Chang-Ho Han, Hyunsu Ha, Jaesung Jang

Lab on a Chip • 2019

An array of microfabricated interdigitated electrodes (IDEs) is one of the most commonly used forms of electrode geometry for dielectrophoretic manipulation of biological particles in microfluidic biochips owing to simplicity of fabrication and ease of analysis. However, the dielectrophoretic force dramatically reduces as the distance from the electrode surface increases; therefore, the effective region is usually close to the electrode surface for a given electric potential difference. Here, we present a novel two-dimensional computational method for generating planar electrode patterns with enhanced volumetric electric fields, which we call the "microelectrode discretization (MED)" method. It involves discretization and reconstruction of planar electrodes followed by selection of the electrode pattern that maximizes a novel objective function, factor S, which is determined by the electric potentials on the electrode surface alone. In this study, IDEs were used as test planar electrodes. Two arrays of IDEs and respective MED-optimized electrodes were implemented in microfluidic devices for the selective capture of Escherichia coli against 1 μm-diameter polystyrene beads, and we experimentally observed that 1.4 to 35.8 times more bacteria were captured using the MED-optimized electrodes than the IDEs (p < 0.0016), with a bacterial purity against the beads of more than 99.8%. This simple design method offered simplicity of fabrication, highly enhanced electric field, and uniformity of particle capture, and can be used for many dielectrophoresis-based sensors and microfluidic systems.

Lizeng Zuo, W. Fan, Youfang Zhang et al.

Nanoscale • 2017

Electroactive materials, such as nickel sulfide (NiS), with high theoretical capacities have attracted broad interest to fabricate highly efficient supercapacitors. Preventing aggregation and increasing the conductivity of NiS particles are key challenging tasks to fully achieve excellent electrochemical properties of NiS. One effective approach to solve these problems is to combine NiS with highly porous and conductive carbon materials such as carbon aerogels. In this study, a green and facile method for the in situ growth of NiS particles on bacterial cellulose (BC)-derived sheet-like carbon aerogels (CAs) has been reported. CA prepared by the dissolution-gelation-carbonization process was used as a framework to construct NiS/CA composite aerogels with NiS uniformly decorated on the pore walls of CA. It was found that the NiS/CA composite aerogel electrodes exhibit excellent capacitive performance with high specific capacitance (1606 F g-1), good rate capacitance retention (69% at 10 A g-1), and enhanced cycling stability (91.2% retention after 10 000 continuous cyclic voltammetry cycles at 100 mV s-1). Furthermore, asymmetric supercapacitors (ASCs) were constructed utilizing NiS/CA composite and CA as the positive and negative electrode materials, respectively. Through the synergistic effect of three-dimensional porous structures and conductive networks derived from CA and the high capacitive performance offered by NiS, the ASC device exhibited an energy density of ∼21.5 Wh kg-1 and a power density of 700 W kg-1 at the working voltage of 1.4 V in 2 M KOH aqueous solution. The ASC device also showed excellent long-term cycle stability with ∼87.1% specific capacitance retention after 10 000 cycles of cyclic voltammetry scans. Therefore, the NiS/CA composite shows great potential as a promising alternative to high-performance electrode materials for supercapacitors.

Jun Xing, S. Qi, Zhengao Wang et al.

Advanced Functional Materials • 2019

Conductive polymer electrodes are widely used for electrical signal detection owing to their unique mechanical, redox, and impedance characteristics. However, the performance of electrodes is compromised due to the interference of adhered bacteria and most of the scientists have not taken the microbial environment into consideration during electrode design. Here, a facile approach to construct antimicrobial peptide (AMP) functionalized polypyrrole nanowire array conductive electrodes (PNW‐AMP) is reported. Instead of compromising the electrochemical properties as the other antibacterial agents do, the PNW‐AMP electrodes exhibit excellent redox and low interfacial impedance properties. More importantly, the PNW‐AMP can eliminate bacterial adhesion and maintain electrochemical stability simultaneously in the microbial microenvironment for a long time. The antibacterial rate of the PNW‐AMP electrode reaches 95.8% after exposing the electrode to air for one month, while the charge transfer resistance ( Rct) value only increases by 9% at a bacterium (Escherichia. Coli ) concentration of 1 × 104 colony forming unit (CFU) mL−1. This research makes it possible to construct highly stable conductive polymer electrodes for bacterial environment electrical signal detection.

G. Ihn, S. T. Woo, Moo-jeong Sohn et al.

Analytical Letters • 1989

Abstract A bacterial electrode for the determination of urea has been constructed by immobilizing the Proteus mirabilis on a carbon dioxide gas-sensor. the electrode gave a Nernstian behaviour between 7.0 × 10−4 and 3.0 × 10−2 M urea with a slope of 46 mV/decade in pH 6.80, 0.1M phosphate buffer at 30°C. the important interferences were L-asparagine, cytosine, inositol and phenol, and most inorganic salts reacted as the inhibitor. This electrode showed little change in the response and linear rane for 7 days, and could also be used in the linear range because the electrode had good reproducibility even after this. This device could be used as easily and exactly as a spectrophotometric method in clinical applications.

Yi-Ru Luo, Wenxiu Que, Yi Tang et al.

ACS Nano • 2024

Ultrathin MXene-based films exhibit superior conductivity and high capacitance, showing promise as electrodes for flexible supercapacitors. This work describes a simple method to enhance the performance of MXene-based supercapacitors by expanding and stabilizing the interlayer space between MXene flakes while controlling the functional groups to improve the conductivity. Ti3C2Tx MXene flakes are treated with bacterial cellulose (BC) and NaOH to form a composite MXene/BC (A-M/BC) electrode with a microporous interlayer and high surface area (62.47 m2 g-1). Annealing the films at low temperature partially carbonizes BC, increasing the overall electrical conductivity of the films. Improvement in conductivity is also attributed to the reduction of -F, -Cl, and -OH functional groups, leaving -Na and -O functional groups on the surface. As a result, the A-M/BC electrode demonstrates a capacitance of 594 F g-1 at a current density of 1 A g-1 in 3 M H2SO4, which represents a ∼2× increase over similarly processed films without BC (309 F g-1) or pure MXene (298 F g-1). The corresponding device has an energy density of 9.63 Wh kg-1 at a power density of 250 W kg-1. BC is inexpensive and enhances the overall performance of MXene-based film electrodes in electronic devices. This method underscores the importance of functional group regulation in enhancing MXene-based materials for energy storage.

