Sayed Zia Mohammadi, Farideh Mousazadeh

Journal of Electrochemical Science and Engineering • 2022

In the current study, a glassy carbon electrode (GCE) modified with graphene-CoS2 nanocomposite was investigated for electrochemical sensing of ascorbic acid. The electrochemical performance of the modified electrode was examined using differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and chronoamperometry (CHA) techniques. The electrochemical behavior of ascorbic acid at the graphene-CoS2/GCE displayed a higher oxidation current and lower oxidation potential than bare GCE. Under the optimal experimental conditions, the sensor presented a good linear response between the current and the ascorbic acid concentration range of 0.15–245.0 μM, with a low detection limit of 0.05 μM. Finally, the graphene-CoS2 nanocomposite-modified GCE was applied for the determination of ascorbic acid in real samples and displayed excellent recoveries.

Farzaneh Shaker, Mohammad Taghi Vardini, Moosa Es’haghi et al.

Rudarsko-geološko-naftni zbornik • 2022

Metal nanoparticles trapped in a biopolymer composite due to electrical conductivity properties improve electrochemical sensors with biomedical and environmental applications. The study aims are to design a novel molecularly imprinted polymer (MIP) composite based on magnetic graphene oxide (Fe3O4@GO) modified silica (SiO2) and gold nanoparticles (AuNPs) to electrochemical detect serotonin (5-hydroxytryptamine, 5-HT). A suitable amount of 5-HT is effective on motivational functions and the environment because it is a serotonergic neurotransmitter. But the desired nanocomposite may have a relatively low recognition, therefore must be in choosing the type of functional monomer be careful. In this regard, the design of the electrochemical sensor began by synthesis of Fe3O4@GO-SiO2@AuNPs nanocomposite. Then, MIP electropolymerization was carried out by using p-aminothiophenol (PATP)-functionalized Fe3O4@GO-SiO2@AuNPs nanocomposite in the presence of 5HT as a template molecule. Electrochemical polymerization of MIP nanocomposite was developed using cyclic voltammetry (CV) and the electrochemical properties of 5-HT were studied use differential pulse voltammetry (DPV) technology in the 5HT solution. After optimization of preparation and measurement conditions on the designed sensor, the 5HT concentration range is 0.1 μM to 10 μM linearly, and the detection limit was 1 × 10-5 μM (S / N = 3). The wide concentration range and low detection limit were presented metal nanoparticles functionalized MIP with appropriate functional monomer have a great effect on the performance of the sensor. Furthermore, PATP-functionalized metal nanoparticles increase the conductivity and recognition of the prepared MIP electrochemical sensor to the quantification of 5-HT in biological samples with high selectivity and recovery.

Raphaël Trouillon

bchm • 2013

Abstract Nitric oxide (NO) is a unique cellular messenger linked to a number of important biological processes. Its free radical nature, small size and fast diffusivity make it highly reactive and membrane permeable. Unfortunately, its reactivity, coupled with the inherent complexity of in situ biological measurements, makes it a challenge to detect. For the past 20 years, electrochemical methods have been used to investigate the role of NO in a number of biological processes, including vascular physiology, immune response, neuronal mediation, tissue growth and oxidative stress. This review examines the biological applications of electrochemical NO sensors and the technologies used to elucidate different physiological phenomena associated with this unique biomolecule with a specific focus on the developments and innovations reported in the last 3 years.

Tadeusz Malinski

Encyclopedia of Electrochemistry • 2002

Abstract The sections in this article are Introduction The Role of Nitric Oxide in Biological Systems NO Release in Biological Systems NO as a Regulator of the Cardiovascular System NO in the Nervous System NO as a Part of the Immune System Pathology of NO Release Electrochemical Methods for NO Detection Electrochemical Oxidation of NO Preparation of Porphyrinic Sensor Operation Modes Clark Probe for NO Detection Measurement of NO in Biological Systems Measurement of NO in a Single Cell In vitro Measurement of NO in Tissue In vivo Measurements of NO in the Kidney In vivo Measurements of NO in the Beating Heart Measurement of NO in the Brain In vitro Measurement with Clark Probe In vivo Measurement with Porphyrinic Sensor Measurements of NO in Human Beings

KOJI TANABE, YOSHITAKA YOSHIZUMI, SHINNOSUKE TSUCHIYA et al.

Electronics and Communications in Japan • 2017

SUMMARY There is a strong interest in onsite rapid analysis and monitoring of the activity of cells and biological samples. Such analyses contribute not only to the understanding of cell functions, but also to the improvement of point‐of‐care testing and quality‐of‐life. In promoting miniaturization and integration of sensing components, electrochemistry is advantageous. By coupling this technique with microfluidic techniques, additional functions that can never be realized with only independent sensors can be realized. In this review paper, we introduce our recent electrochemical devices, particularly focusing on analyses of cell functions and biological samples.

, Chanika Pinyorospathum

• 2018

This research comprised of 2 parts including (1) lab-on-paper coupled with electrochemical method for C-reactive protein and colorimetric detection for phosphate ions and (2) the development of chromatographic techniques and its applications. In each part, it can be classified in 2 works. The first work of lab-on-paper is the electrochemical sensor that was fabricated from phosphorylcholine assembled electrodeposited gold nanoparticles onto screen-printed carbon electrode for C-reactive protein detection. Current of ferrocyanide decrease linearly when increase C-reactive protein concentration from 5.0 – 5000 µg L⁻¹. The calculated detection limit equals 1.60 µg L⁻¹. The final part of lab-on-paper is the colorimetry on paper for phosphate ions using 2-mercaptoethanesulfonate modified silver nanoplates. The color changes rely on anti-aggregation mechanism of modified silver nanoplates and europium ions. The paper-based analytical device can use the naked-eye for detection from purple color changing to pink when increase phosphate concentration. The linearity and detection limit are in the range of 1.0 – 30 mg L⁻¹ and 1.0 mg L⁻¹, respectively. For the development of chromatographic techniques and its applications, the first part is the separation of 4 important insecticides; dinotefuran, thiamethoxam, clothianidin, and imidacloprid using ultra-high-performance liquid chromatography coupled with amperometry detection. The complete separation was finished within 8 minutes using reverse-phase chromatography. The analytical signals increase when employing electrodeposited copper-gold nanoparticles. The detection limit and linear range of 4 significant insecticides were in the range of 0.19 – 0.62 mg L⁻¹ and 1.0 – 250 mg L⁻¹, respectively. The second work is the separation of amino acids using open tubular liquid chromatography. The current signals were measured on copper electrode. The separation of amino acids depends on the ion exchange affinity between quaternary amine on the resin and amino acids. The electrochemical detection arises from the oxidation of copper to form complexes between copper and amino acid. The developed method has detection limit of 0.42 mg L⁻¹. Moreover, all presented methods are simple, fast, and inexpensive. The methods are applied in real samples covering food, environmental compounds, and biomarkers.

Andrea Cognigni, Isabella Ascone, Silvia Zamponi et al.

Journal of Synchrotron Radiation • 2001

A new `quasi-solid state' spectroelectrochemical cell for in situ XAS measurements is described and tested using microperoxidase as reference material. The cell substantially improves conventional thin layer cells used for solution XAS spectroelectrochemistry in terms of assembling time and, more important, equilibration of the redox system under study with the applied potential. Spectra can be, in fact, recorded simultaneously during a slow scan rate cyclic voltammetric scan thus permitting correlation of the spectra and the electrochemical curve. Other advantages are the possibility to use very small quantities of material also with second-generation rings. With high intensity sources having focussed beams a further decrease of the specimen weight can be easily obtained and the acquisition time of spectra further reduced.

