Qianjin Chen, Kim McKelvey, M. Edwards et al.

The Journal of Physical Chemistry C • 2016

Ion transport near interfaces is a fundamental phenomenon of importance in electrochemical, biological, and colloidal systems. In particular, electric double layers in highly confined spaces have implications for ion transport in nanoporous energy storage materials. By exploiting redox cycling amplification in lithographically fabricated thin-layer electrochemical cells comprising two platinum electrodes separated by a distance of 150–450 nm, we observed current enhancement during cyclic voltammetry of the hexaamineruthenium(III) chloride redox couple (Ru(NH3)63/2+) at low supporting electrolyte concentrations, resulting from ion enrichment of Ru(NH3)63/2+ in the electrical double layers and an enhanced ion migration contribution to mass transport. The steady-state redox cycling was shown to decrease to predominately diffusion controlled level with increasing supporting electrolyte concentration. Through independent biasing of the potential on the individual Pt electrodes, the voltammetric transport limit...

M. Abarkan, A. Pirog, Donnie Mafilaza et al.

Advanced Science • 2022

Electrical signals are fundamental to key biological events such as brain activity, heartbeat, or vital hormone secretion. Their capture and analysis provide insight into cell or organ physiology and a number of bioelectronic medical devices aim to improve signal acquisition. Organic electrochemical transistors (OECT) have proven their capacity to capture neuronal and cardiac signals with high fidelity and amplification. Vertical PEDOT:PSS‐based OECTs (vOECTs) further enhance signal amplification and device density but have not been characterized in biological applications. An electronic board with individually tuneable transistor biases overcomes fabrication induced heterogeneity in device metrics and allows quantitative biological experiments. Careful exploration of vOECT electric parameters defines voltage biases compatible with reliable transistor function in biological experiments and provides useful maximal transconductance values without influencing cellular signal generation or propagation. This permits successful application in monitoring micro‐organs of prime importance in diabetes, the endocrine pancreatic islets, which are known for their far smaller signal amplitudes as compared to neurons or heart cells. Moreover, vOECTs capture their single‐cell action potentials and multicellular slow potentials reflecting micro‐organ organizations as well as their modulation by the physiological stimulator glucose. This opens the possibility to use OECTs in new biomedical fields well beyond their classical applications.

Chia-Fei Liu, Tzu-Hsin Lee, Jeng-fen Liu et al.

Scientific Reports • 2018

Ti-24Nb-4Zr-8Sn (Ti2448), a new β-type Ti alloy, consists of nontoxic elements and exhibits a low uniaxial tensile elastic modulus of approximately 45 GPa for biomedical implant applications. Nevertheless, the bio-corrosion resistance and biocompatibility of Ti2448 alloys must be improved for long-term clinical use. In this study, a rapid electrochemical anodization treatment was used on Ti2448 alloys to enhance the bio-corrosion resistance and bone cell responses by altering the surface characteristics. The proposed anodization process produces a unique hybrid oxide layer (thickness 50–120 nm) comprising a mesoporous outer section and a dense inner section. Experiment results show that the dense inner section enhances the bio-corrosion resistance. Moreover, the mesoporous surface topography, which is on a similar scale as various biological species, improves the wettability, protein adsorption, focal adhesion complex formation and bone cell differentiation. Outside-in signals can be triggered through the interaction of integrins with the mesoporous topography to form the focal adhesion complex and to further induce osteogenic differentiation pathway. These results demonstrate that the proposed electrochemical anodization process for Ti2448 alloys with a low uniaxial tensile elastic modulus has the potential for biomedical implant applications.

P. Ash, H. Reeve, J. Quinson et al.

Analytical Chemistry • 2016

We describe a method for addressing redox enzymes adsorbed on a carbon electrode using synchrotron infrared microspectroscopy combined with protein film electrochemistry. Redox enzymes have high turnover frequencies, typically 10–1000 s–1, and therefore, fast experimental triggers are needed in order to study subturnover kinetics and identify the involvement of transient species important to their catalytic mechanism. In an electrochemical experiment, this equates to the use of microelectrodes to lower the electrochemical cell constant and enable changes in potential to be applied very rapidly. We use a biological cofactor, flavin mononucleotide, to demonstrate the power of synchrotron infrared microspectroscopy relative to conventional infrared methods and show that vibrational spectra with good signal-to-noise ratios can be collected for adsorbed species with low surface coverages on microelectrodes with a geometric area of 25 × 25 μm2. We then demonstrate the applicability of synchrotron infrared microspectroscopy to adsorbed proteins by reporting potential-induced changes in the flavin mononucleotide active site of a flavoenzyme. The method we describe will allow time-resolved spectroscopic studies of chemical and structural changes at redox sites within a variety of proteins under precise electrochemical control.