Likkhasit Wannasen, E. Swatsitang, S. Pinitsoontorn

International Journal of Energy Research • 2020

A flexible electrode of NH4CoPO4 · H2O composite bacterial cellulose (Co‐BC) has been successfully prepared via a hydrothermal method. A bacterial cellulose (BC) membrane was used as a host matrix for nanocrystalline (NC) NH4CoPO4 · H2O. The preparation process included anchoring nanocrystalline NH4CoPO4 · H2O on BC nanofibers with an intrinsic 3D network structure. X‐ray diffraction (XRD) results indicated the orthorhombic structure of the NH4CoPO4 · H2O NC within the Pmn21 space group and BC of a Type‐I structure. FE‐SEM images revealed microplate‐like NH4CoPO4 · H2O structures on BC nanofibers. The a three‐electrode system of all samples were studied for their electrochemical properties by CV, charge/discharge and EIS estimations in a 3 M KOH electrolyte. A maximal specific area capacitance of 158.5 mF cm−2 (43.3 F g−1) was obtained at a current density of 0.25 mA cm−2 using a Co‐BC90 electrode. Moreover, this sample show an excellent capacitance retention of 99% after a 3000 cycle at 1 mA cm−2 current density.

Anjana Ratheesh, L. Elias, Sheik Muhammadhu Aboobakar Shibli

ACS Applied Bio Materials • 2021

The study of bacterial adhesion and its consequences has great significance in different fields such as marine science, renewable energy sectors, soil and plant ecology, food industry, and the biomedical field. Generally, the adverse effects of microbial surface interactions have attained wide visibility. However, herein, we present distinct approaches to highlight the beneficial aspects of microbial surface interactions for various applications rather than deal with the conventional negative aspects or prevention strategies. The surface microbial reactions can be tuned for useful biochemical or bio-electrochemical applications, which are otherwise unattainable through conventional routes. In this context, the present review is a comprehensive approach to highlight the basic principles and signature parameters that are responsible for the useful microbial-electrode interactions. It also proposes various surface tuning strategies, which are useful for tuning the electrode characteristics particularly suitable for the enhanced bacterial adhesion and reactions. The tuning of surface characteristics of electrodes is discussed with a special reference to the Microbial Fuel Cell as an example.

Xiaolong Li, Libei Yuan, Rong Liu et al.

Advanced Energy Materials • 2021

The fabrication of highly durable, flexible, all‐solid‐state supercapacitors (ASCs) remains challenging because of the unavoidable mechanical stress that such devices are subjected to in wearable applications. Natural/artificial fiber textiles are regarded as prospective materials for flexible ASCs due to their outstanding physicochemical properties. Here, a high‐performance ASC is designed by employing graphene‐encapsulated polyester fiber loaded with polyaniline as the flexible electrodes and bacterial cellulose (BC) nanofiber‐reinforced polyacrylamide as the hydrogel electrolyte. The ASC combines the textile electrode capable of arbitrary deformation with the BC‐reinforced hydrogel with high ionic conductivity (125 mS cm−1), high tensile strength (330 kPa), and superelasticity (stretchability up to ≈1300%), giving rise to a device with high stability/compatibility between the electrodes and electrolyte that is compliant with flexible electronics. As a result, this ASC delivers high areal capacitance of 564 mF cm−2, excellent rate capability, good energy/power densities, and more importantly, superior mechanical properties without significant capacitance degradation after repeated bending, confirming the functionality of the ASC under mechanical deformation. This work demonstrates an effective design for a sufficiently tough energy storage device, which shows great potential in truly wearable applications.

Kunpeng Gao, Nailong Wu, Bowen Ji et al.

Sensors • 2023

In this paper, we present a soft and moisturizing film electrode based on bacterial cellulose and Ag/AgCl conductive cloth as a potential replacement for gel electrode patches in electroencephalogram (EEG) recording. The electrode materials are entirely flexible, and the bacterial cellulose membrane facilitates convenient adherence to the skin. EEG signals are transmitted from the skin to the bacterial cellulose first and then transferred to the Ag/AgCl conductive cloth connected to the amplifier. The water in the bacterial cellulose moisturizes the skin continuously, reducing the contact impedance to less than 10 kΩ, which is lower than commercial gel electrode patches. The contact impedance and equivalent circuits indicate that the bacterial cellulose electrode effectively reduces skin impedance. Moreover, the bacterial cellulose electrode exhibits lower noise than the gel electrode patch. The bacterial cellulose electrode has demonstrated success in collecting α rhythms. When recording EEG signals, the bacterial cellulose electrode and gel electrode have an average coherence of 0.86, indicating that they have similar performance across different EEG bands. Compared with current mainstream conductive rubber dry electrodes, gel electrodes, and conductive cloth electrodes, the bacterial cellulose electrode has obvious advantages in terms of contact impedance. The bacterial cellulose electrode does not cause skin discomfort after long-term recording, making it more suitable for applications with strict requirements for skin affinity than gel electrode patches.

Qijing Liu, Wenliang Xu, Qinran Ding et al.