, Senzekile Majola

• 2021

Green nanomaterial synthesis has become more popular and, with the need for greener approaches to counter higher costs and higher energy usage for chemical and physical processes, scientists are searching for cheaper methods of synthesis. The use of plant extracts has been one of the popular methods because they are known to reduce metal ions from their surface. Green synthesized nanomaterials are relatively unstable compared to chemical and physical methods hence new stabilizing agents (indole pyrazole ligands) have been introduced in this study. The nanomaterials are being applied in electrochemical and biological systems, their behavior may not be as efficient as the new capped nanomaterials. Hence, a comparison of capped and uncapped nanomaterials was studied. Indole pyrazole capped selenium nanoparticles (TRPIDC-CH3 SeNPs), Indole pyrazole capped silver nanoparticles (TRPIDC-CH3 AgNPs), and Indole pyrazole capped cadmium sulphide quantum dots (TRPIDC-CH3 CdSQDs) were successfully synthesized using plant extracts of allium sativum cloves, pelargonium, and moringa leaves, respectively. Green synthesized TRPIDC-CH3 capped nanomaterials were characterized by UV-vis spectrophotometry, HR-TEM, and FTIR analysis. The results revealed no differences in shape, color, functional groups involved, or wavelength, but an increase in average diameter as compared to uncapped nanomaterials. Furthermore, green-fabricated synthesized nanomaterials were tested to evaluate their cytotoxicity against MCF-7, A549, and HEK293 cells. The overall cytotoxicity was low: a dose-dependent increase in cytotoxic activity was observed for each of the nanomaterials, as the concentration increased from 50 μg/ml to 100 μg/ml. Interaction of TRPIDC-CH3 capped and uncapped nanomaterials with human serum albumin (HSA) was investigated under physiological conditions (PBS, pH 7.3) by UV–Vis, and fluorescence. Fluorescence analysis at different temperatures revealed the quenching of HSA. The results showed a single class of binding site and a static ( uncapped) and dynamic (TRPIDC-CH3 capped) quenching mechanism between nanomaterials and HSA. The thermodynamic results indicated van der Waals forces and hydrogen bonds (uncapped) and hydrophobic interactions (TRPIDC-CH3 capped) were dominant. Dual enzyme electrode for the indirect detection of adenosine triphosphate (ATP),using a redox probe as a reference peak, was developed by co-immobilization of the enzymes glucose oxidase (GO) and hexokinase (Hex) and nanomaterials. The implementation of a simple electrochemical technique to co-immobilize enzymes on electrode surfaces demonstrates a significant improvement in the sensitivity, reproducibility and ease of fabrication of ATP biosensors. However, the addition of the TRPIDC-CH3 ligand to QDs affected the surface area and conductive activity of the sensor leading to a decrease in sensitivity and weakening the electrochemical stability of the QDs. The concept proposed provides the technological basis for a new generation of fast, responsive and robust biosensors for the detection of ATP through indirect detection. Keywords: Adenosine triphosphate (ATP); Indole pyrazole ligand (TRPIDC-CH3); Selenium Nanoparticles (SeNPs); Cyclic voltammetry (CV); Square wave voltammetry (SWV); Hexokinase (Hex); Glucose oxidase (GO); Human serum albumin (HSA); MTT assay; MCF-7, A549, and HEK293 cells.

So Tanabe, Shuyi Sun, Satohiro Itagaki et al.

ECS Meeting Abstracts • 2020

A better understanding of the biological functions of microorganism is required to reduce their threats and increase their usefulness. Therefore, an importance of real-time evaluation of bacterial activity increase for various purposes such as hygiene management, development of antibacterial agents, and effective utilization of bacterial resources. 1 This necessitates a quantitative assessment of metabolic processes, including growth and respiration. Here we would like to introduce the development of electrochemical methods for assessing bacterial activity. Electrochemical detection of viable bacterial cells was performed using cell membrane permeable electron mediator and redox active pigment. Shewanella oneidensis MR-1 transfers electrons generated within the cell to the extracellular environment via the cytochrome complex in the inner/outer membranes and is one of the most useful bacteria for the recovery of metals, treatment of wastewater, and preparation of microbial fuel cells. By using potentiometric measurements, we have examined intracellular electron generation in bacterial suspensions of S. oneidensis supplemented with different carbon sources or ferricyanide, which was almost completely reduced to ferrocyanide during the incubation without affecting bacterial cell viability. 2 On the other hand, a tetrazolium salt (MTT), which was converted to an insoluble reduction form (formazan) through the respiration of microbial cells. 3 The insolubility of this formazan was effectively exploited as a surface-confined redox event. The electrochemical detection of formazan was effectively coupled with the thermal lysis of microbes. The sensitivity of the present technique is up to 10,000-fold higher than that of MTT colorimetry and requires an incubation time of only 1 h, which is approximately 1/4 of that required for other metabolism-based techniques. Furthermore, the measurement of the reduction current of dissolved oxygen provides an effective mean for assessing the respiratory activity of bacteria in suspension. 4 1) T. Kinoshita, K. Ishiki, D. Q. Nguyen, H. Shiigi, T. Nagaoka, Anal. Chem. , 90 (6), 4098 (2018). 2) K. Ishiki, H. Shiigi, Anal. Chem. , 91 (22), 14401-14406 (2019). 3) K. Ishiki, D. Q. Nguyen, A. Morishita, H. Shiigi, T. Nagaoka, Anal. Chem. , 90 (18), 10903 (2018). 4) M. Saito, K. Ishiki, D. Q. Nguyen, H. Shiigi, Anal. Chem. , 91 (20), 12793-12798 (2019).

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Cambridge University Press eBooks • 2006

An emerging theme in molecular and cellular microbiology has been the ability of many pathogens to usurp the host cell and eventually colonize the host. This interaction between bacteria and host is not unidirectional - both pathogens and host cells engage in a signalling cross-talk. Research focused on this cross-talk and discussed in this volume, reveals not only novel aspects of bacterial pathogenesis, but also key information about epithelial biology with broader implications in the prevention and treatment of infectious diseases. Written by leading researchers in this field, this book provides a valuable overview of the host-bacterial interactions that occur at mucosal surfaces including the gastrointestinal, respiratory, and urogenital tracts. It will therefore be a valuable resource for graduate students and researchers working on these systems or in the fields of molecular and cellular microbiology or infectious disease medicine.

Yaniv Shlosberg

bioRxiv (Cold Spring Harbor Laboratory) • 2023

Abstract In recent years, big efforts are done to develop new clean energy technologies that will supply the increasing energy demand without contaminating the environment. One of the approaches is the utilization of live organisms as electron donors in bio-electrochemical cells. Photosynthetic organisms may apply for photocurrent generation, releasing NADPH molecules that are formed in the photosynthetic pathway. In this work, we show for the first time that photocurrent can be harvested directly from a cherry fruit associated with a bio-electrochemical cell. Furthermore, we apply electrochemical and spectroscopic methods to show that NADH in the fruit plays a major role in electric current production.

David C. Sigee

Cambridge University Press eBooks • 1993

Bringing together bacterial structure and function, taxonomy, environmental microbiology, induction and development of plant disease, molecular genetics and disease control, Dr Sigee unifies the field, at the same time as emphasising exciting developments in cell and molecular biology. The book is written in a clear and concise manner, illustrated with numerous tables, diagrams and photographs.

Paola Bardetti, Felix Barber, Enrique R. Rojas

bioRxiv (Cold Spring Harbor Laboratory) • 2024

Abstract The bacillus - or rod - is a pervasive cellular morphology among bacteria. Rod-shaped bacteria elongate without widening by reinforcing their cell wall anisotropically, along the cell’s circumference, but it is unknown how cells adaptively tune anisotropy to homeostatically control cell width. Through super-resolution measurements of cell wall mechanical properties, we discovered that the Bacillus subtilis cell wall exhibits non-linear stress-softening exclusively in the circumferential direction. Furthermore, during steady-state growth the cell wall is inflated precisely to the acute non-linear transition. Physics-based theory correctly predicted that this transition underlies the negative feedback that governs cell width homeostasis. In other words, the cell wall is a “smart material” whose exotic mechanical properties are exquisitely adapted to execute cellular morphogenesis.

