MFC-2, and MFC-3, respectively. Maximum sustainable volumetric power was obtained at feed pH of 8.0, and it was 2.3 W/m 3 and 0.53 W/m 3 , with 100 Ω external resistance, in MFC-1 and MFC-2, respectively. The power was lower at lower feed pH. MFC-3 generated lowest volumetric power (0.27 W/m 3 ) as compared to MFC-1 and MFC-2. More effective treatment of rice mill wastewater and higher energy recovery was demonstrated by earthen pot MFC as compared to MFC incorporated with PEM.

- by Tanaji More
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- Bioelectrochemistry, Electrochemistry, Proton Exchange Membrane, Wastewater Treatment

Transforming organic waste directly into electricity or indirectly into sources of hydrogen fuel is credible through exoelectrogen microorganisms grown on the anode or cathode that catalyze electrochemical reactions. In this review, we discuss the origin of the electrochemical kinetic in both microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) that are utilized to produce energy from waste through either directly by producing electric energy, or indirectly through hydrogen gas production, respectively. The concept of utilizing electrochemical techniques of cyclic voltammetry, chronoamperometric and derivative cyclic voltammetry to study the interfacial kinetics of exoelectro-genic bacteria and characterize biofilms are described. Additionally, we discuss the influence of various parts of electrochemical cells on bioelectrocatalytic processes, i.e, system design, electrolyte properties, anode and cathode materials. Thus, the necessity of optimizing parameters impacting the efficiency, rate, bacteria enrichment, and system implementations for improved biofilm performance are briefly discussed along with the figures of merit.

Melatonin secretion by the pineal gland has been reported to be affected by exposure to electromagnetic fields (EMFs). In an initial investigation to determine if calcifications commonly found in the pineal gland could respond to EMFs by a transducer mechanism, studies were conducted to ascertain if pineal tissues were piezoelectric. Second harmonic generation (SHG) measurements showed that pineal tissues contained noncentrosymmetric crystals, thus proving the presence of piezoelectricity. Both mulberry-like and faceted crystalline calcifications were observed by scanning electron microscopy (SEM). Some of the calcifications had compositions similar to that of hydroxyapatite; others contained a high concentration of aluminum.

- by alexandra hellen
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- Bioelectrochemistry

Recent advances in nanobiotechnology involve the use of biomolecule-nanoparticle (NP) hybrid systems for bioelectronic applications. This is exemplified by the electrical contacting of redox enzymes by means of Au-NPs. The enzymes, glucose oxidase, GOx, and glucose dehydrogenase, GDH, are electrically contacted with the electrodes by the reconstitution of the corresponding apo-proteins on flavin adenine dinucleotide (FAD) or pyrroloquinoline quinone (PQQ)-functionalized Au-NPs (1.4 nm) associated with electrodes, respectively. Similarly, Au-NPs integrated into polyaniline in a micro-rod configuration associated with electrodes provides a high surface area matrix with superior charge transport properties for the effective electrical contacting of GOx with the electrode. A different application of biomolecule-Au-NP hybrids for bioelectronics involves the use of Au-NPs as carriers for a nucleic acid that is composed of hemin/G-quadruplex DNAzyme units and a detecting segment complementary to the analyte DNA. The functionalized Au-NPs are employed for the amplified DNA detection, and for the analysis of telomerase activity in cancer cells, using chemiluminescence as a readout signal.

- by Itamar Willner
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- Bioelectrochemistry, Electronics, Photochemistry, Biotechnology

Nanoporous gold (NPG) obtained via dealloying of Au alloys has potential applications in a range of fields, and in particular in bioelectrochemistry. NPG possesses a three dimensional bicontinuous network of interconnected pores with typical pore diameters of ca. 30-40 nm, features that are useful for the immobilisation of enzymes. This review describes the common routes of fabrication and characterization of NPG, the use of NPG as a support for oxidoreductases for applications in biosensors and biofuel cells together with recent progress in the use of NPG electrodes for applications in bioelectrochemistry.