Advanced Science • 2024

Interfacial electron transfer between electroactive microorganisms (EAMs) and electrodes underlies a wide range of bio‐electrochemical systems with diverse applications. However, the electron transfer rate at the biotic‐electrode interface remains low due to high transmembrane and cell‐electrode interfacial electron transfer resistance. Herein, a modular engineering strategy is adopted to construct a Shewanella oneidensis‐carbon felt biohybrid electrode decorated with bacterial cellulose aerogel‐electropolymerized anthraquinone to boost cell‐electrode interfacial electron transfer. First, a heterologous riboflavin synthesis and secretion pathway is constructed to increase flavin‐mediated transmembrane electron transfer. Second, outer membrane c‐Cyts OmcF is screened and optimized via protein engineering strategy to accelerate contacted‐based transmembrane electron transfer. Third, a S. oneidensis‐carbon felt biohybrid electrode decorated with bacterial cellulose aerogel and electropolymerized anthraquinone is constructed to boost the interfacial electron transfer. As a result, the internal resistance decreased to 42 Ω, 480.8‐fold lower than that of the wild‐type (WT) S. oneidensis MR‐1. The maximum power density reached 4286.6 ± 202.1 mW m−2, 72.8‐fold higher than that of WT. Lastly, the engineered biohybrid electrode exhibited superior abilities for bioelectricity harvest, Cr6+ reduction, and CO2 reduction. This study showed that enhancing transmembrane and cell‐electrode interfacial electron transfer is a promising way to increase the extracellular electron transfer of EAMs.

R. Maallah, A. Chtaini

Pharmaceutica Analytica Acta • 2018

Voltametric degradation of phenol was carried out at microbial electrode. This electrode is based on graphite carbon and natural phosphate modified by bacteria inserted in the phosphate matrix, the whole is covered by a polymer developed in situ on the surface. This electrode, designated subsequently by bacteria-NP-CPE, Showed stable response and was characterized with voltametric methods, as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experimental results revealed that the prepared electrode could be a feasible for degradation of hazardous phenol pollutants.

Young‐Hoo Kim, Saerom Park, Keehoon Won et al.

Journal of Chemical Technology &amp; Biotechnology • 2013

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p><jats:bold>Bacterial cellulose (<jats:styled-content style="fixed-case">BC</jats:styled-content>)‐based materials have many potential applications in the biomedical field because of their inherent biocompatibility. Carbon nanotubes (<jats:styled-content style="fixed-case">CNTs</jats:styled-content>) have been used as electrode materials owing to their high electrical conductivity. In this study, <jats:styled-content style="fixed-case">BC‐CNT</jats:styled-content> composite electrodes were prepared simply by directly filtering <jats:styled-content style="fixed-case">CNTs</jats:styled-content> through <jats:styled-content style="fixed-case">BC</jats:styled-content> hydrogel and vacuum drying the <jats:styled-content style="fixed-case">BC</jats:styled-content> hydrogel containing the <jats:styled-content style="fixed-case">CNTs</jats:styled-content>. Glucose oxidase (<jats:styled-content style="fixed-case">GOx</jats:styled-content>) was immobilized on <jats:styled-content style="fixed-case">BC‐CNT</jats:styled-content> composite electrodes.</jats:bold></jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p><jats:bold>Cyclic voltammograms revealed that the <jats:styled-content style="fixed-case">BC‐CNT‐GOx</jats:styled-content> electrodes had a pair of well‐defined peaks. The formal redox potential peak was –496 <jats:styled-content style="fixed-case">mV</jats:styled-content> (vs. Ag/<jats:styled-content style="fixed-case">AgCl</jats:styled-content>), which agreed well with that of <jats:styled-content style="fixed-case">FAD</jats:styled-content>/<jats:styled-content style="fixed-case">FADH<jats:sub>2</jats:sub></jats:styled-content>. This result clearly indicates that direct electron transfer occurred between <jats:styled-content style="fixed-case">GOx</jats:styled-content> and the <jats:styled-content style="fixed-case">BC‐CNT</jats:styled-content> composite electrode. In addition, the <jats:styled-content style="fixed-case">GOx</jats:styled-content> immobilized on the electrode retained its catalytic ability to oxidize glucose.</jats:bold></jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p><jats:bold>Conductive <jats:styled-content style="fixed-case">BC‐CNT</jats:styled-content> composite films form a good biocompatible electrode for the direct electron transfer of glucose oxidase. They have many potential applications in the biomedical field such as biosensors, biofuel cells, and bioelectronic devices. © 2012 Society of Chemical Industry</jats:bold></jats:p></jats:sec>

Min-Jeong Seong, Kyu-Ri Park, S. J. Kim et al.

Physics of Plasmas • 2025

<jats:p>A diffuse and large-area dielectric barrier discharge (DBD) filled with air and helium gas mixtures was generated by a unipolar nanosecond-pulsed high voltage. A large-gap multiple pin-to-plate electrode was employed to facilitate the insertion of well plates into the plasma discharge. The nanosecond high-voltage-pulsed discharge has unique advantages in producing a diffuse DBD plasma. We examined the changes in the plasma properties upon varying operating parameters such as the gas composition and flow rate, as well as the pulse voltage. Various types of liquid (de-ionized, tap, and saline water, as well as phosphate buffered saline and LB broth) were exposed to the DBD plasma. The physicochemical properties (pH and electrical conductivity) and concentrations of reactive species generated in the treated liquids (such as H2O2, NO2−, and O3, which play central roles in the aqueous-phase chemistry of plasma-treated liquids for bacterial inactivation) were measured as a function of the operating parameters. The nanosecond-pulsed DBD was observed to generate significantly higher level of reactive species in various types of liquid. For investigating the plasma treatment of liquids containing suspended microorganisms, 1 ml of Escherichia coli (E. coli) stock suspension was pipetted into 9 ml of DW. The resulting bacterial suspensions were treated with the DBD plasma for a selected time. Six-log E. coli reduction was achieved after 19 h of incubation. A DBD plasma generated in a gas mixture of ambient air and 2 slm helium exhibited an enhanced inactivation efficacy, which was correlated with the RONS concentration and pH in the plasma-treated liquids.</jats:p>