Dan Dan

Research Square • 2020

Abstract The field of electrochemistry can be defined as the set of physical and chemical phenomena involved by the passage of an electric current in an ionic conductor. These phenomena involve the use of electrodes characterized by at least one interface common to two conductors of different nature. They manifest themselves in various ways in electrochemical reactors made up of two electronic conductors or electrodes separated by an ionic conductive medium. After having defined the main phenomena involved in the flow of current, the article presents the thermodynamic and kinetic aspects of electrochemistry (electrochemical cell). The main industrial applications of electrochemistry are briefly presented.

Arijit Bag

ChemRxiv • 2017

Extraction of electricity from the salinity gradient of sea water-river water interface has drawn the key interest of sustainable energy researchers. Different technologies are in the spot light − such as pressure retarded osmosis, reverse electrodialysis, ionic diode membrane, mixing entropy battery, microbial fuel cell, etc. In the present work, electrochemical cell equipment is used for this purpose. Two different techniques are described − galvanic cell equipment (GCEQ) and concentration cell equipment (CCEQ). It is observed that, the extracted energy density is very high (up to 95 W m −2 ) compared with the other methods of the same kind reported so far. Implementation of these methods is trivial. Thus, we may conclude that present method will fulfill our requirement of sustainable energy resource.

, Mongkol Tipplook

• 2015

Bacterial cellulose (BC) pellicle is a polysaccharide produced by Acetobacler xylinum. BC pellicle is a good candidate for being used as a wound dressing material because it can provide a moist and promote the wound healing process. However, in a large scale production of BC pellicle the uniformity of thickness of thickness of BC pellicle and its durability are matters of great concerns. In this study, Acetobacter xylinum cells were immobilized on surfaces of a cotton fabric before cultivation in a culture medium in order to produce a BC composite reinforeed with the cotton fabric. Furthermore, a surface treatment of the cotton fabric by using plasma and chemical treatments were performed in order to enhance the attachment of the bacterial cells on the surfaced. The results on cytotoxicity evaluated by MTT assay indicated that the BC composites were non-toxic to L929 cells. The SEM images showed that density of cellulose fibers attached on the cotton fabric was greater than non-immobilized one. Although the production yields of BC composites obtained by applying cell immobilization techniques were slightly less than that produced by traditional techniques (non-immobilization), the use of less starting cell inoculum and the uniformity of BC deposited on the cotton fabric are the benefits of applying cell immobilization on the production of BC composites.

S. Keerthana, K. P. Divya, A. Rajapriya et al.

Research Square • 2024

Abstract Pyocyanin (PYO) is a distinctive electroactive virulence factor secreted by Pseudomonas aeruginosa , a bacterium implicated in a spectrum of severe human infections, particularly in susceptible and critically ill patients. The rapid and accurate diagnosis of infectious agents is crucial for prescribing effective antibiotics and ensuring successful treatment outcomes in patients facing critical conditions. Due to its redox-active nature, PYO actively participates in electron acceptance and donation processes at the electrode surface, making it well-suited for electrochemical detection. To enhance this detection capability, we utilized a physically cross-linked methodology to embellish the surface of a working electrode with a nanocomposite composed of tungsten disulfide nanosheets supported by nanodiamond (WS 2 NSs-ND). This innovative approach was implemented to enhance electron transport, and sample absorption on the electrode surface with a sensitivity of 0.38 µA µM − 1 cmdue to its increased number of active sites. Furthermore, WS 2 NSs-ND demonstrated remarkable electrochemical performance when applied to real sample human urine, yielding RSD of ± 2%. This underscores the reliability and robustness of WS 2 NSs-ND/GCE for the accurate detection of PYO in diverse biological samples, showcasing its potential for clinical applications.

S. Prabhavathi, Swapna M. Gali, Kiran Kumar Tadi et al.

Journal of The Electrochemical Society • 2025

Biofilms pose challenges such as infection transmission, biofouling, equipment failure, and environmental damage. Despite extensive research, their detection in bioenvironmental systems remains a significant challenge for researchers. Electrochemical impedance spectroscopy (EIS) stands out as an exceptionally sensitive and non-destructive technique for real-time monitoring of biofilms. In this study, we employed EIS to investigate the biofilm formation dynamics of the gram-positive bacterium Staphylococcus aureus ( S.aureus ) on indium-titanium oxide (ITO)-coated polyethylene terephthalate (PET) conductive substrates. Comprehensive characterization of both control and biofilm-coated substrates was carried out using. The temporal evolution of S.aureus biofilm growth was tracked through EIS measurements, revealing a substantial increase in charge transfer resistance as the biofilm matured. The extracellular electron transfer between the biofilm-coated electrode and the electrolyte was assessed by modulating the EIS bias potential at open circuit potential. Linear response in the charge transfer resistance with increased concentration of S.aureus was studied from 1.0 × 10 5 to 1.0 × 10 7 CFU ml −1 with a limit of detection of 3.5 × 10 4 . Overall, this work presents a simple yet highly sensitive biosensor for biofilm detection and growth analysis, eliminating the need for complex substrate modifications.