- by xx xiao and +2
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- Bioelectrochemistry, Biofuel cells, Glucose Sensors, Nanoporous Gold

The major insecurities facing the modern world are tied to depleting fuel reserves and rising greenhouse gas emissions. A quest for clean and renewable fuels has invigorated research efforts in both developed and developing countries. Microbial Fuel Cell (MFC) technology has been promoted as an innovative application of microbes for producing sustainable energy from organic waste streams emerging from a variety of waste sources. The latest scientific discoveries in MFC technology provide a framework for multitude of MXC technologies, ranging from Microbial Desalination Cells (MDCs) used in desalination of brackish water; Microbial Electrolysis Cells (MECs) used for production of hydrogen; and microbial solar cells (MSCs) for sequestration of carbon dioxide from atmospheric and anthropogenic sources. The MXCs demonstrate a potential for sustainable water treatment and clean energy production under environmentally benign conditions. This article provides a critical overview of MXCs with a special focus on MDCs. Figure 1: A schematic of microbial desalination cell [11].

Ž w Molt-4 T-lymphoblastoid cells have been exposed to pulsed signals at cellular telephone frequencies of 813.5625 MHz iDEN . Ž . Ž y1 w signal and 836.55 MHz TDMA signal . These studies were performed at low SAR averages 2.4 and 24 mW g for iDEN and 2.6 y1 . and 26 mW g for TDMA in studies designed to look for athermal RF effects. The alkaline comet, or single cell gel electrophoresis, Ž . assay was employed to measure DNA single-strand breaks in cell cultures exposed to the radiofrequency RF signal as compared to concurrent sham-exposed cultures. Tail moment and comet extent were calculated as indicators of DNA damage. Statistical differences in the distribution of values for tail moment and comet extent between exposed and control cell cultures were evaluated with the Kolmogorov-Smirnoff distribution test. Data points for all experiments of each exposure condition were pooled and analyzed as single .

- by Mary Campbell-Beachler and +1
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- Bioelectrochemistry, DNA damage, Cell Culture, Comet Assay

Electrical charging of lipid membranes causes electroporation with sharp membrane conductance increases. Several recent observations, especially at very high field strength, are not compatible with the simple electroporation picture. Here we present several relevant experiments on cell electrical responses to very high external voltages. We hypothesize that, not only are aqueous pores created within the lipid membranes, but that nanoscale membrane fragmentation occurs, possibly with micelle formation. This effect would produce conductivity increases beyond simple electroporation and display a relatively fast turn-off with external voltage. In addition, material loss can be expected at the anode side of cells, in agreement with published experimental reports at high fields. Our hypothesis is qualitatively supported by molecular dynamics simulations. Finally, such cellular responses might temporarily inactivate voltage-gated and ion-pump activity, while not necessarily causing cell death. This hypothesis also supports observations on electrofusion.

Enzymatic decolorization of reactive blue 221 (RB221) using laccase was investigated in a dual-chamber microbial fuel cell (MFC). Suspended laccase was used in the cathode chamber in the absence of any mediators in order to decolorize RB221 and also improve oxygen reduction reaction in the cathode. Molasses was utilized as low cost and high strength energy source in the anode chamber. The capability of MFC for simultaneous molasses and dye removal was investigated. A decolorization efficiency of 87% was achieved in the cathode chamber and 84% COD removal for molasses was observed in the anode chamber. Laccase could catalyze the removal of RB221 and had positive effect on MFC performance as well. Maximum power density increased about 30% when enzymatic decolorization was performed in the cathode chamber.

- by Hamid Kariminia
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- Bioelectrochemistry, Multidisciplinary, Electricity, Color
- by Arzum Erdem and +1
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- Bioelectrochemistry

In order to incorporate integral proteins in a functionally active state, metal-supported lipid bilayers must have a hydrophilic region interposed between the bilayer and the metal. This region is realized with a hydrophilic molecule terminating at one end with a sulfhydryl or disulfide group that anchors this ''hydrophilic spacer'' to the surface of a metal, such as gold or mercury. The other end of the hydrophilic spacer may be covalently linked to the polar head of a phospholipid molecule, giving rise to a supramolecule called ''thiolipid'' (TL). With respect to gold, mercury has the advantage of providing a defect-free and fluid surface to the self-assembling spacer. Hydrophilic spacers consisting of a polyethyleneoxy or a hexapeptide chain, as well as thiolipids derived from these spacers, were employed to fabricate mercurysupported lipid bilayers. The formation of a lipid bilayer on top of a self-assembled monolayer of a hydrophilic spacer, or of a single-lipid monolayer on top of a self-assembled monolayer of a thiolipid, was realized by simply immersing the coated mercury electrode into an aqueous solution across a lipid film previously spread on its surface at its spreading pressure. Particularly stable mercury-supported lipid bilayers were obtained by using thiolipids. The biomimetic properties of these lipid bilayers were tested by incorporating channel-forming polypeptides (gramicidin and melittin) and proteins (OmpF porin). The effect of the transmembrane potential on the function of these channels was estimated by using a simple electrostatic model of the mercury -solution interphase. D