B. Esteban‐Fernandez de Avila, E. Araque, S. Campuzano et al.

Analytical Chemistry • 2015

Novel disposable electrochemical DNA sensors were prepared for the detection of a target DNA sequence on the p53 tumor suppressor (TP53) gene. The electrochemical platform consisted of screen-printed carbon electrodes (SPCEs) functionalized with a water-soluble reduced graphene oxide-carboxymethylcellulose (rGO-CMC) hybrid nanomaterial. Two different configurations involving hairpin specific capture probes of different length covalently immobilized through carbodiimide chemistry on the surface of rGO-CMC-modified SPCEs were implemented and compared. Upon hybridization, a streptavidin-peroxidase (Strep-HRP) conjugate was employed as an electrochemical indicator. Hybridization was monitored by recording the amperometric responses measured at -0.10 V (vs an Ag pseudo-reference electrode) upon the addition of 3,3',5,5'-tetramethylbenzidine (TMB) as a redox mediator and H2O2 as an enzyme substrate. The implemented DNA platforms allow single nucleotide polymorphism (SNP) discrimination in cDNAs from human breast cancer cell lines, which makes such platforms excellent as new diagnosis tools in clinical analysis.

Hye Kyu Choi, Jin-Ha Choi, Jinho Yoon

Biosensors • 2023

Neurotransmitters are chemical compounds released by nerve cells, including neurons, astrocytes, and oligodendrocytes, that play an essential role in the transmission of signals in living organisms, particularly in the central nervous system, and they also perform roles in realizing the function and maintaining the state of each organ in the body. The dysregulation of neurotransmitters can cause neurological disorders. This highlights the significance of precise neurotransmitter monitoring to allow early diagnosis and treatment. This review provides a complete multidisciplinary examination of electrochemical biosensors integrating nanomaterials and nanotechnologies in order to achieve the accurate detection and monitoring of neurotransmitters. We introduce extensively researched neurotransmitters and their respective functions in biological beings. Subsequently, electrochemical biosensors are classified based on methodologies employed for direct detection, encompassing the recently documented cell-based electrochemical monitoring systems. These methods involve the detection of neurotransmitters in neuronal cells in vitro, the identification of neurotransmitters emitted by stem cells, and the in vivo monitoring of neurotransmitters. The incorporation of nanomaterials and nanotechnologies into electrochemical biosensors has the potential to assist in the timely detection and management of neurological disorders. This study provides significant insights for researchers and clinicians regarding precise neurotransmitter monitoring and its implications regarding numerous biological applications.

Jingjing Zhang, Junyu Zhou, Rongrong Pan et al.

ACS Sensors • 2018

Previous measurements of cell populations might obscure many important cellular differences, and new strategies for single-cell analyses are urgently needed to re-examine these fundamental biological principles for better diagnosis and treatment of diseases. Electrochemistry is a robust technique for the analysis of single living cells that has the advantages of minor interruption of cellular activity and provides the capability of high spatiotemporal resolution. The achievements of the past 30 years have revealed significant information about the exocytotic events of single cells to elucidate the mechanisms of cellular activity. Currently, the rapid developments of micro/nanofabrication and optoelectronic technologies drive the development of multifunctional electrodes and novel electrochemical approaches with higher resolution for single cells. In this Perspective, three new frontiers in this field, namely, electrochemical microscopy, intracellular analysis, and single-cell analysis in a biological system (i.e., neocortex and retina), are reviewed. The unique features and remaining challenges of these techniques are discussed.

Lizhen Chen, Ying Fu, Naixiang Wang et al.

ACS Applied Materials & Interfaces • 2018

Cell surface glycans play critical roles in diverse biological processes, such as cell-cell communication, immunity, infection, development, and differentiation. Their expressions are closely related to cancer growth and metastasis. This work demonstrates an organic electrochemical transistor (OECT)-based biosensor for the detection of glycan expression on living cancer cells. Herein, mannose on human breast cancer cells (MCF-7) as the target glycan model, poly dimethyl diallyl ammonium chloride-multiwall carbon nanotubes (PDDA-MWCNTs) as the loading interface, concanavalin A (Con A) with active mannose binding sites, aptamer and horseradish peroxidase co-immobilized gold nanoparticles (HRP-aptamer-Au NPs) as specific nanoprobes are used to fabricate the OECT biosensor. In this strategy, PDDA-MWCNT interfaces can enhance the loading of Con A, and the target cells can be captured through Con A via active mannose binding sites. Thus, the expression of cell surface can be reflected by the amount of cells captured on the gate. Specific nanoprobes are introduced to the captured cells to produce an OECT signal because of the reduction of hydrogen peroxide catalyzed by HRP conjugated on Au nanoparticles, while the aptamer on nanoprobes can selectively recognize the MCF-7 cells. It is reasonable that more target cells are captured on the gate electrode, more HRP-nanoprobes are loaded thus a larger signal response. The device shows an obvious response to MCF-7 cells down to 10 cells/μL and can be used to selectively monitor the change of mannose expression on cell surfaces upon a treatment with the N-glycan inhibitor. The OECT-based biosensor is promising for the analysis of glycan expressions on the surfaces of different types of cells.

Yi-Fan Ruan, Hai‐Yan Wang, Xiao-Mei Shi et al.

Analytical Chemistry • 2020

Engineered nanopipette tools have recently emerged as a powerful approach for electrochemical nanosensing, which has major implications in both fundamental biological research and biomedical applications. Herein, we describe a generic method of target-triggered assembly of aptamers in a nanopipette for nanosensing, which is exemplified by sensitive and rapid electrochemical single-cell analysis of adenosine triphosphate (ATP), a ubiquitous energy source in life and important signaling molecules in many physiological processes. Specifically, a layer of thiolated aptamers is immobilized onto a Au-coated interior wall of a nanopipette tip. With backfilled pairing aptamers, the engineered nanopipette is then used for probing intracellular ATP via the ATP-dependent linkage of the split aptamers. Due to the higher surface charge density from the aptamer assembly, the nanosensor would exhibit an enhanced rectification signal. Besides, this ATP-responsive nanopipette tool possesses excellent selectivity and stability as well as high recyclability. This work provides a practical single-cell nanosensor capable of intracellular ATP analysis. More generally, integrated with other split recognition elements, the proposed mechanism could serve as a viable basis for addressing many other important biological species.