M. A. Karmali, A. Williams, P. C. Fleming et al.

Journal of Hygiene • 1984

<jats:title>Summary</jats:title><jats:p>A method using an ammonia electrode is being developed for investigating the deamination of amino acids and amides by bacteria. Application of this method to<jats:italic>Campylobacter jejuni</jats:italic>and<jats:italic>C. coli</jats:italic>has led to the demonstration of<jats:italic>d</jats:italic>-asparaginase activity in some strains. This has allowed the subdivision of both species into<jats:italic>d</jats:italic>-asparaginase-positive and -negative biotypes. Even though the method is in the developmental stage, it was found to be generally reproducible and easy to perform. Areas for further improving the procedure have been identified. The ammonia electrode offers the theoretical possibility of investigating the breakdown of any amino acid by bacteria. It thus opens up a new and practical approach for separating species and strains, particularly in those bacterial groups that are difficult to subdivide by conventional means.</jats:p>

A. C. Fisher

• 1996

<p> <italic>Electrode Dynamics</italic> provides an introduction to the field of electrode dynamics. The word electrochemistry commonly instils fear in students. This text aims to distil this fear with a gentle introduction to the kinetics of electron transfer reactions, and explores the potential applications of electrochemistry methodology. The early chapters provide a general introduction to the factors which control the rate of an electrode reaction. The later chapters deal with a variety of electrochemical applications including the study of surface processes, reaction mechanisms, electrosynthesis and the combination of electrochemistry with complementary techniques such as spectroscopy.</p>

R.G. KROLL, EMMA R. FREARS, ANITA BAYLISS

Journal of Applied Bacteriology • 1989

<jats:p>An oxygen electrode‐based assay of catalase was developed as a simple method of assessing contamination by bacteria capable of respiration. The method gave a rapid and reasonable quantification of cell numbers in pure cultures and was able to detect 10<jats:sup>3</jats:sup> bacteria/ml in some cases. The sensitivity of the method was dependent on the identity of the culture and when applied to foods the sensitivity was reduced due to the presence of non‐microbial catalase. The use of electropositively charged filters to remove the organisms from the food sample improved the sensitivity and the relationship between catalase activity and cell numbers in some foods.</jats:p>

Mohamed Ghazi Al-Fandi, Nid’a Hamdan Alshraiedeh, Rami Joseph Oweis et al.

Sensor Review • 2018

<jats:sec> <jats:title content-type="abstract-subheading">Purpose</jats:title> <jats:p>This paper aims to report a prototype of a reliable method for rapid, sensitive bacterial detection by using a low-cost zinc oxide nanorods (ZnONRs)-based electrochemical sensor.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Design/methodology/approach</jats:title> <jats:p>The ZnONRs have been grown on the surface of a disposable, miniaturized working electrode (WE) using the low-temperature hydrothermal technique. Scanning electron microscopy and energy dispersion spectroscopy have been performed to characterize the distribution as well as the chemical composition of the ZnONRs on the surface, respectively. Moreover, the cyclic voltammetry test has been implemented to assess the effect of the ZnONRs on the signal conductivity between −1 V and 1 V with a scan rate of 0.01 V/s. Likewise, the effect of using different bacterial concentrations in phosphate-buffered saline has been investigated.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Findings</jats:title> <jats:p>The morphological characterization has shown a highly distributed ZnONR on the WE with uneven alignment. Also, the achieved response time was about 12 minutes and the lower limit of detection was approximately 103 CFU abbreviation for Colony Forming Unit/mL.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Originality/value</jats:title> <jats:p>This paper illustrates an outcome of an experimental work on a ZnONRs-based electrochemical biosensor for direct detection of bacteria.</jats:p> </jats:sec>

S. Zamani, Kh. Ghanbari, S. Bonyadi

Analytical Methods • 0

<jats:p>Metformin is widely used in the treatment of diabetes either alone or in combination with other drugs. Measuring the concentration of this substance is very important both pre-clinically and clinically in the medical monitoring of diabetic patients.</jats:p>

Palaniappan Ramasamy, Gajalakshmi Dakshinamoorthy, Shanmugam Jayashree et al.

Biosensors • 0

<jats:p>Salmonellosis caused by Salmonella sp. has long been reported all over the world. Despite the availability of various diagnostic methods, easy and effective detection systems are still required. This report describes a dialysis membrane electrode interface disc with immobilized specific antibodies to capture antigenic Salmonella cells. The interaction of a specific Salmonella antigen with a mouse anti-Salmonella monoclonal antibody complexed to rabbit anti-mouse secondary antibody conjugated with HRP and the substrate o-aminophenol resulted in a response signal output current measured using two electrode systems (cadmium reference electrode and glassy carbon working electrode) and an agilent HP34401A 6.5 digital multimeter without a potentiostat or applied potential input. A maximum response signal output current was recorded for various concentrations of Salmonella viz., 3, 30, 300, 3000, 30,000 and 300,000 cells. The biosensor has a detection limit of three cells, which is very sensitive when compared with other detection sensors. Little non-specific response was observed using Streptococcus, Vibrio, and Pseudomonas sp. The maximum response signal output current for a dialysis membrane electrode interface disc was greater than that for gelatin, collagen, and agarose. The device and technique have a range of biological applications. This novel detection system has great potential for future development and application in surveillance for microbial pathogens.</jats:p>