- by L. Becucci
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- Bioelectrochemistry, Electrochemistry, Crystallization, Ion Channels

An effective enzymatic glucose biosensorwas developed by immobilizing glucose oxidase on chitosan submicron
particles synthesized from the gladius of Todarodes pacificus (GCSP). The chemically synthesized chitosan from
gladius was pulverized to submicron particles by ball milling technique, which was further characterized and
compared with the standard chitosan (SCS). The degree of deacetylation of GCSP was determined using FTIR
spectroscopy which was comparable to the value of standard chitosan. The glucose oxidase (GOx) was
immobilized over GCSP on porous zinc oxide/platinum nanoparticle (ZnO/Pt) based electrode. The morphological
and structural properties of the electrodes were analyzed using scanning electron microscopy and X-ray diffraction
analysis. The glucose sensing behavior of electrode was estimated using electrochemical analysis and
showed an excellent analytical performance. The electrode ZnO/Pt/GCSP conjugated with GOx displayed high
sensitivity (88.76 μA mM−1 cm−2) with low detection limit in short response time. In addition, the very low
value ofMichaelis–Menten constant for GCSP based electrode contributes a better affinity of the electrode surface
towards glucose oxidase.

- by Anusha Raj
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- Bioelectrochemistry, Biosensors, Chitosan, Nanobiotechnology and Biosensors
- by Ricardo Quintero
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- Bioelectrochemistry

Present in all environments, microorganisms develop biofilms adjacent to the metallic structures creating corrosion conditions which may cause production failures that are of great economic impact to the industry. The most common practice in the oil and gas industry to annihilate these biofilms is the mechanical cleaning known as "pigging". In the present work, microorganisms from the "pigging" operation debris are tested biologically and electrochemically to analyse their effect on the corrosion of carbon steel. Results in the presence of bacteria display the formation of black corrosion products allegedly FeS and a sudden increase (more than 400 mV) of the corrosion potential of electrode immersed in artificial seawater or in field water (produced water mixed with aquifer seawater). Impedance tests provided information about the mechanisms of the interface carbon steel/ bacteria depending on the medium used: mass transfer limitation in artificial seawater was observed whereas that in field water was only charge transfer phenomenon. Denaturing Gradient Gel Electrophoresis (DGGE) results proved that bacterial diversity decreased when cultivating the debris in the media used and suggested that the bacteria involved in the whole set of results are mainly sulphate reducing bacteria (SRB) and some other bacteria that make part of the taxonomic order Clostridiales.

- by Omar Rosas
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- Bioelectrochemistry, Biofilms, Carbon, Corrosion

Interplay of charge between bacteria and electrode has led to emergence of bioelectrochemical systems which leads to applications such as production of electricity, wastewater treatment, bioremediation and production of value added products. Many electroactive bacteria have been identified that have unique external electron transport systems. Coupling of electron transport with carbon metabolism has opened a new approach of carbon dioxide sequestration. The electron transport mechanism involves various cellular and sub cellular molecules. The outer membrane cytochromes, Mtr-complex and Ech-Complex are few key molecules involved in electron transport in many electrogenic bacteria. Few cytochrome independent acetogenic electroactive bacteria were also discovered using Rnf complex to transport electrons. For improved productivity, an efficient bioreactor design is mandatory. It should encompass all certain critical issues such as microbial cell retention, charge dissipation, separators and simultaneous product recovery.

- by Shantonu Roy
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- Bioelectrochemistry

C/ Colom 1, 08222 Terrassa (Barcelona), Spain. Tl: 34 937398043.