Liming Bai, Cristina García Elósegui, Weiqi Li et al.

Frontiers in Chemistry • 2019

Organic electrochemical transistors (OECTs) are recently developed high-efficient transducers not only for electrochemical biosensor but also for cell electrophysiological recording due to the separation of gate electrode from the transistor device. The efficient integration of OECTs with electrochemical gate electrode makes the as-prepared sensors with improved performance, such as sensitivity, limit of detection, and selectivity. We herein reviewed the recent progress of OECTs-based biosensors and cell electrophysiology recording, mainly focusing on the principle and chemical design of gate electrode and the channel. First, the configuration, work principle, semiconductor of OECT are briefly introduced. Then different kinds of sensing modes are reviewed, especially for the biosensing and electrophysiological recording. Finally, the challenges and opportunities of this research field are discussed.

Xiao Su, T. A. Hatton

Physical Chemistry Chemical Physics • 2017

Adsorption at charged interfaces plays an important role across all aspects of physical chemistry, from biological interactions within living organisms to chemical processes such as catalysis and separations. With recent advances in materials chemistry, there are a host of modified electrodes being investigated for electrosorption, especially in separations science. In this perspective, we provide an overview of functional interfaces being used for electrosorption, ranging from electrochemical separations such as deionization and selective product recovery to biological applications. We cover the various molecular mechanisms which can be used to enhance ion capacity, and in some cases, provide selectivity; as well as discuss the parasitic Faradaic reactions which often impair electrosorption performance. Finally, we point to the importance of electrochemical configurations, in particular the advantages of asymmetric cell design, and highlight the opportunities for selective electrosorption brought about by redox-mediated systems.

N. Askari, Dr. Mohammadreza Askari, A. Di Bartolomeo

Journal of The Electrochemical Society • 2022

A multi-component nanocomposite consisting of manganese oxide (Mn3O4), cobalt oxide (Co3O4), and reduced graphene oxide (rGO) in the form of Mn3O4-Co3O4-rGO was synthesized by the hydrothermal method. Cyclic voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry analyses were performed to investigate the synergistic effect of metal oxides on the surface of rGO nano-sheets in the methanol oxidation reaction and ethanol oxidation reaction process. The good electrochemical results show that Mn3O4-Co3O4-rGO can be a promising, inexpensive nano-catalyst for application in alcohol fuel cells. In addition, as nanoparticles inhibit cancer cells growth by producing reactive oxygen species (ROS), we explored the synergic effect of the three-component synthetic nanomaterial in gastric cancer cells (AGS). Results indicated that Mn3O4-Co3O4-rGO inhibited AGS cell growth by induction of ROS, upregulation of Mir-20a-5p, and downregulation of ZBTB4 gene. This might provide a novel molecular-targeted strategy of microRNA-based therapeutics for gastric cancer treatment.

Meiling Lian, Y. Shi, Liuxing Chen et al.

ACS Sensors • 2022

The inactive adsorption and interference of biomolecules in electrochemical biosensors is a topic of intense interest. Directly utilizing native cell membranes to endow electrochemical surfaces with antifouling and biocompatible features is a promising strategy, rather than attempting to synthetically replicate complex biological interface properties. In this study, we present a facial and sensitive sandwich-type antifouling immunoassay through platelet membrane/Au nanoparticle/delaminated V2C nanosheet (PM/AuNPs/d-V2C)-modified electrode as the substrate of sensing interface and methylene blue/aminated metal organic framework (MB@NH2-Fe-MOF-Zn) as an electrochemical signal probe. The biosensor perfectly integrates the high conductivity of AuNPs-loaded V2C MXene with the excellent loading property of NH2-Fe-MOF-Zn to improve the electrochemical sensing performance. In addition, the excellent antifouling properties of the homogeneous cell membrane can effectively prevent the non-specific adsorption of model proteins. The obtained antifouling biosensor possesses the capability of ultrasensitive detection of CD44 and CD44-positive cancer cell in complex liquids and exhibits good analytical performance for the analysis of CD44 with a linear range from 0.5 ng/mL to 500 ng/mL. This strategy of developing cell membrane-based biosensing systems with enhanced antifouling capability can be easily expanded to the construction of other complex biosensors, and the advanced biological probes and analytical methods provide a favorable means to accurately quantify biomarkers associated with tumor progression.

Enas M. Abou-Taleb, M. Hellal, Kholod H. Kamal

Water and Environment Journal • 2020

This work investigated the removal of phenol from petroleum wastewater by the electro‐oxidation process. The experimental design was developed on a pilot‐scale electro‐oxidation system equipped with a cylindrical shape of graphite electrodes as an anode and stainless‐steel electrodes as a cathode. An initial study was performed based on operating variables such as current density and time on real petroleum wastewater. The optimum conditions were obtained as a current density of 3 mA/cm2 and time 15 min. Under these applied optimum conditions, complete phenol removal from an initial concentration of about 6.8 mg/L was achieved. Also, 50–60% removal of organic matter in terms of chemical oxygen demand (COD) and biological oxygen demand (BOD). The removal of organic matter using electro‐oxidation requires a long reaction time. Also, the economic study indicated that the energy consumption was determined to be 0.79 kWh/m3 and the operating cost was 0.051 $/m3 which is very economical compared with conventional methods.