Πέτρος Σακκάς

• 2016

Για τη σύνθεση νανοσωματιδίων οξειδίων των μετάλλων και μετάλλων χρησιμοποιήθηκαν αντίστοιχα μέθοδοι ηχοχημείας και ηχοηλεκτροχημείας. Ταυτόχρονα, με τη δράση των υπερήχων, επιτεύχθηκε διακόσμηση (decoration) τεχνολογικώς ώριμων σκονών ανόδων κυψελών καυσίμων. Οι τροποποιημένες σκόνες μπορούν να χρησιμοποιηθούν στην πλευρά της ανόδου κυψελών στερεού οξειδίου και μεμβράνης εναλλαγής πρωτονίων. Στην περίπτωση της ηχοχημικής σύνθεσης, οργανομεταλλικές ενώσεις διαλελυμένες σε οργανικούς διαλύτες αποτέλεσαν τα πρόδρομα υλικά ενώ κατά την ηχοηλεκτροχημική σύνθεση, άλατα μετάλλων σε υδατικό διάλυμμα έδωσαν νανοσωματίδια μετάλλων με τη βοήθεια σταθεροποιητών οργανικής σύστασης.Οι νανοσχηματισμοί οξειδίων των μετάλλων που συντέθηκαν ήταν αυτοί του βολφραμίου, μολυβδαινίου και ρηνίου, ενώ τα νανοσωματίδια μετάλων που συντέθηκαν ήταν αυτά του χρυσού, του χαλκού και της πλατίνας. Κάθε είδος υλικού που προετοιμάστηκε, διακοσμήθηκε τελικώς επί σκόνης μηχανικού μίγματος οξειδίου του νικελίου και τροποποιημένης με γαδολίνιο δημητρίας. Εκτός αυτών, σωματίδια carbon black διακοσμήθηκαν με νανοσωματίδια πλατίνας. Το carbon black αποτελεί μια ενεργοποιημένη μορφή άνθρακα η οποία χρησιμοποιείται κατά κόρον σε μεμβράνες εναλλαγής πρωτονίων. Ως εκ τούτου, ένας από τους κυριότερους στόχους των τεχνικών διακόσμησης που αναπτύχθηκαν σε αυτή τη μελέτη ήταν ο έλεγχος της φόρτισης νανοσχηματισμών επί σωματιδίων σκόνης υποστρώματος. Την ίδια στιγμή, η μέθοδος διακόσμησης ήταν σημαντικό ν' αφήνει αρκετή εκτεθειμένη επιφάνεια διαθέσιμη ώστε να μπορούν να λειτουργούν ως αναμένται στην άνοδο μια κυψέλης καυσίμου.Η ηχοχημεία οφείλει τη δύναμή της στα κύματα υπερήχων τα οποία προκαλούνται εντός ενός υγρού μέσου. Τα κύματα αυτά δημιουργούν κατά τόπους στο υγρό απειροελάχιστες κοιλότητες, οι οποίες αυξομειώνονται περιοδικά με το χρόνο έως ότου φτάνουν σε ένα μέγεθος στο οποίο καταρρέουν. Κατά την κατάρρευση, όλες οι αέριες ουσίες οι οποίες καταλάμβαναν την κοιλότητα εξαναγκάζονται να συσσωρευθούν σε ένα απειροελάχιστο σημείο στο κέντρο της τέως ζώσας κοιλότητας. Σε αυτό ακριβώς το σημείο αναπτύσσονται ιδιαίτερα αυξημένες ποσότητες θερμοκρασίας και πίεσης, και μάλιστα μέσα σε ένα εξαιρετικά βραχύ χρονικό διάστημα. Κάτω από αυτές τις συνθήκες είναι πλέον δυνατόν να συντεθούν νανοϋλικά.Στην ηχοηλεκτροχημεία, εξ άλλου, χρησιμοποιείται η μέθοδος της ηλεκτροαπόθεσης ούτως ώστε να επιτραπεί η σύνθεση και ανάπτυξη σωματιδίων των μετάλων επί της ελεύθερης μεταλλικής επιφάνειας του ηλεκτροδίου εργασίας. Ακολούθως, αξιοποιείται η δράση του υπερήχου έτσι ώστε να επιτύχει την απόσχιση σωματιδίοων από το ηλεκτρόδιο. Με αυτό τον τρόπο λαμβάνει χώρα η σύνθεση και καθαρών μετάλλων νανομετρικής κλίμακας.Για τη σύνθεση νανοσωματιδίων οξειδίων των μετάλλων του βολφραμίου, του μολυβδαινίου και του ρηνίου χρησιμοποιήθηκαν αντίστοιχα οι πρόδρομες ουσίες W(CO)$_6$, Mo(CO)$_6$ και Re$_2$(CO)$_{10}$. Από την άλλη, τα πειράματα που σχεδιάστηκαν με στόχο τη σύνθεση νανοσωματιδίων μεταλλικού χρυσού, χαλκού και πλατίνας συμπεριλάμβαναν αντίστοιχα τις πρόδρομες ουσίες HAuCl$_{4}\cdot$3H$_2$O, CuSO$_{4}\cdot$5H$_2$O και PtCl$_{6}\cdot$H$_{2}$O. Στα υδατικά πρόδρομα διαλύματα πραγματοποιήθηκε επίσης ρύθμιση του pH με την προσθήκη των σχετικών αντιδραστηρίων. Σε κάθε περίπτωση προστέθηκε poly(N-vinyl-2-pyrrolidone) ως επιφανειοδραστική ουσία η οποία δρα ως ανασταλτικός παραγών ως προς την ανάπτυξη μεγάλων κρυσταλλικών δομών. Ως υλικά προς διακόσμηση χρησιμοποιήθηκαν NiO/GDC και carbon balck, τα οποία χρησιμοποιήθηκαν ακριβώς όπως αγοράσθηκαν από σχετικές εταιρίες σύνθεσης υλικών κυψελών καυσίμων.Τα πειράματα σύνθεσης οξειδίων των μετάλλων έδειξαν ότι η ένταση των υπερήχων όπως και το είδος του οργανικού διαλύτη που χρησιμοποιείται είναι σε θέση να επιδράσουν στην τελική διασπορά μεγέθους όπως επίσης και μορφολογία των δημιουργούμενων νανοσχηματισμών. Την ίδια στιγμή, ο λόγος βάρους πρόδρομης ουσίας και υποστρώματος όπως επίσης η ένταση και διάρκεια του υπερήχουβρέθηκαν να επηρεάζουν την έκταση της φόρτισης των νανοσχηματισμών επί του υποστρώματος. Ηλεκτρονική μικροσκοπία διερχόμενης δέσμης (TEM) χρησιμοποιήθηκε κυρίως για την αναγνώριση του τελικού προϊόντος όπως αυτό προέκυψε σε κάθε προσπάθεια σύνθεσης. Επιπροσθέτως, χαρακτηριστικές νανομορφολογίες εξετάσθκαν με σκεδασμό ηλεκτρονίων επί επιλεγμένων περιοχών (SAED) και έδωσαν σημαντικές πληροφορίες σχετικά με την νανοκρυσταλλικότητα και στοιχειομετρία όλων των υλικών που συντέθηκαν.Η πειραματική διαδικασία σύνθεσης νανοσωματιδίων των μετάλλων ακολούθησε μια αρχή παλμικής ηλεκτροαπόθεσης ακολουθούμενης από ένα βραχύ διάστημα δράσης υπερήχου. Ο κύκλος αυτός συνεχίστηκε έως ότου επιτευχθεί ένα σχετικά πυκνό κολλοείδες διάλυμα σωματιδίων μετάλλου, τα οποία θα διατηρούσαν το μέγεθός τους και διασπορά λόγω του επιφανειοδραστικού που χρησιμοποιήθηκε. Κολλοειδή διαλύματα ηχοβολήθηκαν κατόπιν μαζί με σκόνη υποστρώματος η οποία βρέθηκε σε αιώρηση. Απεδείχθη ότι τα νανοσωματίδια του κολλοειδούς διαλύματος μπορούν να δικοσμηθούν επί των σωματιδίων της σκόνης υποστρώματος. Στην περίπτωση της πλατίνας χρησιμοποιήθηκε μια άλλη προσέγγιση. Το carbon black βρέθηκε σε αιώρηση εντός του πρόδρομου διαλύματος με αποτέλεσμα κατά τη σύνθεση των νανοσωματιδίων πλατίνας να λάβει χώρα in-situ η διακόσμηση των σωματιδίων carbon black. Εκτός της μικροσκοπίας TEM, η χρήση της δυναμικής σκέδασης του φωτός (DLS) βοήθησε πολύ στο να καθοριστούν οι διάρκειες των επί μέρους παλμών.Όλες οι τιμές φόρτισης των διακοσμήσεων αποφασίσθηκαν με βάση τη βιβλιογραφία. Ο απότερος στόχος ήταν ο καθορισμός μεθόδου που θα μπορούσε να δώσει υλικό με κατάλληλες φορτίσεις έτσι ώστε το ίδιο να χρησιμοποιηθεί σε πειραματικές διατάξεις κυψελών καυσίμου. Επιπροσθέτως, οι διακοσμημένες σκόνες που προετοιμάσθηκαν κατά την παρούσα μελέτη εστάλησαν και δοκιμάστηκαν σε διάταξη θερμοκρασιακά προγραμματιζόμενης αναγωγής \& οξείδωσης (TPR \& TPO). Ως εκ τούτου τα υλικά που συντέθηακν απεδείχθη ότι μπορούν να ενισχύσουν τη διαδικασία υγρής αναμόρφωσης του μεθανίου, του κυριότερου συστατικού του φυσικού αερίου.

