Self-Powered Biosensors

Self-powered electrochemical biosensors utilize biofuel cells as a simultaneous power source and biosensor, which simplifies the biosensor system, because it no longer requires a potentiostat, power for the potentiostat, and/or power for the signaling device. This review article is focused on detailing the advances in the field of self-powered biosensors and discussing their advantages and limitations compared to other types of electrochemical biosensors. The review will discuss self-powered biosensors formed from enzymatic biofuel cells, organelle-based biofuel cells, and microbial fuel cells. It also discusses the different mechanisms of sensing, including utilizing the analyte being the substrate/fuel for the biocatalyst, the analyte binding the biocatalyst to the electrode surface, the analyte being an inhibitor of the biocatalyst, the analyte resulting in the blocking of the bioelectrocatalytic response, the analyte reactivating the biocatalyst, Boolean logic gates, and combining affinity-based biorecognition elements with bioelectrocatalytic power generation. The final section of this review details areas of future investigation that are needed in the field, as well as problems that still need to be addressed by the field

Rational design of artificial redox-mediating systems toward upgrading photobioelectrocatalysis

Photobioelectrocatalysis has recently attracted particular research interest owing to the possibility to achieve sunlight-driven biosynthesis, biosensing, power generation, and other niche applications. However, physiological incompatibilities between biohybrid components lead to poor electrical contact at the biotic-biotic and biotic-abiotic interfaces. Establishing an electrochemical communication between these different interfaces, particularly the biocatalyst-electrode interface, is critical for the performance of the photobioelectrocatalytic system. While different artificial redox mediating approaches spanning across interdisciplinary research fields have been developed in order to electrically wire biohybrid components during bioelectrocatalysis, a systematic understanding on physicochemical modulation of artificial redox mediators is further required. Herein, we review and discuss the use of diffusible redox mediators and redox polymer-based approaches in artificial redox-mediating systems, with a focus on photobioelectrocatalysis. The future possibilities of artificial redox mediator system designs are also discussed within the purview of present needs and existing research breadth

Hypersaline microbial self-powered biosensor with increased sensitivity

The on-line, self-powered monitoring of the organic carbon content in hypersaline solutions (e.g. chemical oxygen demand, COD) based on a microbial biosensor would avoid the generation of toxic waste, originated by common COD analytical methods, and reduce the release of pollutants into the environment. Herein, a disposable cathode was applied to microbial fuel cells (MFCs) for the environmental friendly monitoring of the COD reaching a sensitivity one order of magnitude higher compared to the MFC with an air breathing cathode. Additionally, the entrapment of bacterial cells in alginate-capsules ensured a considerable linear range (up to approximately 10,000 mg COD L−1), providing opportunities for the wide application of the device to hypersaline solutions characterized by different origins and contamination levels

Editors' Choice-Review-Exploration of Computational Approaches for Understanding Microbial Electrochemical Systems: Opportunities and Future Directions

Microbial electrochemical systems offer valuable opportunities in the field of electrochemistry for a wide range of applications and fundamental insights. Applications include renewable power generation, electrosynthesis, and sensing, and provide a critical platform for understanding fundamental electrochemical processes between biotic and abiotic components. However, despite several research efforts, the fundamental electron transfer mechanisms inherent to microbial bioelectrochemical systems remain poorly understood, limiting their full potential and applications. This lack of fundamental understanding stems from both the conceptual and experimental complexity of microbial electrochemical systems. In this context, the possibility of multi-disciplinary research utilizing computational methods provides a powerful tool for this field. Herein, we critically review how computational studies and methods employed to study microbial electrochemical systems in multiple dimensions can be used to clarify the different factors governing microbial electrochemical systems. This discussion addresses how the combination of various techniques can enhance fundamental understanding, providing scientists with tools for the rational design of improved systems and opening exciting new research opportunities

Realization of an Asymmetric Non‐Aqueous Redox Flow Battery through Molecular Design to Minimize Active Species Crossover and Decomposition

This communication presents a mechanism‐based approach to identify organic electrolytes for non‐aqueous redox flow batteries (RFBs). Symmetrical flow cell cycling of a pyridinium anolyte and a cyclopropenium catholyte resulted in extensive capacity fade due to competing decomposition of the pyridinium species. Characterization of this decomposition pathway enabled the rational design of next‐generation anolyte/catholyte pairs with dramatically enhanced cycling performance. Three factors were identified as critical for slowing capacity fade: (1) separating the anolyte–catholyte in an asymmetric flow cell using an anion exchange membrane (AEM); (2) moving from monomeric to oligomeric electrolytes to limit crossover through the AEM; and (3) removing the basic carbonyl moiety from the anolyte to slow the protonation‐induced decomposition pathway. Ultimately, these modifications led to a novel anolyte–catholyte pair that can be cycled in an AEM‐separated asymmetric RFB for 96 h with >95 % capacity retention at an open circuit voltage of 1.57 V.Applied molecular design! This study presents a mechanism‐based approach to the molecular design of electrolytes for implementation in an asymmetric non‐aqueous redox flow battery.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154972/1/chem202000749-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154972/2/chem202000749.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154972/3/chem202000749_am.pd