Jing Li, Cailing Zhu, Wenjing Peng et al.

Analytical Chemistry • 2023

Hydrogen sulfide (H2S), as the third gas transporter in biological systems, plays a key role in the regulation of biological cells. Real-time detection of local H2S concentration in vivo is an important and challenging task. Herein, we explored a novel and facile strategy to develop a flexible and transparent H2S sensor based on gold nanowire (AuNW) and carbon nanotube (CNT) films embedded in poly(dimethylsiloxane) (PDMS) (AuNWs/CNTs/PDMS). Taking the advantage of the sandwich-like nanostructured network of AuNWs/CNTs, the prepared electrochemical sensing platform exhibited desirable electrocatalytic activity toward H2S oxidation with a wide linear range (5 nM to 24.9 μM) and a low dete ction limit (3 nM). Furthermore, thanks to the good biocompatibility and flexibility of the sensor, HeLa cells can be cultured directly on the electrode, allowing real-time monitoring of H2S released from cells under a stretched state. This work provides a versatile strategy for the construction of stretchable electrochemical sensors, which has potential applications in the study of H2S-related signal mechanotransduction and pathological processes.

Nianzu Liu, Jingyao Song, Yanwei Lu et al.

Analytical Chemistry • 2019

The rapid, convenient, and selective assaying of clinical targets directly in complex biological media brings with it the potential to revolutionize diagnostics. One major hurdle to impact is retention of selectivity and a tight control of nonspecific surface interactions or biofouling. We report herein, the construction of an antifouling interface through the covalent attachment of designed branched zwitterionic peptides onto electrodeposited polyaniline film. The antifouling capability of the designed branched peptide significantly outperforms that of the commonly used PEG and linear peptides. The interfaces modified with branched peptides are exceptionally effective in reducing a nonspecific protein and cell adsorption, as verified by electrochemical and fluorescent characterization. The derived sensors with mucin1 protein (MUC1) aptamer as the recognition element detect MUC1-positive MCF-7 breast cancer cells in human serum with high sensitivity and selectivity. The linear response range of the cytosensor for the MCF-7 cell is from 50 to 106 cells/mL, with a limit of detection as low as 20 cells/mL. More importantly, the assaying performances remain unchanged in human serum owing to the presence of branched antifouling peptide, indicating feasibility of the cytosensor for practical cancer cell quantification in complex samples.

Aydin Bordbar-Khiabani, M. Gasik

Scientific Reports • 2023

The performance of current biomedical titanium alloys is limited by inflammatory and severe inflammatory conditions after implantation. In this study, a novel Ti-Nb-Zr-Si (TNZS) alloy was developed and compared with commercially pure titanium, and Ti-6Al-4V alloy. Electrochemical parameters of specimens were monitored during 1 h and 12 h immersion in phosphate buffered saline (PBS) as a normal, PBS/hydrogen peroxide (H 2 O 2 ) as an inflammatory, and PBS/H 2 O 2 /albumin/lactate as a severe inflammatory media. The results showed an effect of the H 2 O 2 in inflammatory condition and the synergistic behavior of H 2 O 2 , albumin, and lactate in severe inflammatory condition towards decreasing the corrosion resistance of titanium biomaterials. Electrochemical tests revealed a superior corrosion resistance of the TNZS in all conditions due to the presence of silicide phases. The developed TNZS was tested for subsequent cell culture investigation to understand its biocompatibility nature. It exhibited favorable cell-materials interactions in vitro compared with Ti-6Al-4V. The results suggest that TNZS alloy might be a competitive biomaterial for orthopedic applications.

D. Özsoylu, T. Wagner, M. Schöning

Current Topics in Medicinal Chemistry • 2022

Electrochemical cell-based biosensors have been showing increasing interest within the last 15 years, with a large number of reports generally dealing with the sensors' sensitivity, selectivity, stability, signal-to-noise ratio, spatiotemporal resolution, etc. However, only a few of them are now available as commercial products on the market. In this review, technological advances, current challenges and opportunities of electrochemical cell-based biosensors are presented. The article encompasses emerging studies, mainly focusing on the last five years (from 2016 to mid 2021), towards cell-based biological field-effect devices, cell-based impedimetric sensors and cell-based microelectrode arrays. In addition, special attention lies on recent progress in recording at the single-cellular level, including intracellular monitoring with high spatiotemporal resolution as well as integration into microfluidics for lab-on-a-chip applications. Moreover, a comprehensive discussion on challenges and future perspectives will address the future potential of electrochemical cell-based biosensors.

Andrei Kulikovsky

Electrochemical Science Advances • 2024

Abstract A model for performance of an axially symmetric pore with the curved generatrix is developed. Oxygen transport along the pore axis and in the radial direction through a thin ionomer film separating the pore volume from the Pt/C surface is taken into account. A performance functional is formulated, and the Euler–Lagrange equation is solved numerically for an optimal pore shape. This shape is close to a cubic paraboloid converging toward the membrane. Polarization curves show superior performance of the optimal pore over the cylindrical pore of the same active (side) surface area. The results suggest the shape of optimal ionomer loading for low‐Pt electrodes.