Soheila Ebrahimi-Koodehi, Farhad Esmaeili Ghodsi, Jamal Mazloom

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>Recently, metal–organic frameworks (MOFs) and hybrids with biomaterial are broadly investigated for a variety of applications. In this work, a novel dual-phase MOF has been grown on bacterial cellulose (BC) as a biopolymer nano-fibrous film (Ni/Mn-MOF@BC), and nickel foam (Ni/Mn-MOF@NF) using a simple reflux method to explore their potential for photocatalyst and energy storage applications. The studies showed that the prepared Mn and Ni/Mn-MOFs display different structures. Besides, the growth of MOFs on BC substantially changed the morphology of the samples by reducing their micro sized scales to nanoparticles. The nanosized MOF particles grown on BC served as a visible-light photocatalytic material. Regarding the high surface area of BC and the synergistic effect of two metal ions, Ni/Mn-MOF@BC with a lower band gap demonstrates remarkable photocatalytic degradation efficiency (ca. 84% within 3 h) against methylene blue (MB) dye under visible light, and the catalyst retained 65% of its initial pollutant removal properties after four cycles of irradiation. Besides, MOF powders deposited on nickel foam have been utilized as highly capacitive electrochemical electrodes. There, Ni/Mn-MOF@NF electrode also possesses outstanding electrochemical properties, showing a specific capacitance of 2769 Fg<jats:sup>−1</jats:sup> at 0.5 Ag<jats:sup>−1</jats:sup>, and capacity retention of 94% after 1000 cycles at 10 Ag<jats:sup>−1</jats:sup>.</jats:p>

Wenjia Zhang, Hongkai Wu, I‐Ming Hsing

Electroanalysis • 2015

<jats:title>Abstract</jats:title><jats:p>Formation of biofilm on an electrode surface is usually a prerequisite for efficient electron transfer from electrogenic bacteria onto electrode, and the geometric status of the biofilm governs the generated current. In this study, we propose a real‐time characterization method to track the dynamic formation process of biofilm on electrode using scanning electrochemical microscopy (SECM). <jats:italic>Shewanella oneidensis</jats:italic> MR‐1 was chosen in this work as an electrogenic model species. A plane electrode at the bottom of a electrochemical cell filled with bacteria suspension was biased at +0.04 V vs. Ag/AgCl as the sole electron acceptor under anaerobic environment, while a movable ultramicroelectrode (UME) was employed to track the localized faradaic current generated by a redox mediator, Ru(NH<jats:sub>3</jats:sub>)<jats:sub>6</jats:sub>Cl<jats:sub>3</jats:sub> above the bottom electrode. The growth rate of biofilm showed some spatial heterogeneity, which might be explained by inhomogeneous mass transfer and non‐uniformity of electrode surface. The application of SECM into bacterial electrogenesis studies offered a simple and label‐free monitoring method to evaluate the bacteria‐electrode coupling status.</jats:p>

SONTHAYA NUMTHUAM, PHUNSIRI SUTHILUK, TAKAAKI SATAKE

Journal of Food Safety • 2011

<jats:sec><jats:title>ABSTRACT</jats:title><jats:p>The use of dissolved oxygen (DO) electrode to determine the total number of bacterial contamination in foods was investigated. The DO in food extract solution was measured as the electrical current continuously for 2 h at 30C. The rate of current decrease serves as a potential index for the prediction of bacterial contamination. The additional culture media is necessary for an effective determination of bacteria in shredded cabbage, cooked rice and instant cream sauce samples. The high prediction accuracies (<jats:italic>r</jats:italic> ≥ 0.90) were achieved for all sample types when the analysis period was 2 h. The measurement of DO using oxygen electrode provides a rapid and convenient method for the determination of bacteria in foods.</jats:p></jats:sec><jats:sec><jats:title>PRACTICAL APPLICATIONS</jats:title><jats:p>In comparison with the traditional microbiological method, the present research could provide more rapid and simple measuring method to improve the existing security level in food process. In order to support the food industry and market needs, the development of the measuring method to be more simple, portable and inexpensive method was considered. The results obtained from this study were considered to be important basic information for the application to the sophisticated technique as the micro total analysis system or the lab‐on‐chip. Therefore, in further study, the micro‐electro‐mechanical system that facilitates accurate and economic analysis of a sample to be tested for practical use in the real market will be developed. We think that the microchip‐type oxygen sensor developed will become a powerful tool for the determination of total aerobic bacterial contamination in food industries as a rapid, simple and inexpensive measuring method.</jats:p></jats:sec>

Akriti Srivastava, Manjeet Harijan, Rajniti Prasad et al.

Journal of Molecular Recognition • 2024

<jats:title>Abstract</jats:title><jats:p>Epitope imprinting has shown better prospects to synthesize synthetic receptors for proteins. Here, dual epitope imprinted polymer electrode (DEIP) matrix was fabricated on gold surface of electrochemical quartz crystal microbalance (EQCM) for recognition of target epitope sequence in blood samples of patients suffering from brain fever. Epitope sequences from outer membrane protein Por B of <jats:italic>Neisseria meningitidis</jats:italic> (MC58) bacteria predicted through immunoinformatic tools were chosen for imprinting. Self‐assembled monolayers (SAM) of cysteine appended epitope sequences on gold nanoparticles were subjected to polymerization prior to electrodeposition on gold coated EQCM electrode. The polymeric matrix was woven around the cysteine appended epitope SAMs through multiple monomers (3‐sulfo propyl methacrylate potassium salt (3‐SPMAP), benzyl methacrylate (BMA)) and crosslinker (N, N′‐methylene‐<jats:italic>bis</jats:italic>‐acrylamide). On extraction of the peptide sequences, imprinted cavities were able to selectively and specifically bind targeted epitope sequences in laboratory samples as well as ‘real’ samples of patients. Selectivity of sensor was examined through mismatched peptide sequences and certain plasma proteins also. The sensor was able to show specific binding towards the blood samples of infected patients, even in the presence of ‘matrix’ and other plasma proteins such as albumin and globulin. Even other peptide sequences, similar to epitope sequences only with one or two amino acid mismatches were also unable to show any binding. The analytical performance of DEIP‐EQCM sensor was tested through selectivity, specificity, matrix effect, detection limit (0.68–1.01 nM), quantification limit (2.05–3.05 nM) and reproducibility (RSD ~ 5%). Hence, a diagnostic tool for bacterium causing meningitis is successfully fabricated in a facile manner which will broaden the clinical access and make efficient population screening feasible.</jats:p>