Eric Frantz, Andrew Steckl

ECS Meeting Abstracts • 2020

Bacteria are one of the most common sources of illness, responsible for a wide range of infections. Bacterial infections can be caused from a variety of sources, with thousands of deaths attributed to waterborne outbreaks alone [ 1 ]. Detection of both infectious and non-infectious bacteria is utilized to ensure commercial goods and water are safe for consumers. Current detection of bacterial contamination typically uses cell culture plates to measure the number of colony forming bacteria (CFU/ml) in a liquid media. This technique is widely used due to its high sensitivity and easy visual readout. Unfortunately, culture counting techniques is time consuming (1-3 days), requires skilled lab technicians, can be contaminated during preparation, and cannot be integrated into the desired testing media directly. To overcome these limitations, many bacterial sensors and detection techniques have been developed over the last few decades [ 2 ]. A recent sensor for bacteria detection is the organic electrochemical transistor (OECT). OECTs are polymer-based transistors that utilize ionic solutions to de-dope and re-dope a conducting channel. These devices are known for their high transconductance, bio-compatibility, low operating voltage, low cost, small size, ease of integration into measurement systems, and ability to function in aqueous environments [ 3 ]. Detection of a single bacteria is typically desired and achieved through the capture of bacteria cells onto the OECT channel area [ 4 ]. This approach allows for rapid detection of a specific pathogen with high sensitivity. However, for detecting contamination from a variety of bacteria a different approach must be used. We have investigated the OECT response to the presence of non-captured bacteria present within the OECT operating media. In this approach cells are detected both in solution and on the surface of the source-drain channel and on the gate electrode. Presence of bacteria between the gate and channel region will cause an increase in effective gate voltage, resulting in a decrease in source-drain current. Detection and characterization of (non-bacteria) whole cells has previously been reported utilizing this approach [ 5 , 6 ]. In our work we have focused on the bacteria pseudomonas fluorescens (p. fluorescens) due to its size (~1µm) and potential as a water borne pathogen. P. fluorescens was cultured in LB media, diluted to three different concentrations, and used as the operating media for OECT. Concentrations of 8.7e12, 8.7e11, and 8.7e10 CFU/ml were found to shift source-drain current by 16.1, 13.8, and 12.3µA, respectively. From this data a present lower limit of detection for the sensor is estimated to be ~5.0e4 CFU/ml. 1. Craun, G.F., Statistics of waterborne outbreaks in the US (1920–1980). Waterborne diseases in the United States, 2018: p. 73-159. 2. Ahmed, A., et al., Biosensors for whole-cell bacterial detection. Clinical microbiology reviews, 2014. 27(3): p. 631-646. 3. Strakosas, X., M. Bongo, and R.M. Owens, The organic electrochemical transistor for biological applications. Journal of Applied Polymer Science, 2015. 132(15). 4. Demuru, S., et al. Flexible Organic Electrochemical Transistor with Functionalized Inkjet-Printed Gold Gate for Bacteria Sensing. in 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII). 2019. IEEE. 5. Liao, J., et al., Organic electrochemical transistor based biosensor for detecting marine diatoms in seawater medium. Sensors and Actuators B: Chemical, 2014. 203: p. 677-682. 6. Ramuz, M., et al., Monitoring of cell layer coverage and differentiation with the organic electrochemical transistor. Journal of Materials Chemistry B, 2015. 3(29): p. 5971-5977. Figure 1

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Cambridge University Press eBooks • 2006

Many bacterial diseases are caused by organisms growing together as communities or biofilms. These microorganisms have the capacity to coordinately regulate specific sets of genes by sensing and communicating amongst themselves utilizing a variety of signals. This book examines the mechanisms of quorum sensing and cell-to-cell communication in bacteria and the roles that these processes play in regulating virulence, bacterial interactions with host tissues, and microbial development. Recent studies suggest that microbial cell-to-cell communication plays an important role in the pathogenesis of a variety of disease processes. Furthermore, some bacterial signal molecules may possess immunomodulatory activity. Thus, understanding the mechanisms and outcomes of bacterial cell-to-cell communication has important implications for appreciating host-pathogen interactions and ultimately may provide new targets for antimicrobial therapies that block or interfere with these communication networks.

, Yang Xu

• 2024

Although there has been significant progress in the understanding of the mechanism and regulation of bacterial cell envelope biogenesis, further exploration is required to fully understand the bacterial cell envelope and its synthesis machineries and develop new methods to kill bacteria. This thesis aims to showcase the fluorescent labeling methods for studying bacterial cell wall envelopes and their application in studying outer membrane (OM) permeability and killing antibiotic-resistant pathogens. The assays involve chemical and chemoenzymatic synthesis, advanced microscopy techniques, and microorganism assays, and expand the toolbox of labeling bacteria and make it more accessible to a wider range of researchers. Chapter 2 describes a fluorescent labeling method that can label the newly synthesized lipopolysaccharides (LPS) of Gram-negative bacteria using azido-galactose, which is a common monosaccharide in bacterial LPS. This method provides a new way to specifically label Gram-negative bacteria through a click-chemistry reaction. Chapter 3 outlines a labeling strategy for peptidoglycan (PG) by functionalizing GlcNAc. This one-step biosynthesis of UDP-GlcNAz serves as an intermediate for incorporation into PG, allowing for labeling of the glycan core of PG. This approach provides a complementary labeling strategy for bacterial labeling that targets a different component than the previous study. The study is published in iScience in 2022. Chapter 4 describes the photodynamic inactivation of antibiotic-resistant pathogens using chemical photosensitizers, including photoactive D-amino acid derivatives and antibiotic photosensitizers. The killing mechanisms involve the incorporation of D-amino acids, penicillin-binding protein (PBP) binding, and D-ala-D-ala binding, leading to membrane damage and efficient killing of MRSA and VISA. Chapter 5 investigates OM permeability through a designed approach of labeling peptidoglycan with trans-cyclooctenes (TCO) and using fluorogenic probes to indicate OM permeability through the strain-promoted inverse electron-demanding Diels-Alder cycloaddition (SPIEDAC) reaction. This provides a direct method to indicate OM permeability. In summary, this thesis showcases new and complementary fluorescent labeling methods for bacterial components and their applications in studying OM permeability and killing antibiotic-resistant pathogens. These methods expand the toolbox of labeling bacteria and provide useful tools for researchers to study bacterial cell envelope biogenesis.

Wenfa Ng

• 2017

Bacteria surface charge mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface, where repeated centrifugation and washing by buffers is the gold standard method for sample preparation. Unfortunately, the need for time consuming centrifugation limits the temporal resolution of sampling and profiling of experiment system dynamics; especially for samples requiring immediate treatment after sampling. Herein, the feasibility of diluting cell aliquots with buffer as a single step sample preparation technique for surface charge measurement was investigated by characterizing the effects of dilution ratio, cation type, and buffer conductivity on measuring surface charge of Escherichia coli DH5α (ATCC 53868) grown in LB Lennox medium. Results indicated that dilution ratio was critical to accurate surface charge measurement since poor signal-to-noise ratio in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the negatively-charged cell surface underestimated surface charge. Finally, high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening; however, a broader statistical distribution of measured surface charge and less accurate data were also observed. At extreme conductivity values, measured surface charge exhibited multi-modal distribution; due probably to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites, and called into question the accuracy of data. Altogether, one step dilution of cell aliquot with deionized water reliably reproduced E. coli surface charge values obtained using the gold standard approach. But, since the ensemble of secreted metabolites is bacteria and medium specific, distinct diluent and experimental parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterization studies, where it would help reduce sample preparation time, and thus, improve temporal resolution at which scientific questions can be probed and answered.

Nikola Ojkic, Shiladitya Banerjee

bioRxiv (Cold Spring Harbor Laboratory) • 2021

ABSTRACT By analysing cell shape and size of the bacterium Bacillus subtilis under nutrient perturbations, protein depletion, and antibiotic treatments we find that cell geometry is extremely robust, reflected in a well-conserved scaling relation between surface area ( S ) and volume ( V ), S ~ V γ , with γ = 0.85. We develop a molecular model supported by single-cell simulations to predict that the surface-to-volume scaling exponent γ is regulated by nutrient-dependent production of metabolic enzymes that act as cell division inhibitors in bacteria. Using theory that is supported by experimental data, we predict the modes of cell shape transformations in different bacterial species and propose a mechanism of cell shape adaptation to different nutrient perturbations. For organisms with high surface-to-volume scaling exponent γ , such as B. subtilis , cell width is not sensitive to growth rate changes, whereas organisms with low γ , such as A. baumannii , cell shape adapts readily to growth rate changes. SIGNIFICANCE How bacteria regulate their size and shapes to optimise their growth fitness in different nutrient environments remains largely unknown. By analysing the surface area and volume of rod-shaped B. subtilis exposed to different nutrient conditions and antibiotics we find that cells preserve a power law scaling between surface area and volume. We show that the surface-to-volume scaling is extremely robust and is regulated by nutrient-dependent synthesis of cell division inhibitors. By analysing different bacterial types, we find that cells conserve the surface-to-volume scaling exponent that is typical for each species, implying distinct mechanisms for morphological adaptation in each organism.