Christina Martens, Maximilian Quentmeier, Bernhard Schmid et al.

Electrochemical Science Advances • 2025

ABSTRACT Consecutive development of materials, components, and ultimately, devices does not appear to be a promising strategy in CO 2 electroreduction because maintaining comparability and transferring results between idealized and application‐oriented systems proves challenging. A modular cell design and tracking cell conditions via sensors may be a solution. We displayed a strategy to characterize gas diffusion electrode operating regimes in a flow cell with regard to different current density ranges, as well as the impact of the flow gap design. We revealed strong interdependencies between cell components, their functions as well as individual cells when integrated into a stack. Expanding the scope and resolution of experimental data made new information on the change of system parameters in flow cells accessible.

Maurice Friedman, Charles E. McCauley

Transactions of The Electrochemical Society • 1947

The Ruben cell, a new alkaline dry cell, is discussed. This cell comprises the electrochemical system Zn | Zn ( OH ) 2 ( solid ) KOH aq. HgO ( solid ) | Hg and has a rated capacity of 200 milliampere‐hours for each 1.6 gram unit of active material. The open‐circuit voltage of the cell is nominally 1.34 volts and the initial closed‐circuit voltage under normal loads varies from 1.24 to 1.31 v., depending on the load applied. The discharge curves obtained with the Ruben cell on normal drains are substantially flat, thus insuring reasonably uniform voltage output. The utilization of active materials is approximately 80% to 90% and is extremely efficient compared with other types of commercial dry cells. The service obtainable from the Ruben cell under high current drains is approximately 4 to 7 times that of conventional dry cells of equivalent volume when discharged to the usual cutoff potentials of 0.75 to 1.0 volt. Two basic designs are described, one making use of a “roll anode” and the other of a “pressed powder anode” construction. The roll anode cell structure was the first design to go into large scale production, the entire output having been allocated to the Armed Forces during the last war. The pressed powder anode cell, which incorporates such improvements as additional volume reductions for given watt‐hour capacities, may supplant the roll anode cell for commercial applications. These new designs, although still failing to bring the cost of the Ruben cell down to that of conventional dry cells, will offer a distinct advantage when considered from a cost/service ratio. The development of improved production methods will make it commercially competitive, particularly for applications where its small space requirements, long service performance and flat voltage discharge characteristics are important factors.

Eleonora Alfinito, Francesco Milano, Matteo Beccaria et al.

Chemosensors • 2020

The impedance response of an electrochemical cell able to convert sunlight into electrical power is analyzed and discussed. Light conversion is due to a photosynthetic system known as reaction center, which is the core of photosynthesis in several living beings. Under illumination, an abrupt transformation drives the cell electrical response from insulator to conductor and a photocurrent is observed. The impedance spectrum shows a peculiar shape which significantly modifies after the protein activation. It has been analyzed by means of a graphical/analytical/numerical procedure. Some impedance graphical representations are indicated as the most appropriate to suggest the design of an equivalent electrical circuit. Then, the analytical expression of this circuit is formulated and used to set-up a custom Phyton code useful for fitting experimental data. Finally, an appropriate normalization procedure is proposed, which validates data in dark and light and can be useful as a fast screening of measurements.

Eleonora Alfinito, Francesco Milano, Matteo Beccaria et al.

Preprints.org • 2020

Bio-devices are designed to allow biological matter to perform in vitro almost the same functions it performs in vivo. Therefore, they can benefit from the specificities of such materials and are expected to perform better than traditional devices. On the other hand, the integration of biological material with electronic/electrochemical instrumentation requires careful attention and can produce unconventional results. In this paper, we describe the impedance response of an electrochemical cell that converts sunlight into electrical power. It uses the photosynthetic system known as Reaction Center, which is the core of photosynthesis in several living beings. Under illumination, an abrupt transformation drives the cell electrical response from insulator to conductor and a photocurrent is observed. The impedance spectrum shows a peculiar shape which significantly modifies with the protein activation. It has been analyzed by means of a graphical/analytical/ numerical procedure. The modelling identifies an analogue electrical circuit, whose parameters give quantitative information about the underlying process. Finally, an appropriate normalization of data is proposed which validates data in dark and light and can be useful as a fast screening of measurements.

Cameron L. Bentley

Electrochemical Science Advances • 2022

Abstract Scanning electrochemical cell microscopy (SECCM) is a scanning‐droplet‐based technique that allows electrochemical fluxes and/or interfacial reactivity to be measured and visualized with high spatiotemporal resolution. This minireview spotlights the use of SECCM for studying the electrochemistry of (nano)particles, highlighting recent works spanning multiple timescales (i.e., microseconds to seconds) and lengthscales (i.e., nanometers to micrometers) to probe physicochemical phenomena at the sub‐particle, single particle, and/or (micro)ensemble levels. In SECCM, single (nano)particles (or small particle ensembles) are electrochemically interrogated—directly from colloidal solution (i.e., by investigating electrochemical nanoimpacts with a substrate electrode) or supported on an electrochemically inert support electrode—with a pipette probe that is operated in either a stationary (point measurement) or dynamic scanning/imaging mode. Nanoscale‐resolved electrochemical information (e.g., local rates of electron‐ or ion‐transfer, catalytic activity, corrosion resistance, etc.) from SECCM is readily related to (nano)particle structure and properties, collected at a commensurate scale with complementary, co‐located microscopy/spectroscopy techniques, allowing structure and function to be resolved directly and unambiguously down to the sub‐particle level. Understanding structure−function on this scale enables macroscopic “particle‐on‐support” electrode behavior to be rationalized and further predicted, guiding the discovery, design, and engineering of novel electromaterials with enhanced function, which is a “holy grail” in materials science.