C. A. Corcoran, R. K. Kobos

Biotechnology and Bioengineering • 1987

<jats:title>Abstract</jats:title><jats:p>The feasibility of using specific enzyme and transport inhibitors to minimize the glutamine response of a potentiometric microbial sensor is demonstrated. The glutamine response of a bacterial electrode prepared with <jats:italic>Escherichia coli</jats:italic> as the biocatalyst in conjunction with an ammonia gas‐sensing electrode was greatly reduced by treating the electrode with the enzyme inhibitor 6‐diazo‐5‐oxo‐<jats:sc>L</jats:sc>‐norleucine (DONL) and the transport inhibitor γ‐<jats:sc>L</jats:sc>‐glutamylhydrazide. Each inhibitor effectively decreased glutamine response to a level sufficiently low to be considered negligible in clinical studies. Although the sensor ultimately recovered from the effects of a single exposure to an inhibitor, continuous exposure at an optimum concentration maintained a low response to glutamine. Furthermore, the treatment of the sensor with both inhibitors simultaneously resulted in a negligible response to glutamine of &lt;1 mV, indicating that both inhibitors are necessary for optimum inhibition of glutamine response. This approach is promising as a means of enhancing the selectivity of microbial sensors.</jats:p>

Maria del Carmen Jaramillo, Eduard Torrents, Rodrigo Martínez‐Duarte et al.

ELECTROPHORESIS • 2010

<jats:title>Abstract</jats:title><jats:p>Dielectrophoresis (DEP) represents a powerful approach to manipulate and study living cells. Hitherto, several approaches have used 2‐D DEP chips. With the aim to increase sample volume, in this study we used a 3‐D carbon‐electrode DEP chip to trap and release bacterial cells. A continuous flow was used to plug an <jats:italic>Escherichia coli</jats:italic> cell suspension first, to retain cells by positive DEP, and thereafter to recover them by washing with peptone water washing solution. This approach allows one not only to analyze DEP behavior of living cells within the chip, but also to further recover fractions containing DEP‐trapped cells. Bacterial concentration and flow rate appeared as critical parameters influencing the separation capacity of the chip. Evidence is presented demonstrating that the setup developed in this study can be used to separate different types of bacterial cells.</jats:p>

Sun Ja Kim, T. H. Chung, S. H. Bae et al.

Applied Physics Letters • 2009

<jats:p>Bacterial inactivation experiment was performed using atmospheric pressure microplasma jets driven by radio-frequency wave of 13.56 MHz and by low frequency wave of several kilohertz. With addition of a ground ring electrode, the discharge current, the optical emission intensities from reactive radicals, and the sterilization efficiency were enhanced significantly. When oxygen gas was added to helium at the flow rate of 5 SCCM, the sterilization efficiency was enhanced. From the survival curve of Escherichia coli, the primary role in the inactivation was played by reactive species with minor aid from heat, UV photons, charged particles, and electric fields.</jats:p>

Rong Liu, Lina Ma, Shu Huang et al.

New Journal of Chemistry • 0

<p>A polyaniline (PANI)/graphene (GN)/bacterial cellulose (BC) flexible and freestanding supercapacitor electrode is synthesized <italic>via</italic> a facile chemical polymerization and filtering method.</p>

G. A. Rechnitz, T. L. Riechel, R. K. Kobos et al.

Science • 1978

<jats:p> A novel bioselective membrane electrode for L-glutamine has been constructed by coupling living bacteria of the strain <jats:italic>Sarcina flava</jats:italic> to a potentiometric ammonia gas sensor. Tests in aqueous standards and human serum show that the electrode combines excellent sensitivity and selectivity with rapid response and a useful lifetime of at least 2 weeks. </jats:p>

Kô Takehara, Shinya Nakashima, Shinya Yamasaki et al.

Chemistry Letters • 2007

<jats:title>Abstract</jats:title> <jats:p>Bioluminescence reaction by bacterial luciferase has been successfully controlled by a controlled-potential electrolysis using platinum-mesh electrode to regenerate the reduced form of flavin mononucleotide (FMNH2), which is one of the substrates of the reaction. It was found that the regeneration of FMNH2 is facilitated by the adsorbed hydrogen atoms formed on a platinum electrode surface in the presence of phosphate ions.</jats:p>

L. Jourdin, S. Freguia, V. Flexer et al.

Environmental Science &amp; Technology • 2016

The enhancement of microbial electrosynthesis (MES) of acetate from CO2 to performance levels that could potentially support practical implementations of the technology must go through the optimization of key design and operating conditions. We report that higher proton availability drastically increases the acetate production rate, with pH 5.2 found to be optimal, which will likely suppress methanogenic activity without inhibitor addition. Applied cathode potential as low as -1.1 V versus SHE still achieved 99% of electron recovery in the form of acetate at a current density of around -200 A m(-2). These current densities are leading to an exceptional acetate production rate of up to 1330 g m(-2) day(-1) at pH 6.7. Using highly open macroporous reticulated vitreous carbon electrodes with macropore sizes of about 0.6 mm in diameter was found to be optimal for achieving a good balance between total surface area available for biofilm formation and effective mass transfer between the bulk liquid and the electrode and biofilm surface. Furthermore, we also successfully demonstrated the use of a synthetic biogas mixture as carbon dioxide source, yielding similarly high MES performance as pure CO2. This would allow this process to be used effectively for both biogas quality improvement and conversion of the available CO2 to acetate.