- by Ester Guaus and +1
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- Bioelectrochemistry, Electrochemistry, Electrodes

Microelectronic devices that contain biological components are typically used to interrogate biology1,2 rather than control biological function. Patterned assemblies of proteins and cells have, however, been used for in vitro metabolic engineering3–7, where coordinated biochemical pathways allow cell metabolism to be characterized and potentially controlled8 on a chip. Such devices form part of technologies that attempt to recreate animal and human physiological functions on a chip9 and could be used to revolutionize drug development10. These ambitious goals will, however, require new biofabrication methodologies that help connect microelectronics and biological systems11,12 and yield new approaches to device assembly and communi- cation. Here, we report the electrically mediated assembly, interrogation and control of a multi-domain fusion protein that produces a bacterial signalling molecule. The biological system can be electrically tuned using a natural redox molecule, and its biochemical response is shown to provide the signalling cues to drive bacterial population behaviour. We show that the biochemical output of the system correlates with the electrical input charge, which suggests that electrical inputs could be used to control complex on-chip biological processes.

- by Hadar Ben-Yoav and +2
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- Bioelectrochemistry

Electroporation of cells is successfully used in biology, biotechnology and medicine. Practical problems still arise in the electroporation of cells in suspension. For example, the determination of cell electroporation is still a demanding and time-consuming task. Electric pulses also cause contamination of the solution by the metal released from the electrodes and create local enhancements of the electric field, leading to the occurrence of electrochemical reactions at the electrode/electrolyte interface. In our study, we investigated the possibility of assessing modifications to the cell environment caused by pulsed electric fields using electrochemical impedance spectroscopy. We designed an experimental protocol to elucidate the mechanism by which a pulsed electric field affects the electrode state in relation to different electrolyte conductivities at the interface. The results show that a pulsed electric field affects electrodes and its degree depends on the electrolyte conduct...

- by Nader Yourdshahi
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- Engineering, Analytical Chemistry, Bioelectrochemistry, Electrochemistry

Electrode surface characteristics represent an important aspect on the construction of sensitive DNA electrochemical biosensors for rapid detection of DNA interaction and damage. Two different immobilization procedures of double-stranded DNA (dsDNA) at the surface of a HOPG electrode were evaluated by MAC mode AFM performed in air. A thin dsDNA adsorbed film forming a network structure with holes exposing the electrode surface and a thick dsDNA film completely covering the electrode surface, presenting a much rougher structure, were investigated. The DNA surface characteristics and structure are discussed with respect to the degree of surface coverage. D

- by Zlatko Rakocevic
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- Bioelectrochemistry, Electrochemistry, Carbon, Crystallization

Among the most pressing energy and environmental strategic challenges today is to identify and deploy viable alternatives to fossil-fuel-based energy systems The barriers to deployment are systematic, leading to a state of affairs described as ‘carbon lock-in’ (Unruh
2000; Neuhoff 2007). Simply stated, even if alternative energy systems are cost-competitive in theory, the prime movers that control their diffusion throughout society –
for example, conversion and distribution infrastructure; financing mechanisms; skilled labour force; attitudes toward particular kinds of energy production activities and energy services – exhibit a preference for incumbent carbon-intensive fossil energy resources. Carbon lock-in represents path dependencies within energy systems including sunk-cost in prevailing infrastructure and entrenched political interests along with positively reinforcing relationships with broader system dynamics, from global financial logics that continue to monetise unburned carbon through energy
futures contracts to our everyday practices and expectations about mobility, comfort, and overall
well-being that underpin regular visits to the gasoline station. All of this is to say that energy systems are sociotechnical in nature, characterised by deep and often subtle interdependencies between technological, social, political-economic, and cultural processes which operate across the energy supply chain and at all scales of energy system operation (Miller, Richter, and O’Leary 2015).

- by Kean Birch
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- Bioengineering, Geography, Human Geography, Political Geography and Geopolitics

. The electrochemical treatment EChT of tumours implies that tumour tissue is treated with a continuous direct current through two or more electrodes placed in or near the tumour. The treatment offers considerable promise of a safe, simple and relatively noninvasive anti-tumour therapy for treatment of localised malignant as well as benign tumours. Although more than 10 000 patients have been treated in China during the past 10 years, EChT has not yet been universally accepted. The reason for this is the lack of essential preclinical studies and controlled clinical trials. Uncertainties regarding the destruction mechanism of EChT also hinder the development of an optimised and reliable dose-planning methodology. This article reviews the collected Chinese and occidental experiences of the electrochemical treatment of tumours, alone and in combination with other therapies. The current knowledge of the destruction mechanism underlying EChT is presented along with different approaches towards a dose planning methodology. In addition, we discuss our view of different important parameters that have to be accounted for, if clinical trials are to be initiated outside of China. q 2000 Elsevier Science S.A. All rights reserved.