Haiheng Xu, Yiqiao Hu, Jinhui Wu

Microbial Cell • 2022

Cancer immunotherapy, which use the own immune system to attack tumors, are increasingly popular treatments. But, due to the tumor immunosuppressive microenvironment, the antigen presentation in the tumor is limited. Recently, a growing number of people use bacteria to stimulate the body’s immunity for tumor treatment due to bacteria themselves have a variety of elements that activate Toll-like receptors. Here, we discuss the use of motility of flagellate bacteria to transport antigens to the tumor periphery to activate peritumoral dendritic cells to enhance the effect of in situ tumor vaccines.

Christoph Mayer

Encyclopedia of Life Sciences • 2012

Abstract Cell wall recycling is a process whereby bacteria degrade their own wall during growth, recover released constituents by active transport and reutilise them either to rebuild the wall or to gain energy. Most knowledge about cell wall recycling comes from studies with the Gram‐negative bacterium Escherichia coli . Within one generation, this organism breaks down and efficiently recycles approximately 60% of the mature peptidoglycan of its side‐wall during cell elongation and approximately 30% of newly deposited septal peptidoglycan during cell division. The reason for the massive turnover of the peptidoglycan is still unclear, although many other bacteria, including Gram‐positives, have been reported to turnover their cell wall and release similar quantities of peptidoglycan fragments during growth and differentiation. Whether these fragments are also recycled is basically unknown. The presence of recycling genes on most bacterial genomes, however, suggests that cell wall recycling is a very common pathway of bacteria. Key Concepts: The peptidoglycan of the bacterial cell wall represents a single, giant, reticular macromolecule (i.e. the murein sacculus) that encases the entire bacterial cell. The peptidoglycan cell wall has to be cleaved continuously during growth to allow cell expansion by insertion of new wall material. Bacteria possess a huge and partially redundant set of cell wall lytic enzymes that potentially target every covalent bond connecting the amino acid and amino sugar building blocks within the peptidoglycan network (cell wall lytic complement). Many bacteria release a great amount of cell wall material during bacterial growth (cell elongation and division). The reason for the massive turnover of approximately 50% of the existing peptidoglycan in one generation is still unclear. Bacteria eventually recover cell wall turnover fragments. The pathways for the continuous recycling of peptidoglycan have been explored in great detail in Escherichia coli . Cell wall recycling in Gram‐positive bacteria has been appreciated just recently and apparently differs from the E. coli paradigm as well as between Gram‐positive species. Cell wall‐derived peptidoglycan fragments function as potent biological effectors. They are involved in sensing the cell wall and growth state, inducing expression of antibiotic resistance genes, and triggering cell differentiation and resuscitation of dormant cells.

Andrei Kulikovsky

Electrochemical Science Advances • 2024

Abstract A model for the transient electrochemical performance of a conical pore in the cathode catalyst layer of a low–Pt PEM fuel cell is developed. The pore is separated from the Pt surface by a thin ionomer film. A transient equation for the oxygen diffusion along the pore coupled to the proton conservation equation in the ionomer film is derived. Numerical solution of the static equations shows superior electrochemical performance of a conical pore as compared to cylindrical pore with equivalent electrochemically active surface area. Equations for the pore impedance are derived by linearization and Fourier–transform of transient equations. The conical pore impedance is calculated and compared to the impedance of equivalent cylindrical pore. It is shown that the pore shape affects the frequency dependence of impedance.

Peter L. Graumann

Cell Motility • 2009

Abstract Bacterial cytoskeletal elements are involved in an astonishing spectrum of cellular functions, from cell shape determination to cell division, plasmid segregation, the positioning of membrane‐associated proteins and membrane structures, and other aspects of bacterial physiology. Interestingly, these functions are not necessarily conserved, neither between different bacterial species nor between bacteria and eukaryotic cells. The flexibility of cytoskeletal elements in performing different tasks is amazing and emphasises their very early development during evolution. This review focuses on the dynamics of cytoskeletal elements from bacteria. Cell Motil. Cytoskeleton 2009. © 2009 Wiley‐Liss, Inc.

Terry J Beveridge

Encyclopedia of Life Sciences • 2001

Abstract Bacterial walls are constructed from a variety of macromolecules and polymers to provide an outer skin around the protoplast, encompassing the cell. In Gram‐positive bacteria, the cell wall consists of peptidoglycan and associated secondary polymers, whereas in Gram‐negative bacteria it consists of an outer membrane and an underlying thin peptidoglycan layer.