A. Mulchandani, P. Mulchandani, I. Kaneva et al.

Analytical Chemistry • 1998

A potentiometric microbial biosensor for the direct measurement of organophosphate (OP) nerve agents was developed by modifying a pH electrode with an immobilized layer of Escherichia coli cells expressing organophosphorus hydrolase (OPH) on the cell surface. OPH catalyzes the hydrolysis of organophosporus pesticides to release protons, the concentration of which is proportional to the amount of hydrolyzed substrate. The sensor signal and response time were optimized with respect to the buffer pH, ionic concentration of buffer, temperature, and weight of cells immobilized using paraoxon as substrate. The best sensitivity and response time were obtained using a sensor constructed with 2.5 mg of cells and operating in pH 8.5, 1 mM HEPES buffer. Using these conditions, the biosensor was used to measure as low as 2 microM of paraoxon, methyl parathion, and diazinon. The biosensor had very good storage and multiple use stability. The use of cells with the metabolic enzyme expressed on cell surface as a biological transducer provides advantages of no resistances to mass transport of the analyte and product across the cell membrane and low cost due to elimination of enzyme purification, over the conventional microbial biosensors based on cells expressing enzyme intracellularly and enzyme-based sensors, respectively.

Yonggang Yang, Lei Yan, Jianhua Song et al.

RSC Advances • 2018

Sediment microbial fuel cells (SMFCs) is a promising technology for bioremediation, environmental monitoring and remote power supply in various water environments. Optimizing the anode/cathode surface area ratio (SARa/c) is important to enhance the power and decrease the cost of SMFCs. However, in fact, little information has been reported to optimize the SARa/c of SMFCs in individual or stacked mode. This study comparatively analyzed the effects of electrode surface areas on the performance of single SMFCs and serial SMFC-stacks under separated- and connected-hydraulic conditions. The results suggested an optimal SARa/c of 1 to 1.33 for both single and serial stacked SMFCs. Voltage reversal occurred in serial SMFC stacks with unoptimal SARa/c but not in optimized stacks. The more the SARa/c deviated from the optimal SARa/c, the more easily the voltage reversal occurred (i.e. lower reversal current). Compared to a separated-hydraulic environment, a connected-hydraulic environment showed no effect on the power generation of anode-limiting SMFC stacks but decreased the power generation and reversal current of cathode-limiting SMFCs, probably due to larger parasitic current. The results are important for the scale-up and application of SMFCs.

H. Ukeda, G. Wagner, U. Bilitewski et al.

Journal of Agricultural and Food Chemistry • 1992

A flow injection analysis system for the determination of short-chain fatty acids was developed incorporating a microbial electrode based on an oxygen electrode and Arthrobacter nicotiana immobilized behind a dialysis membrane. The system showed a high selectivity for short-chain fatty acids (C 4:0 -C 12:0 ), and the system response was linearly related to the concentration of butyric acid over the range 0.11-1.7 mM. The sampling freguency was approximately 20 samples/h at a carrier flow rate of 1.0 mL/min

M. T. Noori, G. Bhowmick, B. R. Tiwari et al.

Environmental Technology • 2018

ABSTRACT Waste generation from healthcare facilities now has become a concerning issue as it contain plastic and metals. Medicine wrappers are one of the major portions of healthcare solid waste, which impel intensive solid waste management practice due to fewer possibilities of deriving by-products. However, it can be recycled and used as an electrode material in microbial fuel cells (MFCs). An electrode material for application in MFCs is a crucial component, which governs total fabrication cost as well as power recovery, thus a cost-effective, stable and durable electrode is essential. In this endeavour, a new metallic (aluminium) waste material, a waste medicine wrapper (WMW), was evaluated for feasibility to be used as anode/cathode in MFCs. Based on the stability test under corrosive environment (1 N KCl), the WMW electrode sustained a maximum current of 46 mA during cyclic voltammetry (CV) and noted only 14% reduction in current at an applied voltage of +0.4 V after 2500 s in chronoamperometry, indicating its good stability. Power recovery from MFC using WMW was higher than the MFC using bare carbon felt as an anode (27 vs. 21 mW/m2). The entire analytical test results viz. CV, electrochemical impedance spectroscopy and power performance established WMW as an excellent anode rather than cathode material. GRAPHICAL ABSTRACT

Hao Zhu, Zhiwei Dong, Qiong Huang et al.

RSC Advances • 2019

Microbial electrosynthesis (MES) allows the transformation of CO2 into value-added products by coupling with renewable energy. The enhancement in the microbial activity and electron transfer rate via a new electrode modification method is essential for developing MES. Here, three groups of granular activated carbon decorated by Fe3O4 (Fe3O4/GAC) with mass fractions of 23%, 38% and 50% were prepared and compared with bare GAC. The volumetric acetate production rate of MES with Fe3O4/GAC-38% was the highest (0.171 g L−1 d−1), which was 1.4 times higher that of the control (bare GAC), and the final acetate concentration reached 5.14 g L−1 within 30 days. Linear sweep voltammetry and microbial community analyses suggested that Fe3O4/GAC facilitates extracellular electron transfer and improves the enrichment of electrochemically active bacteria. Fe3O4/GAC is an effective three-dimensional electrode material that enhances biofilm activity on GAC and improves MES efficiency.