- by Ingemar Naslund
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- Bioelectrochemistry, Clinical Trial, Electrochemistry, Cancer

Some metal ions play a cofactor role for the activity of tyrosinase enzyme and one of them is copper ion. In this study an amperometric biosensor was developed in order to investigate the effect of the copper ions on the activity of tyrosinase enzyme. In the construction of the biosensor tyrosinase enzyme was immobilized on a Clark-type dissolved oxygen probe which was covered with a oxygen sensitive teflon membrane, by using a chemical covalent immobilization method based on gelatine and bifunctional reagent, glutaraldehyde. The principle of the measurement was based on the determination of the differentiation of dissolved oxygen level in the enzymatic reaction catalyzed by tyrosinase in the absence and the presence of copper ions. Differences between the dissolved oxygen concentrations were related to copper ion concentration which was added in to the reaction medium. The biosensor response depends linearly on copper ion concentration between 2.5-20.0 μM with a response time 1 min. The detection limit of the biosensor is 0.95 μM.

- by Erol Akyilmaz
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- Bioelectrochemistry, Electrochemistry, Linear models, Copper

Au nanocorals are grown on gold screen-printed electrodes (SPEs) by using a novel and simple one-step electro-deposition process. Scanning electron microscopy was used for the morphological characterization. The devices were assembled on a three-electrode SPE system, which is flexible and mass producible. The electroactive surface area, determined by cyclic voltammetry in sulphuric acid, was found to be 0.07 ± 0.01 cm 2 and 35.3 ± 2.7 cm 2 for bare Au and nanocoral Au, respectively. The nanocoral modified SPEs were used to develop an enzymatic glucose biosensor based on H 2 O 2 detection. Au nanocoral electrodes showed a higher sensitivity of 48.3 ± 0.9 μA/ (mM cm 2) at +0.45 V vs Ag|AgCl compared to a value of 24.6 ± 1.3 μA/(mM cm 2) at +0.70 V vs Ag|AgCl obtained with bare Au electrodes. However, the modified electrodes have indeed proven to be extremely powerful for the direct detection of glucose with a non-enzymatic approach. The results confirmed a clear peak observed by using nanocoral Au electrode even in the presence of chloride ions at physiological concentration. Amperometric study carried out at + 0.15 V vs Ag | AgCl in the presence of 0.12 M NaCl showed a linear range for glucose between 0.1 and 13 mM.

- by Lo Gorton and +1
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- Bioelectrochemistry

Numerous experimental evidence show that exposure of biological systems to extremely high frequency microwaves may induce significant effects even at low powers. These effects are thought to occur via nonthermal mechanisms involving primarily the interaction of microwaves with phospholipid membrane structures. However, no conclusive experimental evidence that biomembranes exhibit remarkable sensitivity to this radiation has been provided up to now. Here, deuterium nuclear magnetic resonance spectroscopy is used to study the effects of microwaves on 1,2-Dimyristoyl-sn-glycero-3-phosphatidylcholine/ 2 H 2 O multilamellar vesicles that serve as biomimetic membranes. Here we show that, if the membrane is brought into close proximity to the transition point, microwaves induce a reduction of water ordering at the membrane interface, an upward shift of the main phase transition temperature and a broadening of the transition region. A deep dosimetric analysis shows that the above effects are nonthermal, indicating the need for a nonthermal hypothesis to explain them. This study suggests that exposure to high-frequency microwaves can have far reaching consequences on active biological systems.

- by Amerigo Beneduci and +2
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- Bioelectrochemistry, NMR Spectroscopy, High Frequency, Temperature

- by Eva Nilsson
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- Bioelectrochemistry, Clinical Trial, Electrochemistry, Cancer

The change of the pH of a NaCl solution (139 -149 mM NaCl) buffered with 5 -15 mM sodium phosphates (pH 7.4) during electromanipulation was studied. It has been determined that an increase in the pH value of electroporation solution of a whole chamber volume, caused by the application of electric field pulses, commonly used in cell electromanipulation procedures, can exceed 1 -2 pH units.