Shahid Khan

Cell Motility • 1988

Abstract Bacterial flagella have rotary motors at their base; embedded in the cytoplasmic membrane and powered by transmembrane ion gradients instead of ATP. Assays have been developed to measure the torque output of individual motors over a wide regime of load, to correlate the energizing proton flux with rotation speed and relate through genetic analysis motor structure to function. These assays promise substantial advances in understanding mechanochemical coupling in these motors. Here, I summarize the present status of our understanding of energy transduction in bacterial flagella and compare this with the case for muscle.

Nikola Ojkic, Diana Serbanescu, Shiladitya Banerjee

bioRxiv (Cold Spring Harbor Laboratory) • 2021

Abstract Bacteria have evolved to develop multiple strategies for antibiotic resistance by effectively reducing intra-cellular antibiotic concentrations or antibiotic binding affinities, but the role of cell morphology on antibiotic resistance remains poorly characterized. By analyzing cell morphological data of different bacterial species under antibiotic stress, we find that bacterial cells robustly reduce surface-to-volume ratio in response to most types of antibiotics. Using quantitative modelling we show that by reducing surface-to-volume ratio, bacteria can effectively reduce intracellular antibiotic concentration by decreasing antibiotic influx. The model predicts that bacteria can increase surface-to-volume ratio to promote antibiotic dilution if efflux pump activity is reduced, in agreement with data on membrane-transport inhibitors. Using the particular example of ribosome-targeting antibiotics, we present a systems-level model for the regulation of cell shape under antibiotic stress, and discuss feedback mechanisms that bacteria can harness to increase their fitness in the presence of antibiotics.

Scott Campbell, Andrew Duggleby, Angela Johnson

CORROSION 2011 • 2011

Abstract Mitigation of microbiological related problems, specifically, microbially influenced corrosion (MIC) is often mitigated utilizing biocides or biostatic chemicals. The use of the chemicals is often employed to control viable bacterial numbers, which would ultimately mitigate microbiological activity. However, after applying biocides for over 50 years within the petroleum industry, MIC is present and has been implicated in several critical failures. Although these failures still occur, no work has been done to establish and understand if current treatment regimes are ultimately mitigating MIC by controlling bacteria populations, specifically SRB’s within a biofilm. This paper reports the efficacy of biocides applied in a dynamic flow cell system evaluating current conventional treatment regimes decreasing viable bacterial numbers within a biofilm, and thus decreasing SRB activity. The data suggests that biocides may not be killing bacteria within a biofilm, and after further review of doubling times of SRB’s within the bacterial biofilm, suggests that bacterial cell injury may be a possible explanation rather than bacterial cell kill. Therefore, controlling MIC by applying biocides to simply kill bacteria may not be effective.

Norvell Nelson

Platinum Metals Review • 2002

The destruction of hazardous organic waste produced as waste products in chemical processes has become an industry in itself, regulated by environmental agencies and government bodies. The environmentally harmful waste has been incinerated at high temperature with the aim of forming less harmful and less complex compounds, but this may lead to dioxin formation in the presence of chlorine-containing waste. It may also be treated electrochemically to result in carbon dioxide and water. One on-site electrochemical method, described here, which uses platinum-plated titanium electrodes, can treat most organic waste materials very effectively at low temperatures.

Emma B. Setterington, Evangelyn C. Alocilja

Biosensors • 2012

Biological defense and security applications demand rapid, sensitive detection of bacterial pathogens. This work presents a novel qualitative electrochemical detection technique which is applied to two representative bacterial pathogens, Bacillus cereus (as a surrogate for B. anthracis) and Escherichia coli O157:H7, resulting in detection limits of 40 CFU/mL and 6 CFU/mL, respectively, from pure culture. Cyclic voltammetry is combined with immunomagnetic separation in a rapid method requiring approximately 1 h for presumptive positive/negative results. An immunofunctionalized magnetic/polyaniline core/shell nano-particle (c/sNP) is employed to extract target cells from the sample solution and magnetically position them on a screen-printed carbon electrode (SPCE) sensor. The presence of target cells significantly inhibits current flow between the electrically active c/sNPs and SPCE. This method has the potential to be adapted for a wide variety of target organisms and sample matrices, and to become a fully portable system for routine monitoring or emergency detection of bacterial pathogens.

Shohei Kanamura, Motoshige Yagyu

Journal of The Electrochemical Society • 2023

A method for directly recovering precious metals from polymer electrolyte fuel cells (PEFCs) by electrochemical dissolution without dismantling the cells was developed. After filling a single PEFC containing Pt and Ru catalysts with 1 mol l −1 HCl solution, 100 wt% of Pt and 96 wt% of Ru dissolved into the solution by periodically changing the electric polarity of the fuel and air electrodes containing Pt and Ru metal. To confirm the adaptability of this method to cell stack assemblies (CSAs), electrochemical dissolution tests using 3- and 5-cell CSAs, and a 700 W CSA were also conducted. In the 3- and 5-cell CSA tests, 100 wt% of Pt and 95 wt% of Ru were recovered as ions. In the case of the 700 W CSA, 86.8 wt% of Pt and 88.4 wt% of Ru were recovered as ions in 9.2 L of 1 mol l −1 HCl after 180 min of electrolysis. Power consumption rates for Pt and Ru dissolution in the 700 W CSA cell were approximately 0.13 kW h g −1 . Thus, the feasibility of the electrochemical dissolution method of Pt and Ru from PEFCs without dismantling PEFCs was confirmed.