An engineered, non-diazotrophic cyanobacterium and its application in bioelectrochemical nitrogen fixation

The reduction of chemically inert nitrogen to ammonia is a critical step in the global nitrogen cycle. Microbial nitrogen fixation is a promising way to realize nitrogen reduction and ammonia production at mild conditions. Here, we report an engineered, non-diazotrophic Synechococcus elongatus PCC 7942 strain with nitrogen fixation activity that is constructed by integrating a modified nitrogenase gene cluster into the genome. The engineered S. elongatus PCC 7942 strain is employed in a bioelectrochemical nitrogen-fixation (e-BNF) system for ammonia production. Because the e-BNF system supplies adequate external electrons for the turnover of nitrogenase, the nitrogen fixation activity of the engineered S. elongatus PCC 7942 strain is significantly improved. After 48 h of reaction, the e-BNF system accumulates 173 μM of NH3, which is 21 times higher than that generated from solely photosynthesis-driven nitrogen fixation, with faradaic efficiency of 6.85%. This work may provide new insight into biological nitrogen-fixation systems and ammonium production

Recent trends and advances in microbial electrochemical sensing technologies: An overview

Microbial electrochemical systems utilize the electrochemical interaction between microorganisms and electrode surfaces to convert chemical energy into electrical energy, offering a promise as technologies for wastewater treatment, bioremediation, and biofuel production. Recently, growing research attention has been devoted to the development of microbial electrochemical sensrs as biosensing platforms. Microbial electrochemical sensors are a type of microbial electrochemical technology (MET) capable of sensing through the anodic or the cathodic electroactive microorganisms and/or biofilms. Herein, we review and summarize the recent advances in the design of microbial electrochemical sensing approaches with a specific overview and discussion of anodic and cathodic microbial electrochemical sensor devices, highlighting both the advantages and disadvantages. Particular emphasis is given on the current trends and strategies in the design of low-cost, convenient, efficient, and high performing METs with different biosensing applications, including toxicity monitoring, pathogen detection, corrosion monitoring, as well as measurements of biological oxygen demand, chemical oxygen demand, and dissolved oxygen. The conclusion provides perspectives and an outlook to understand the shortcomings in the design, development status, and sensing applications of microbial electrochemical platforms. Namely, we discuss key challenges that limit the practical implementation of METs for sensing purposes and deliberate potential solutions, necessary developments, and improvements in the field

Deliberating Animal Values: a Pragmatic-Pluralistic Approach to Animal Ethics.

Debates in animal ethics are largely characterized by ethical monism, the search for a single, timeless, and essential trait in which the moral standing of animals can be grounded. In this paper, we argue that a monistic approach towards animal ethics hampers and oversimplifies the moral debate. The value pluralism present in our contemporary societies requires a more open and flexible approach to moral inquiry. This paper advocates the turn to a pragmatic, pluralistic approach to animal ethics. It contributes to the development of such an approach in two ways. It offers a pragmatist critique of ethical monism in animal ethics and presents the results of a qualitative study into the value diversity present in the different ways of thinking about animals in the Netherlands. Carefully arranged group discussions resulted in the reconstruction of four distinctive moral value frameworks that may serve as instruments in the future process of moral inquiry and deliberation in the reflection on animal use. © 2010 The Author(s)

Bioelectrical understanding and engineering of cell biology

The last five decades of molecular and systems biology research have provided unprecedented insights into the molecular and genetic basis of many cellular processes. Despite these insights, however, it is arguable that there is still only limited predictive understanding of cell behaviours. In particular, the basis of heterogeneity in single-cell behaviour and the initiation of many different metabolic, transcriptional or mechanical responses to environmental stimuli remain largely unexplained. To go beyond the status quo, the understanding of cell behaviours emerging from molecular genetics must be complemented with physical and physiological ones, focusing on the intracellular and extracellular conditions within and around cells. Here, we argue that such a combination of genetics, physics and physiology can be grounded on a bioelectrical conceptualization of cells. We motivate the reasoning behind such a proposal and describe examples where a bioelectrical view has been shown to, or can, provide predictive biological understanding. In addition, we discuss how this view opens up novel ways to control cell behaviours by electrical and electrochemical means, setting the stage for the emergence of bioelectrical engineering

Compassion as a practical and evolved ethic for conservation

© The Author(s) 2015. Published by Oxford University Press on behalf of the American Institute of Biological Sciences. The ethical position underpinning decisionmaking is an important concern for conservation biologists when setting priorities for interventions. The recent debate on how best to protect nature has centered on contrasting intrinsic and aesthetic values against utilitarian and economic values, driven by an inevitable global rise in conservation conflicts. These discussions have primarily been targeted at species and ecosystems for success, without explicitly expressing concern for the intrinsic value and welfare of individual animals. In part, this is because animal welfare has historically been thought of as an impediment to conservation. However, practical implementations of conservation that provide good welfare outcomes for individuals are no longer conceptually challenging; they have become reality. This reality, included under the auspices of "compassionate conservation," reflects an evolved ethic for sharing space with nature and is a major step forward for conservation