22 research outputs found
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Real-time monitoring of the dynamic metabolism and responses of pathogenic bacteria using electroanalytical methods
No full textMicrobial infections remain the leading cause of increased morbidity and mortality rates of patients suffering from infectious diseases. While thousands of pathogenic bacteria have been recognized, the majority of healthcare-associated infections are caused by only a few opportunistic pathogens (e.g., Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli), which are associated with increased antibiotic resistance. The rapid detection, reliable identification and real-time monitoring of these pathogens remain not only a scientific problem but also a practical challenge of vast importance, especially in tailoring effective treatment strategies. Various approaches, such as conventional culturing, molecular methods and mass spectrometry techniques, have been employed to identify and quantify pathogenic agents. Yet, these procedures are costly, time-consuming, mostly qualitative, and are indirect detection methods. A great challenge is therefore to develop rapid and quantitative methods for the detection of microbes. As an alternative, electrochemical techniques have been explored as a means for the detection of infection-related biomarkers. This thesis presents the development and application of a robust electrochemical platform using transparent carbon ultramicroelectrode arrays (T-CUAs) for the in vitro detection of bacterial warfare toxin, pyocyanin, and other phenazine metabolites produced by P. aeruginosa. This antibiotic-resistant pathogen is commonly found in chronic wounds and the lungs of cystic fibrosis patients. During early infection stages, P. aeruginosa produces various phenazines as virulence factors, which are highly diffusible signals that are toxic to surrounding host cells and other competing microorganisms. Although phenazines play important roles in cellular functions, very little is known about how their concentrations fluctuate and influence cellular behaviors and population-dependent responses (quorum sensing) during infection and growth. Therefore, quantitative, real-time electrochemical monitoring of distinct redox-active phenazine metabolites from P. aeruginosa in simulated growth media is demonstrated using T-CUAs. Moreover, electrochemical monitoring of the influence of polymicrobial infections on P. aeruginosa phenazine production is presented. In addition to quantifying phenazine concentrations in complex environments, changes in phenazine dynamics are observed in the biosynthetic route for pyocyanin production. Finally, desorption electrospray ionization and nanoelectrospray ionization mass spectrometry are used to identify phenazines observed with our electrochemical devicesChemistr
Fundamentals, Applications, and Future Directions of Bioelectrocatalysis
No full textBioelectrocatalysis is an interdisciplinary research field combining bio-catalysis and electrocatalysis via the utilization of materials derived from biological systems as catalysts to catalyze the redox reactions occurring at an electrode. Bioelectrocatalysis synergistically couples the merits of both biocatalysis and electrocatalysis. The advantages of biocatalysis include high activity, high selectivity, wide substrate scope, and mild reaction conditions. The advantages of electrocatalysis include the possible utilization of renewable electricity as an electron source and high energy conversion efficiency. These properties are integrated to achieve selective biosensing, efficient energy conversion, and the production of
diverse products. This review seeks to systematically and comprehensively detail the fundamentals, analyze the existing problems, summarize the development status and applications, and look toward the future development directions of bioelectrocatalysis. First, the structure, function, and modification of bioelectrocatalysts are discussed. Second, the essentials of bioelectrocatalytic systems, including electron transfer mechanisms, electrode materials, and reaction medium, are described. Third, the application of bioelectrocatalysis in the fields of biosensors, fuel cells, solar cells, catalytic mechanism studies, and bioelectrosyntheses of high-value chemicals are systematically summarized. Finally, future developments and a perspective on bioelectrocatalysis are suggested
Deconvoluting Charge Transfer Mechanisms in Conducting Redox Polymer-Based Photobioelectrocatalytic Systems
No full textPoor electrochemical communication between biocatalysts and electrodes is a ubiquitous limitation to bioelectrocatalysis efficiency. An extensive library of polymers has been developed to modify biocatalyst-electrode interfaces to alleviate this limitation. As such, conducting redox polymers (CRPs) are a versatile tool with high structural and functional tunability. While charge transport in CRPs is well characterized, the understanding of charge transport mechanisms facilitated by CRPs within decisively complex photobioelectrocatalytic systems remains very limited. This study is a comprehensive analysis that dissects the complex kinetics of photobioelectrodes into fundamental blocks based on rational assumptions, providing a mechanistic overview of charge transfer during photobioelectrocatalysis. We quantitatively compare two biohybrids of metal-free unbranched CRP (polydihydroxy aniline) and photobiocatalyst (intact chloroplasts), formed utilizing two deposition strategies (“mixed” and “layered” depositions). The superior photobioelectrocatalytic performance of the “layered” biohybrid compared to the “mixed” counterpart is justified in terms of rate (D
app), thermodynamic and kinetic barriers (H≠, E
a), frequency of molecular collisions (D
0) during electron transport across depositions, and rate and resistance to heterogeneous electron transfer (k
0, R
CT). Our results indicate that the primary electron transfer mechanism across the biohybrids, constituting the unbranched CRP, is thermally activated intra- and inter-molecular electron hopping, as opposed to a non-thermally activated polaron transfer model typical for branched CRP- or conducting polymer (CP)-containing biohybrids in literature. This work underscores the significance of subtle interplay between CRP structure and deposition strategy in tuning the polymer-catalyst interfaces, and the branched/unbranched structural classification of CRPs in the bioelectrocatalysis context.</jats:p
KONSTANTIN MILADINOVS SEHNSUCHT NACH DEM SÜDEN (T’GA ZA JUG) IM INTERKULTURELLEN ÜBERSETZUNGSVERGLEICH
No full textComing from Struga, the frail and gentle Konstantin Miladinov is overcome by grim feelings of coldness, gloom and loneliness, which are his constant companions during his studies in Moscow. It is these dark and dreary feelings that nurture his yearning for the warm sunshine of the South. By exclusively using positive epithets to depict the native soil, the author evokes the painful, unattainable desire to return to his homeland, symbiotically embracing it. This longing for the homeland culminates in a singular, heavenly exaltation for which it is worth losing one’s life.