T. Yamashita, Hiroshi Yokoyama

Biotechnology for Biofuels • 2018

BackgroundMetals are considered a suitable anode material for microbial fuel cells (MFCs) because of their high electrical conductivity. However, only a few types of metals have been used as anodes, and an extensive screening of metals has not yet been conducted. In this study, to develop a new metal anode for increased electricity generation in MFCs, 14 different metals (Al, Ti, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Ag, In, Sn, Ta, and W) and 31 of their oxidized forms were comprehensively tested. Oxidized-metal anodes were prepared using flame oxidation, heat treatment, and electrochemical oxidation. The selected anodes were further evaluated in detail using air–cathode single-chambered MFCs.ResultsThe untreated Mo and electrochemically oxidized Mo anodes showed high averages of maximum power densities in the screening test, followed by flame-oxidized (FO) W, FO-Fe, FO-Mo, and Sn-based anodes. The untreated Mo and FO-W anodes were selected for further evaluation. X-ray analyses revealed that the surface of the Mo anode was naturally oxidized in the presence of air, forming a layer of MoO3, a known oxidation catalyst. A high maximum power density (1296 mW/m2) was achieved using the Mo anode in the MFCs, which was superior to that obtained using the FO-W anode (1036 mW/m2). The Mo anode, but not the FO-W anode, continued to produce current without detectable corrosion until the end of operation (350 days). Geobacter was abundant in both biofilms on the Mo and FO-W anodes, as analyzed by high-throughput sequencing of the 16S rRNA gene.ConclusionsThe screening test revealed that Mo, W, Fe, and Sn are useful MFC anode materials. The detailed analyses demonstrated that the Mo anode is a high-performance electrode with structural simplicity and long-term stability in MFCs. The anode can be easily prepared by merely shaping Mo materials to the desired forms. These properties would enable the large-scale preparation of the anode, required for practical MFC applications. This study also implies the potential involvement of Geobacter in the Mo and W cycles on Earth.

Lola Gonzalez Olias, P. Cameron, M. di Lorenzo

Frontiers in Energy Research • 2019

The growing use of herbicides in agriculture poses increasing concerns on the pollution of water systems worldwide. To be able to assess the presence of these compounds in waters and limit their impact on human health and ecosystems, the development of effective in-situ monitoring tools is key. Yet, many existing sensing technologies are not suitable for in-situ and remote applications, due to challenges in portability, durability, cost and power requirements. In this study, we explore for the first time the use of an algal-assisted cathode in a photosynthetic microbial fuel cell (p-MFC) as a self-powered dissolved oxygen probe for herbicides detection in water. The cathode is enriched with the alga Scenedesmus obliquus and two different electrode materials are tested, graphite felt and indium tin oxide, which mainly differ in porosity, surface roughness and transparency. Despite the much larger specific surface area of graphite felt compared to indium tin oxide, the current generated under light was only 10 times larger (109 ± 2µA vs. 10.5 ± 0.6 µA) and 8 times larger in the dark (37 ± 5 µA vs. 4.2 ± 0.6 µA). By generating a current output that correlates with the dissolved oxygen in the catholyte, the resulting p-MFCs could detect the EU legal atrazine concentration limit of 0.1 µg L-1. The use of graphite felt led to shorter response times and better sensitivity, as a result of the greater current baseline. In both cases, the current baseline was recovered after exposure of the sensor to frequent toxic events, thus showing the resilience of the cathodic biofilm and the potential of the p-MFCs for early warnings of herbicides pollution in water.

B. Logan, Emily Zikmund, Wulin Yang et al.

Environmental Science &amp; Technology • 2018

Low solution conductivity is known to adversely impact power generation in microbial fuel cells (MFCs), but its impact on measured electrode potentials has often been neglected in the reporting of electrode potentials. While errors in the working electrode (typically the anode) are usually small, larger errors can result in reported counter electrode potentials (typically the cathode) due to large distances between the reference and working electrodes or the use of whole cell voltages to calculate counter electrode potentials. As shown here, inaccurate electrode potentials impact conclusions concerning factors limiting power production in MFCs at higher current densities. To demonstrate how the electrochemical measurements should be adjusted using the solution conductivity, electrode potentials were estimated in MFCs with brush anodes placed close to the cathode (1 cm) or with flat felt anodes placed further from the cathode (3 cm) to avoid oxygen crossover to the anodes. The errors in the cathode potential for MFCs with brush anodes reached 94 mV using acetate in a 50 mM phosphate buffer solution. With a felt anode and acetate, cathode potential errors increased to 394 mV. While brush anode MFCs produced much higher power densities than flat anode MFCs under these conditions, this better performance was shown primarily to result from electrode spacing following correction of electrode potentials. Brush anode potentials corrected for solution conductivity were the same for brushes set 1 or 3 cm from the cathode, although the range of current produced was different due to ohmic losses with the larger distance. These results demonstrate the critical importance of using corrected electrode potentials to understand factors limiting power production in MFCs.

Mohita Sharma, Y. Alvarez-Gallego, W. Achouak et al.

Journal of Materials Chemistry A • 2019

(a) Pictograph and (b) schematic representation of the placement of multiple working electrodes with a single counter electrode and reference electrode using an N'Stat setup and (c) the schematic of the potentiostat interface connection with the electrochemical cell.

R. Rossi, B. Cario, C. Santoro et al.

Environmental Science &amp; Technology • 2019

Direct comparisons of microbial fuel cells based on maximum power densities are hindered by different reactor and electrode sizes, solution conductivities, and materials. We propose an alternative method here, the electrode potential slope (EPS) analysis, to enable quantitative comparisons based on anode and cathode area-based resistances and operating potentials. Using EPS analysis, the brush anode resistance ( RAn = 10.6 ± 0.5 mΩ m2) was shown to be 28% lower than the resistance of a 70% porosity diffusion layer (70% DL) cathode ( RCat = 14.8 ± 0.9 mΩ m2) and 24% lower than the solution resistance ( RΩ = 14 mΩ m2) (acetate in a 50 mM phosphate buffer solution). Using a less porous cathode (30% DL) did not impact the cathode resistance but did reduce the cathode performance due to a lower operating potential. With low-conductivity domestic wastewater ( RΩ = 87 mΩ m2), both electrodes had higher resistances [ RAn = 75 ± 9 mΩ m2, and RCat = 54 ± 7 mΩ m2 (70% DL)]. Our analysis of the literature using EPS analysis shows how electrode resistances can easily be quantified to compare system performance when the electrode distances are changed or the sizes of the electrodes are different.