- by Gintautas Saulis
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- Bioelectrochemistry, Electricity, High Voltage, Copper

Nano-structured bismuth oxide (nano-BiO x ) is a suitable material for enzyme immobilization owing to its attractive properties, such as large specific surface area, suitable permeability of the resulting film, the high biocompatibility, and as well as photovoltaic effect from semiconductor nanoparticles. Thus, a new type of amperometric glucose biosensor based on nano-BiO x was constructed. The amperometric detection of glucose was assayed by potentiostating the GOD/nano-BiO x electrode at 0.5 V to oxidize the enzymatically generated hydrogen peroxide. The proposed biosensor provided a linear response to glucose over a concentration range of 1 × 10 − 6 M to 1.5 × 10 − 3 M with a sensitivity of 51.0 ± 0.4 mA/(M cm 2 ) and a detection limit of 4 × 10 − 7 M based on S/N = 3. The apparent Michaelis-Menten constant was calculated to be 2.9 × 10 − 3 M. In addition, characterization of nano-BiO x and modified electrode was performed by FT-IR spectroscopy, Raman spectroscopy, scanning electron microscope (SEM) and rotating-disk electrode (RDE) voltammetry.

- by Serge Cosnier
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- Bioelectrochemistry, Electrochemistry, Scanning Electron Microscopy, Glucose

Broad application of microbial fuel cells (MFCs) requires low cost and high operational sustainability. Microbial-cathode MFCs, or cathodes using only bacterial catalysts (biocathodes), can satisfy these demands and have gained considerable attention in recent years. Achievements with biocathodes over the past 3–4years have been particularly impressive not only with respect to the biological aspects but also the system-wide considerations related

- by John Regan
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- Chemistry, Bioelectrochemistry, Catalysis, Multidisciplinary

Electrochemically produced graft copolymers of thiophene capped polytetrahydofuran (TPTHF1 and TPTHF2) and pyrrole were achieved by constant potential electrolysis using sodium dodecylsulfate (SDS) as the supporting electrolyte. Characterizations were based on Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Electrical conductivities were measured by the four-probe technique.

- by Levent Toppare
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- Bioelectrochemistry, Electrochemistry, Scanning Electron Microscopy, Polymers

To date, a number of researchers are seeking for and/or designing novel molecules which function as arithmetic molecular engines. Biomolecules such as deoxyribonucleic acid (DNA) and proteins are examples of promising candidate molecules. In the present article, we showed our view that DNA-based molecules could be used as a novel class of platforms for discrete mathematical operations or tools for natural computation. Here, we report on a novel molecular logic circuit combining exclusive disjunction (XOR) gate and conjunction (AND) gate implemented on a single DNA molecule performing arithmetic operations with simple binary numbers through polymerase chain reactions (PCR); which was inspired by previously developed protein-based computing model allowing simple polynomial algebra over fields through algebraic representation of cyclic inter-conversions in the catalytic modes of a plant enzyme as a cyclic additive group. In addition, we showed that DNA can be used as the platform for image coding and processing leading to DNA-coded animation by using novel PCR-based protocols. Lastly, we discussed the significance of recent attempts in the stream of natural computing and synthetic biological research, by handling DNA and related biomolecules as the media for discrete mathematical operations.

- by Tomonori Kawano
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- Information Systems, Bioengineering, Biochemistry, Bioinformatics

Biofilms formed in aerobic seawater on stainless steel are known to be efficient catalysts of the electrochemical reduction of oxygen. Based on their genomic analysis, seven bacterial isolates were selected and a cyclic voltammetry (CV) procedure was implemented to check their electrocatalytic activity towards oxygen reduction. All isolates exhibited close catalytic characteristics. Comparison between CVs recorded with glassy carbon and pyrolytic graphite electrodes showed that the catalytic effect was not correlated with the surface area covered by the cells. The low catalytic effect obtained with filtered isolates indicated the involvement of released redox compounds, which was confirmed by CVs performed with adsorbed iron-porphyrin. None of the isolates were able to form electro-active biofilms under constant polarization. The capacity to catalyze oxygen reduction is shown to be a widespread property among bacteria, but the property detected by CV does not necessarily confer the ability to achieve stable oxygen reduction under constant polarization.

- by Christine Roques
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- Bioelectrochemistry, Biofilms, Electrochemistry, Catalysis

In this work studies on rapid inhibitory interactions between heavy metals and photosynthetic materials at different organization levels were carried out by optical assay techniques, investigating the possibility of applications in the heavy metal detection field. Spinach chloroplasts, thylakoids and Photosystem II proteins were employed as biotools in combination with colorimetric assays based on dichlorophenol indophenole (DCIP) photoreduction and on

- by Lucia Catucci
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- Bioelectrochemistry, Pigmentation, Colorimetry, Photosynthesis