Forming a part of Macedonia’s literary cultural heritage, the poem “Longing for the South” by K. Miladinov is above all, the cornerstone of contemporary Macedonian poetry, and as such has been verse translated into 60 languages. In our article, we focus on the comparison between the verse translations of the poem into English, German, French, Serbian and Croatian. The comparison highlights the cultural specificities and their intercultural reflections.Kälte, Finsternis und Einsamkeit während des Studiums in Moskau evozieren bei dem kränklichen Konstantin Miladinov aus Struga die Sehnsucht nach Wärme, Sonne und Geborgenheit. Epitheta, die für den Autor ausschlieβlich in der Heimat verwurzelt sind, und so den schmerzhaften Wunsch nach Heimkehr und symbiotischer Konnexion mit ihr zu einem singulären, göttlichen Erlebnis kulminieren lassen, für das es sich lohnt, aus dem Leben zu scheiden.
Miladinovs T’ga za jug, Kulturerbe Mazedoniens und Grundstein der mazedonischen zeitgenössischen Lyrik, liegt in 60 Nachdichtungen vor und wird in diesem Beitrag im interkulturellen Übersetzungsvergleich in deutscher, englischer, französischer, serbischer und kroatischer Version beleuchtet. Im Vordergrund liegen Kulturspezifika und ihre interlinguale Versprachlichung
The Use of Electroactive Halophilic Bacteria for Improvements and Advancements in Environmental High Saline Biosensing
No full textHalophilic bacteria are remarkable organisms that have evolved strategies to survive in high saline concentrations. These bacteria offer many advances for microbial-based biotechnologies and are commonly used for industrial processes such as compatible solute synthesis, biofuel production, and other microbial processes that occur in high saline environments. Using halophilic bacteria in electrochemical systems offers enhanced stability and applications in extreme environments where common electroactive microorganisms would not survive. Incorporating halophilic bacteria into microbial fuel cells has become of particular interest for renewable energy generation and self-powered biosensing since many wastewaters can contain fluctuating and high saline concentrations. In this perspective, we highlight the evolutionary mechanisms of halophilic microorganisms, review their application in microbial electrochemical sensing, and offer future perspectives and directions in using halophilic electroactive microorganisms for high saline biosensing
Fundamentals and Applications of Enzymatic Bioelectrocatalysis
No full textBioelectrocatalysis is a major cross-disciplinary sub-field of electrocatalysis, which couples the advantages of biocatalysis and electrocatalysis. Bioelectrocatalysis utilized biologically-derived materials as biocatalysis to catalyze oxidation-reduction (redox) reactions on conductive electrode surfaces. This chapter will focus and detail the fundamental aspects and applications of enzymatic bioelectrocatalysis where isolated oxidoreductases are commonly used as a biocatalyst. the central concepts of the electrochemistry of redox enzymes, structure, function, and enzyme engineering strategies will be described. the chapter will also summarize the mechanisms of electron transfer, electrode materials, and electrode-biocatalysis electrical connections. Finally, this chapter will discuss the three main applications of enzymatic bioelectrocatalysis, specifically electrochemical biosensor devices, fuel cells, and bioelectrosynthetic systems
Unbranched Hybrid Conducting Redox Polymers for Intact Chloroplast-Based Photobioelectrocatalysis
No full textRecent trends and advances in microbial electrochemical sensing technologies: An overview
No full textPhenazine-Based Compound as a Universal Water-Soluble Anolyte Material for the Redox Flow Batteries
No full textAqueous organic redox flow batteries (AORFBs) are emerging energy storage technologies due to their high availability, low cost of organic compounds, and the use of eco-friendly water-based supporting electrolytes. In the present work, we demonstrate a unique phenazine-based material that shows redox reversibility in neutral, basic, and acidic conditions with the redox potentials of −0.85 V (1.0 M KOH), −0.67 V (1.0 M NaCl), −0.26 V, and 0.05 V (1.0 M H2SO4) vs. the Ag/AgCl reference electrode and two-electron transfer process at all pH values. High solubility of the phenazine compound in water-based electrolytes up to 1.3 M is achieved by introducing quaternary amonium-based substituents, leading to the outstanding theoretical volumetric capacity of 70 Ah L−1. Laboratory redox flow batteries in neutral and acidic electrolytes presented >100 cycles of stable operation with a capacity loss of 0.25 mAh L−1 and 1.29 mAh L−1 per cycle, respectively. The obtained results demonstrate a material with the potential for not only fundamental understanding but also the practical application of AORFBs in the development of new-generation energy storage technologies