Aida Ebrahimi

ECS Meeting Abstracts • 2022

Traditional methods for bacterial detection and analysis are time consuming, labor-demanding, and have limited portability. This presents a significant opportunity for biosensor engineers to develop low-cost devices for bacterial studies. In this talk, I will discuss our recent advances in developing electrochemical biosensing devices for bacterial analysis. The devices enable characterizing cell envelope, metabolic activity, and quorum sensing molecules, and can provide real-time insight into bacterial response to environmental stress, such as drugs. The sensors feature functional materials to achieve specificity and sensitivity for analysis of real samples. Depending on the need, the biosensors are manufactured using a combination of different device fabrication methods, including standard microfabrication, electrodeposition, printing, and laser engraving of plastic and paper. Specifically, owing to compatibility with additive manufacturing and having rich active sites for functionalization, direct laser engraving enables rapid prototyping of low-cost sensors for a wide range of stand-alone diagnostic platforms.

Hiroshi Shiigi

ECS Meeting Abstracts • 2024

A better understanding of the biological functions of microorganisms is required to reduce their threats and increase their usefulness. Therefore, the importance of real-time evaluation of bacterial activity increases for various purposes such as hygiene management, development of antibacterial agents, and effective utilization of bacterial resources. 1 This necessitates a quantitative assessment of metabolic processes, including growth and respiration. Here we would like to introduce the development of electrochemical methods for assessing bacterial activity. Electrochemical detection of viable bacterial cells was performed using cell membrane permeable electron mediator and redox-active pigment. On the other hand, a tetrazolium salt (MTT), was converted to an insoluble reduction form (formazan) through the respiration of microbial cells. 2 The insolubility of this formazan was effectively exploited as a surface-confined redox event. The electrochemical detection of formazan was effectively coupled with the thermal lysis of microbes. The sensitivity of the present technique is up to 10,000-fold higher than that of MTT colorimetry and requires an incubation time of only 1 h, which is approximately 1/4 of that required for other metabolism-based techniques. On the other hand, Considering that oxidized MTT, which has excellent cell membrane permeability, changes into insoluble reduced formazan within cells, it is also possible to estimate the number of viable cells by focusing on the reduction current of MTT remaining in the suspension. was. Dissolved oxygen is an important substance for bacterial activity. When live bacteria in suspension were observed in real-time, it was found that uptake of MTT into bacteria was completed within 10 minutes, including the lag period. Furthermore, we also observed that the current response was dependent on viable cell density, regardless of the bacterial species present. This method allows us to quickly estimate the number of viable bacteria, making it possible to confirm the safety of food before it leaves the factory and prevent food poisoning. 3 Furthermore, the measurement of the reduction current of dissolved oxygen provides an effective means for assessing the respiratory activity of bacteria in suspension. 4 Organometallic nanohybrids (NHs), in which many small metal nanoparticles are encapsulated within a conductive polymer matrix, are useful as sensitive electrochemical labels because their components produce characteristic oxidation current responses. NHs made of metal nanoparticles such as gold or copper and polyaniline did not interfere with each other in terms of electrochemical signals obtained on the same electrode. Antibodies were introduced into these NHs that served as electrochemical labels to target specific bacteria. Electrochemical measurements using screen-printed electrodes dry-fixed with NH-labeled bacterial cells allowed the bacterial species and number to be estimated within minutes based on the distinct current response of the label. Our proposed method achieved simultaneous detection of enterohemorrhagic E. coli and Staphylococcus aureus in real samples. These NHs are expected to be a powerful tool as electrochemical labels and useful for rapid testing at food and pharmaceutical manufacturing sites. 5 1) T. Kinoshita, K. Ishiki, D. Q. Nguyen, H. Shiigi, T. Nagaoka, Anal. Chem. , 90 , 4098 (2018). 2) K. Ishiki, D. Q. Nguyen, A. Morishita, H. Shiigi, T. Nagaoka, Anal. Chem. , 90 , 10903 (2018). 3) H. Ikeda, A. Tokonami, S. Nishii, X. Shan, Y. Yamamoto, Y. Sadanaga, Z. Chen, and H. Shiigi, Anal. Chem. , 95 , 12358-12364 (2023). 4) M. Saito, K. Ishiki, D. Q. Nguyen, H. Shiigi, Anal. Chem. , 91 , 12793-12798 (2019). 5) S. Itagaki, A. Nakao, S. Nakamura, M. Fujita, S. Nishii, Y. Yamamoto, Y. Sadanaga, H. Shiigi, Anal. Chem. , 96 , 3787-3793 (2024).

So Tanabe, Shuyi Sun, Satohiro Itagaki et al.

• 2020

For the efficient utilization of bacterial bioresources, the quantitative evaluation of metabolic activity in live bacterial cells is required. Using potentiometric measurements, we quantitatively evaluated the electron generation rate of Shewanella oneidensis MR-1 based on individual enzymatic reactions. We evaluated intracellular electron generation in bacterial suspensions supplemented with different carbon sources utilized in the tricarboxylic acid cycle. In bacterial suspensions, ferricyanide was almost completely reduced to ferrocyanide by cell-generated electrons, without an effect on bacterial cell viability. Focusing on this reduction reaction, quantitative evaluations were possible by potentiometry based on the Nernst equation.

Hikaru Ikeda, Akira Tokonami, Hayato Fujimura et al.

ECS Meeting Abstracts • 2024

【Introduction】 Bacterial activity is an essential evaluation index for hygiene management and quality control of medicine and food because some bacteria such as Escherichia coli , Salmonella enterica , and Staphylococcus aureus are causative organisms that cause food poisoning and adversely affect the human body. Conventional bacterial testing has widely used methods that count colonies formed based on cell proliferation in culture. When the mother cell divides to produce her two daughter cells, the surviving cells multiply logarithmically. Most bacteria divide at least once within an hour, but some species take longer than 20 hours to divide, so visual confirmation of bacterial colonization may take at least 48 hours, and in some cases about 2 weeks. Hence, although this method reflects viability with accurate cell counts, it requires a long inspection time. A rapid and simple technique for bacterial detection based on dissolved oxygen, enzymatic reactions, and electron mediators was developed to circumvent this problem. This study focused on the electrochemical properties of tetrazolium salts to develop a simple method for evaluating viable bacterial counts, which are indicators of hygiene control at food and pharmaceutical manufacturing sites [1]. Given that the oxidized form of 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which has excellent cell membrane permeability, changes to the insoluble reduced form of formazan inside the cells. The number of viable cells was estimated by focusing on the reduction current of MTT remaining in the suspension. Dissolved oxygen is an important substance for bacterial activity; however, it interferes with the electrochemical response of MTT. We investigated the electrochemical properties of MTT to obtain a potential-selective current response that was not affected by dissolved oxygen. Real-time observation of viable bacteria in suspension revealed that uptake of MTT into bacteria was completed within 10 min. In addition, we observed that the current response depends on viable cell density regardless of the bacterial species present. Our method enables a rapid estimation of the number of viable bacteria, making it possible to confirm the safety of food products before they are shipped from the factory and thereby prevent food poisoning. 【Experimental】MTT solution and 0.20% glucose-added nutrient broth medium were mixed and diluted with electrolytes, such as 0.10 M KCl aqueous solution and 0.10 M phosphate-buffered saline (PBS) solution (pH 7.4), to obtain 0.10 mM MTT solution. E. coli suspension (2.0 × 10 9 CFU mL － 1 ) was dropped into 0.10 mM MTT solution and incubated at 310 K for 1 h. Cyclic voltammetry (CV) was performed to measure MTT remaining in the suspension before and after incubation at a sweep rate of 0.10 Vs － 1 using a glassy carbon-disk electrode as the working electrode, a platinum coil as the counter electrode, and Ag|AgCl (3 M KCl) as the reference electrode. 【Results】Two sharp reduction peaks were observed at －0.1 V ( II c ) and －0.6 V ( I c ) at performing a cathode sweep from +0.2 V (Fig.1). These current responses are based on the reactions shown in the following equations. MTT + e － ⇄ MTT ・ （intermediate） [1] MTT ・ + H + + e － ⇄ formazan [2] The MTT-based current responses remaining in these electrolytes gradually decreased with incubation time and almost disappeared after 60 min of incubation. This means that MTT was taken up into cells and the generated insoluble formazan was deposited inside the cells. Although dissolved oxygen is certainly an important substance for bacterial activity, it can interfere with the electrochemical response of MTT. The current response of formazan formation ( I c ) was significantly different in the presence of dissolved oxygen (12%). However, the current response based on the intermediate formation reaction ( II c ) was unaffected (0%). Quantification of viable bacterial counts based on the current response of II c (10 3 –10 7 CFU mL － 1 ) was achieved by measuring the amount of residual MTT in the electrolyte. Furthermore, the current response was confirmed to be dependent on viable cell density, independent of bacterial wall structure and metabolic processes. 【Reference】 [1] H. Ikeda, A. Tokonami, S. Nishii, Y. Yamamoto, X. Shan, Y. Sadanaga, H. Shiigi, Anal. Chem. , 95 (33), 12358-12364 (2023). 【Images】 Fig.1 CVs of 0.10 mM MTT in 0.10 M PBS solution (pH 7.4) containing E. coli (2.0×10 9 CFU mL −1 ) during incubation at 310 K. Figure 1