Felix Wong, Ariel Amir

bioRxiv (Cold Spring Harbor Laboratory) • 2018

Membrane lysis, or rupture, is a cell death pathway in bacteria frequently caused by cell wall-targeting antibiotics. Although several studies have clarified biochemical mechanisms of antibiotic action, a physical understanding of the processes leading to lysis remains lacking. Here, we analyze the dynamics of membrane bulging and lysis in Escherichia coli , where, strikingly, the formation of an initial bulge (“bulging”) after cell wall digestion occurs on a characteristic timescale as fast as 100 ms and the growth of the bulge (“swelling”) occurs on a slower characteristic timescale of 10-100 s. We show that bulging can be energetically favorable due to the relaxation of the entropic and stretching energies of the inner membrane, cell wall, and outer membrane and that experimentally observed bulge shapes are consistent with model predictions. We then show that swelling can involve both the continued flow of water into the cytoplasm and the enlargement of wall defects, after which cell lysis is consistent with both the inner and outer membranes exceeding characteristic estimates of the yield areal strains of biological membranes. Our results contrast biological membrane physics and the physics of thin shells, reveal principles of how all bacteria likely function in their native states, and may have implications for cellular morphogenesis and antibiotic discovery across different species of bacteria.

Masurkar AAK

Open Access Journal of Microbiology & Biotechnology • 2023

Single Cell Oils (SCO) is of profound interest for a variety of purposes ranging from biofuels to nutritional adjuvants, pharmaceutical applications and biotransformation for valuable products. A number of microorganisms have been shown to produce and accumulate SCO. In the present study a methodical attempt was made to isolate potential SCO producers from Indian water sources. Saltwater samples from the Arabian Sea and freshwater samples from an Indian cold-water river (Pindhari River, Uttarakhand) were collected and studied for the occurrence of lipid producing microbes. Of the several isolates shortlisted as lipid producers three isolates from this study were identified as potential SCO producers based on their lipid producing abilities. The types of fatty acids comprising the SCO from selected isolates were studied by Gas Chromatography (GC) and confirmed by Gas Chromatography/Mass Spectrometry (GC/MS). Lipid profiles from the GC analysis showed that the isolates in this study produced economically and nutritionally valuable Monounsaturated fatty acids (MUFA) like Palmitoleic acid and Oleic acid. Also, two isolates from the Arabian Sea were seen to produce a valuable omega-3 Polyunsaturated Fatty Acid (PUFA) like Eicosapentanoic acid. While a freshwater isolate produced Linoleic acid an omega-6 PUFA. Selected isolates were characterized for their biochemical characteristics and identified molecularly by 16S rRNA sequencing. Ornithinibacillus sp. Marseille-P3601 strain isolated in our study from the cold-water River Pindhari, Uttarakhand is found capable of producing PUFA.

Urania Michaelidou, Annemiek ter Heijne, Gerrit Jan W. Euverink et al.

Applied and Environmental Microbiology • 2011

ABSTRACT Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas -related species that was dominant in the anodic liquid and Pseudomonas -, Clostridium -, Desulfovibrio -, Azospira -, and Aeromonas -related species.

Samir Bensaid, Bernardo Ruggeri, Guido Saracco

Energies • 2015

In this article the concept, the materials and the exploitation potential of a photosynthetic microbial electrochemical cell for the production of hydrogen driven by solar power are investigated. In a photosynthetic microbial electrochemical cell, which is based on photosynthetic microorganisms confined to an anode and heterotrophic bacteria confined to a cathode, water is split by bacteria hosted in the anode bioactive film. The generated electrons are conveyed through external “bio-appendages” developed by the bacteria to transparent nano-pillars made of indium tin oxide (ITO), Fluorine-doped tin oxide (FTO) or other conducting materials, and then transferred to the cathode. On the other hand, the generated protons diffuse to the cathode via a polymer electrolyte membrane, where they are reduced by the electrons by heterotrophic bacteria growing attached to a similar pillared structure as that envisaged for the anode and supplemented with a specific low cost substrate (e.g., organic waste, anaerobic digestion outlet). The generated oxygen is released to the atmosphere or stored, while the produced pure hydrogen leaves the electrode through the porous layers. In addition, the integration of the photosynthetic microbial electrochemical cell system with dark fermentation as acidogenic step of anaerobic digester, which is able to produce additional H2, and the use of microbial fuel cell, feed with the residues of dark fermentation (mainly volatile fatty acids), to produce the necessary extra-bias for the photosynthetic microbial electrochemical cell is here analyzed to reveal the potential benefits to this novel integrated technology.

Justine Papillon, Benoît Ter-Ovanessian, Olivier Ondel et al.

Journal of The Electrochemical Society • 2021

Entangled stainless steel single wire was used as a promising 3D anode for Microbial Fuel Cells (MFCs). Two complementary techniques were coupled to precisely characterize the anode structure and activity: X-Ray Computed Tomography (XRCT) and Electrochemical Impedance Spectroscopy (EIS). XRCT provides an acurate estimation of the pore distribution and size while EIS allows to check and monitor the electrochemical activity. Electrochemical measurements were performed with activated sludges and synthetic medium at an imposed potential of −0.2 V vs Ag/AgCl in a single chamber MFC. Modified Transmission Line Model was used to follow the evolution of the anode in both media including the formation and the growth on the biofilm.