, Yongqiang Yang

• 2020

Even though rapid detection of molecular methods has been used in bacterial detection, (automated) liquid culture methods are still the "Gold Standard" for the detection of living bacteria, especially in cases where there may be similar dead bacteria also present in the sample. However, the current liquid culture methods rely on the effects of bacterial metabolism (changes in O2/CO2 levels, pH, etc.) to bring about measurable changes to the suspension. Hence, for slow-growing microorganisms like M. tuberculosis (Mtb), they take a long time (up to 6 weeks) to yield results. To cut the time to positivity, we applied the detection concept of "detection by death" and using our high sensitivity microchannel Electrical Impedance Spectroscopy (m-EIS) method to detect bacteria in various samples rapidly. Viable bacterial cells can be killed in a few hours with very high doses of cidal drugs. m-EIS relies on the fact that high-frequency AC fields cause transient charge-accumulation at live cells' intact membranes. Cell-death in the microchannel causes charges to no-longer be accumulated, and the bulk capacitance of the microchannel will decrease. By picking up this change, we can rapidly detect viable bacterial cells in a testing sample. For viable TB bacteria detection, we use synthetic sputum with gram-positive bacteria, gram-negative bacteria, and M. tuberculosis H37ra. After decontamination (kill all non-TB bacteria), we are able to discern decreases in bulk-capacitance for suspensions containing ~500 CFU/ml of Mtb cells (but not for ~50 CFU/ml). Thus, our turnaround-time (~4 hours) and limit-of-detection ([less than]500 CFU/ml) are comparable to those of GeneXpertTM. Using our m-EIS method, we can also detect Lactic Acid Bacterial (LAB) contamination for ethanol fermentation with a low concentration of 5000 CFU/ml in less than 3 hours. Our detection of limit for LAB has a three-order reduction than the HPLC method, but with a similar detection time. Aside from investigating the bacterial activities in the solution, we also observed the biofilm formation on the electrodes. We have observed that the interfacial capacitance also increases in proportion to the number of cells in the biofilm matrixes. In the future, we believe that we could also record cell death within biofilm using our method, and so researchers will be able to use it to screen new anti-biofilm material and drug rapidly.

Chia-Hung Hou, Chih-Yu Ma

ECS Meeting Abstracts • 2017

Due to unstainable use of natural water resources, alternative water resources such as brackish water and seawater desalination have been an emerging solution. However, development of desalination capacity is limited due to the high energy requirements for removing salt ions from water. Currently, capacitive deionization technology (CDI), following the working principle of supercapacitors, has attracted considerable attention from academia, industry, and government agency. As compared to conventional desalination technologies, CDI has several advantages including low energy consumption, easy regeneration, high water recovery, and no secondary waste. In CDI, by applying an external electric filed between two parallel of nanoporous carbon electrodes (i.e., carbon aerogel, activated carbons, carbon nanotubes, and graphene), ions can be stored at the electrode/solution interface via electrical double layer (EDL) formation. Additionally, microbial desalination cell (MDC) is a new bioelectrochemical technology for seawater desalination with simultaneous electricity generation and wastewater treatment. Basically, a MDC reactor contains an anode chamber, a desalination chamber, and a cathode chamber. In MDC, microorganisms can oxidize organic waters in wastewater to harvest electric energy, and meanwhile, salt ions can be removed during the electricity generating process. In this study, we propose a hybrid electrochemical desalination system for seawater desalination by coupling CDI device with a MDC reactor. As a result, MDC produced electricity with open circuit voltage of 0.8 V and a current of 3 mA by using bacteria to degrade organic contaminants through anode bacterial oxidation and cathode reduction. In MDC, 91% removal of chemical oxygen demand (COD) in synthetic wastewater can be achieved, and the solution conductivity can be reduced from 17,000 µS/cm to about 200 µS/cm. More importantly, CDI device can be driven by electricity harvesting from the two MDCs in parallel, and as the downstream desalination process to further desalinate salt water. The results of this study can demonstrate the feasibility of the integrated electrochemical MDC-CDI system for simultaneous wastewater treatment, power production, and water desalination. .

Wesley R. Browne

Electrochemistry • 2018

This chapter focuses on the electrochemical cell. It discusses electrode polarization in terms of the relationship between electrochemical cells and capacitors. The chapter also lists classifications of electrodes. These vary between the first, second, or third. It explores the process of achieving Galvanic (voltaic) cells. Next, the chapter cites how half-cell reactions are presented as being reduced by convention. The chapter also looks into the potential of a half-cell. It also presents the Nernst equations which relate the potential of a cell or half-cell to the actual concentration of the present species and standard reduction potential. The chapter then notes redox chemistry by referencing Latimer diagrams, Frost diagrams, Pourbaix diagrams, and Ellingham diagrams.

Yang Bae Jeon, Fusheng Tang, Jin Wook Lee

ECS Meeting Abstracts • 2015

Microbial biofuel cells produce electricity directly from organic fuels such as glucose sucrose, acetates and ethanol. In the present work, electrochemical characteristics of the yeast-catalyzed half cell against carbon cloth electrode with various yeasts and with immobilization are investigated experimentally. Three types of yeasts as anode catalyst are employed: (1) commercially available baker’s yeast (S. Cerevisiae); (2) wild type yeast cultured in our lab; and (3) respiration-free mutant yeast. Kinetic parameters for the three types of yeasts are obtained by Tafel analysis. Cyclic voltammetry (CV) techniques are applied to investigate the reversibility of the redox reactions. Open current potential (OCP) of each yeast is measured against a reference electrode to estimate the anodic potential. Electrochemical impedance spectroscopy (EIS) of the half-cell is conducted to estimate the resistivity of the electrode and the overall ohmic resistance. This fundamental kinetic study will be used to understand the activity of the yeast as a catalyst in microbial half cell as well as fuel cell.

KeeSuk Nahm, Pil KIM

ECS Meeting Abstracts • 2014

Microbial fuel cells (MFCs) is one of the promising green energy sources to produce electricity from organic wastes with the help of bacteria as catalyst. It converts the chemical energy in organic wastes into electricity by bioelectrochemical reactions. In spite of the promise of MFCs, their applications are limited by low power generation efficiency. Power limitations can be addressed by the use of better suited anodes, and to modify the electrode surface with nanostructures is one of the ways to improve the efficiency of the anode. In this study, We have demonstrated MFCs performance based on Escherichia coli (E.coli) by optimizing the electrode surface structure using various nanomaterials like reduced grapheme oxide(rGO), graphite nanofiber(GNF) and carbon nanotube(CNT). Each of the nanomaterials is doped with iron particles of 3~10nm size, and were formed into a nanocomposite. The synthesized nanocomposites was assembled on the anode electrode surface by directly applying a magnetic field. This conductive multilayer of nanocomposites coated on anode enhances the electron transfer between the bacteria and the anode. The electrochemical activities with each catalysts of such as Fe/rGO, Fe/GNF and Fe/CNT are investigated by cyclic voltammetry, Impedance spectra and polarization curve measurements.

Léna Beauzamy, Jérôme Delacotte, Benjamin Bailleul et al.

bioRxiv (Cold Spring Harbor Laboratory) • 2020

ABSTRACT Microbial solar cells that mainly rely on the use of photosynthesic organisms are a promising alternative to photovoltaics for solar electricity production. In that way, we propose a new approach involving electrochemistry and fluorescence techniques. The coupled set-up Electro-Pulse-Amplitude-Modulation (“e-PAM”) enables the simultaneous recording of the produced photocurrent and fluorescence signals from the photosynthetic chain. This methodology was validated with a suspension of green alga Chlamydomonas reinhardtii in interaction with an exogenous redox mediatior (2,6-dichlorobenzoquinone; DCBQ). The balance between photosynthetic chain events (PSII photochemical yield, quenching) and the extracted electricity can be monitored overtime. More particularly, the non photochemical quenching induced by DCBQ mirrors the photocurrent. This set-up thus helps to distinguish the electron harvesting from some side effects due to quinones in real time. It therefore paves the way for future analyses devoted to the choice of the experimental conditions (redox mediator, photosynthetic organisms…) to find the best electron extraction.

M. Mawardi, W. S. Winanti, T. Sudinda et al.

IOP Conference Series: Earth and Environmental Science • 2023

The issue of global warming continues to be a concern for the international world. One of the causes of global warming is the greenhouse gas (GHG) effect caused by an increase in the amount of emissions in the atmosphere. Indonesia has set targets for reducing GHG emissions in the Nationally Determined Contribution (NDC) by 31.89% on its own capability and 43.20% with international assistance in 2030. Therefore, to support the program, it is necessary to conduct research to inventory the emissions produced and emissions absorbed by each region in Indonesia. This study calculated the net-zero emission index in an area by comparing the value of carbon emission with the value of carbon sequestration based on land cover in an area. Regional emission data was obtained from Aksara Bappenas, while regional sequestration data was obtained from RAD-GRK and satellite imagery interpretation based on land cover. Meanwhile, to calculate emissions at the city/regency level, individual carbon footprint data was used and converted into city/regency emission data. The calculation of the carbon index was carried out nationally in all provinces of Indonesia. Several provinces were further tested as examples to determine sequestration based on land cover from imagery interpretation. The results show that the Indonesian net-zero emission index is lower than 1, but some provinces with dense populations have a net-zero emission index >1, namely: DKI Jakarta, DI Yogyakarta, North Sumatra, and Riau.

A. Khan, Lizhen Huang

Energies • 2023

Due to an extensive usage of heavy machinery, the construction sector is criticized as one of the major CO2 emitters. To address climate concerns, mitigating these greenhouse gas (GHG) emissions is important. This study aimed to strategize for “zero emission construction” by assessing the life cycle environmental impacts of diesel, electric, and hybrid construction machinery. By applying life cycle assessment (LCA) principles with adherence to ISO 14040/44 methodologies, this study scrutinizes the environmental repercussions of a standard excavator over 9200 effective operational hours, from raw material acquisition to end-of-life disposal. The results demonstrate a significant reduction in global warming potential (GWP), ozone depletion potential (ODP), and acidification potential (AP) in transitioning from diesel to hybrid and fully electric machines. A nominal increase due to this shift also occurred and impacted categories such as human carcinogenic toxicity (HT), freshwater eutrophication (EP), and marine ecotoxicity (ME); however, a more significant upsurge was noted in terrestrial ecotoxicity (TE) due to battery production. Thus, this study highlights the need for a careful management of environmental trade-offs in the shift toward electrified machinery and the importance of centering on the environmental profile of the battery. Future work should focus on enhancing the environmental profile of battery production and disposal, with policy decisions encouraging holistic sustainability based on green energies in construction projects.

Qiao Yu, Brian Yueshuai He, Jiaqi Ma et al.

Nature Communications • 2023

Zero-emission vehicle (ZEV) adoption is a key climate mitigation tool, but its environmental justice implications remain unclear. Here, we quantify ZEV adoption at the census tract level in California from 2015 to 2020 and project it to 2035 when all new passenger vehicles sold are expected to be ZEVs. We then apply an integrated traffic model together with a dispersion model to simulate air quality changes near roads in the Greater Los Angeles. We found that per capita ZEV ownership in non-disadvantaged communities (non-DACs) as defined by the state of California is 3.8 times of that in DACs. Racial and ethnic minorities owned fewer ZEVs regardless of DAC designation. While DAC residents receive 40% more pollutant reduction than non-DACs due to intercommunity ZEV trips in 2020, they remain disproportionately exposed to higher levels of traffic-related air pollution. With more ZEVs in 2035, the exposure disparity narrows. However, to further reduce disparities, the focus must include trucks, emphasizing the need for targeted ZEV policies that address persistent pollution burdens among DAC and racial and ethnic minority residents.

Harshad Jathot

International Journal for Research in Applied Science and Engineering Technology • 2024

Abstract: With the rapid growth of digital services and the increasing reliance on data centers, energy consumption and carbon emissions from server infrastructure have become significant environmental concerns. This abstract outlines a novel approach for carbon detection from servers, aiming to improve the sustainability of data centers. Carbon emissions from data centers are increasingly a cause for concern, as the world grapples with the realities of climate change. According to recent studies, data centers are responsible for a significant share of global electricity consumption, and subsequently, carbon emissions. It’s evident that addressing the sustainability of data centers is not just a technological challenge; it’s a moral and environmental imperative.

Patrick Fortin

ECS Meeting Abstracts • 2022

The overall aim of this project is to establish a generic modelling platform for the design and operation of zero-emission MW-scale hybrid electric energy systems, with a particular focus on maritime transport applications. The project seeks to integrate battery and fuel cell degradation models with operating strategy models to minimize the total cost of ownership (TCO) of hybrid battery/fuel cell systems. The modelling approach used here, to simulate battery and fuel cell degradation, takes advantage of empirical modelling methods already established in the scientific literature. This approach offers three distinct advantages over alternative multi-physics models, in that empirical degradation models are (i) computationally efficient, (ii) can be integrated into other modelling frameworks, and (iii) can support the quick parameterization of different systems. Real-life battery and fuel cell degradation data, collected using state-of-the-art materials, was used to quantify the model parameters and validate the proposed degradation models. A variety of advanced in-situ electrochemical characterization methods have been employed to quantify the relevant parameters at the beginning-of-life and again after various stages of ageing to determine degradation rates of the relevant parameters. The second aspect of this project is the implementation of a technoeconomic optimization model that combines the data-driven degradation models with additional inputs such as operating conditions, operational profile (i.e., drive cycle), cost of hydrogen, cost of electricity, etc. to design optimal hybrid battery/fuel cell systems and determine optimal control strategies to minimize degradation and total cost of ownership over the system lifetime. This talk will focus on the advanced in-situ electrochemical techniques that have been used to extract fuel cell degradation parameters and provide an overview of both the empirical degradation and technoeconomical models. Finally, we will present the optimization results obtained using our platform for the implementation of a hybrid energy system in a coastal Norwegian ferry.

Jing-yu Ran, Chang-lei Qin

ASME 2010 Power Conference • 2010

CO2 is a main greenhouse gas fazing the Earth. So countries around the world are actively studying the methods of capturing CO2 to reduce emission. In this paper, firstly a brief review was carried out on the research development and technical problems of three typical near-zero CO2 emission power generation systems. Focus was made on the construction of one possible commercially applied zero emission system, which has new principle but relatively conservative sections. Preliminary analysis and calculation of energy and mass flow have been finished to evaluate its performance. The results showed that apart from zero CO2 emission, a relatively tempting efficiency could be sustained. Theoretically, higher than 90% purity of CO2 and 63% generation efficiency of the whole system can be achieved.