Publications by authors named "Shelley D Minteer"

171 Publications

One-Pot Bioelectrocatalytic Conversion of Chemically Inert Hydrocarbons to Imines.

J Am Chem Soc 2022 Jan 25. Epub 2022 Jan 25.

Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States.

Petroleum hydrocarbons are our major energy source and an important feedstock for the chemical industry. With the exception of combustion, the deep conversion of chemically inert hydrocarbons to more valuable chemicals is of considerable interest. However, two challenges hinder this conversion. One is the regioselective activation of inert carbon-hydrogen (C-H) bonds. The other is designing a pathway to realize this complicated conversion. In response to the two challenges, a multistep bioelectrocatalytic system was developed to realize the one-pot deep conversion from heptane to -heptylhepan-1-imine under mild conditions. First, in this enzymatic cascade, a bioelectrocatalytic C-H bond oxyfunctionalization step based on alkane hydroxylase (alkB) was applied to regioselectively convert heptane to 1-heptanol. By integrating subsequent alcohol oxidation and bioelectrocatalytic reductive amination steps based on an engineered choline oxidase (AcCO) and a reductive aminase (NfRedAm), the generated 1-heptanol was successfully converted to -heptylhepan-1-imine. The electrochemical architecture provided sufficient electrons to drive the bioelectrocatalytic C-H bond oxyfunctionalization and reductive amination steps with neutral red (NR) as electron mediator. The highest concentration of -heptylhepan-1-imine achieved was 0.67 mM with a Faradaic efficiency of 45% for C-H bond oxyfunctionalization and 70% for reductive amination. Hexane, octane, and ethylbenzene were also successfully converted to the corresponding imines. Via regioselective C-H bond oxyfunctionalization, intermediate oxidation, and reductive amination, the bioelectrocatalytic hydrocarbon deep conversion system successfully realized the challenging conversion from inert hydrocarbons to imines that would have been impossible by using organic synthesis methods and provided a new methodology for the comprehensive conversion and utilization of inert hydrocarbons.
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http://dx.doi.org/10.1021/jacs.1c13063DOI Listing
January 2022

Nanopore-based measurement of the interaction of P450cam monooxygenase and putidaredoxin at the single-molecule level.

Faraday Discuss 2021 Dec 10. Epub 2021 Dec 10.

State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, China.

Protein-protein interactions occur in a wide range of biological processes and are of great significance to life function. Characterization of transient protein-protein interactions remains a significant barrier to our understanding of cellular processes. Nanopores provide unique nanoscale environments that accommodate single molecules from the surrounding bulk solution. This method permits label-free sensing at the single-molecule level with extremely high sensitivity. Herein, the interaction between a single P450cam monooxygenase and its redox partner putidaredoxin (Pdx) was monitored transient ionic current by using functionalized glass nanopores. Results show that the volume of P450cam determines the blockage current while the interactions between the P450cam and Pdx give a long blockage duration. Our glass nanopore sensor with adjustable diameter could be applied for real-time sensing of protein-protein interactions between individual proteins with a wide range of molecular weight.
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http://dx.doi.org/10.1039/d1fd00042jDOI Listing
December 2021

Advances on the Merger of Electrochemistry and Transition Metal Catalysis for Organic Synthesis.

Chem Rev 2021 Nov 19. Epub 2021 Nov 19.

Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States.

Synthetic organic electrosynthesis has grown in the past few decades by achieving many valuable transformations for synthetic chemists. Although electrocatalysis has been popular for improving selectivity and efficiency in a wide variety of energy-related applications, in the last two decades, there has been much interest in electrocatalysis to develop conceptually novel transformations, selective functionalization, and sustainable reactions. This review discusses recent advances in the combination of electrochemistry and homogeneous transition-metal catalysis for organic synthesis. The enabling transformations, synthetic applications, and mechanistic studies are presented alongside advantages as well as future directions to address the challenges of metal-catalyzed electrosynthesis.
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http://dx.doi.org/10.1021/acs.chemrev.1c00614DOI Listing
November 2021

Materials Approaches for Improving Electrochemical Sensor Performance.

J Phys Chem B 2021 11 22;125(43):11820-11834. Epub 2021 Oct 22.

Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States.

Electrochemical sensors have emerged as important diagnostic tools in recent years, due to their simplicity and ease of use. Compared to instrumental analysis methods that use complicated experimental and data analysis techniques─such as mass spectrometry, nuclear magnetic resonance (NMR), spectrophotometric methods, and chromatography─electrochemical sensors show promise for use in a wide range of real-time and applications such as pharmaceutical testing, environmental monitoring, and medical diagnostics. In order to identify analytes in complex and/or biological samples, materials used for both the electrode materials and the chemically selective layer have been evolving throughout the years for optimizing the analytical performance of electrochemical sensors to increase sensitivity, selectivity and linear range. In this Perspective, attention will be focused on different types of materials that have been used for electrochemical sensing, including new combinations of well-studied materials as well as novel strategies to enhance the performance of sensing devices. The Perspective will also discuss existing challenges in the field and future strategies for addressing those challenges.
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http://dx.doi.org/10.1021/acs.jpcb.1c07063DOI Listing
November 2021

Rational design of artificial redox-mediating systems toward upgrading photobioelectrocatalysis.

Photochem Photobiol Sci 2021 Oct 22;20(10):1333-1356. Epub 2021 Sep 22.

Department of Chemistry, University of Utah, Salt Lake City, UT, 84112, USA.

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.
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http://dx.doi.org/10.1007/s43630-021-00099-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8455808PMC
October 2021

A silver assist for microbial fuel cell power.

Science 2021 09 16;373(6561):1308-1309. Epub 2021 Sep 16.

Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA.

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http://dx.doi.org/10.1126/science.abl3612DOI Listing
September 2021

Using structure-function relationships to understand the mechanism of phenazine-mediated extracellular electron transfer in .

iScience 2021 Sep 25;24(9):103033. Epub 2021 Aug 25.

Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA.

Phenazines are redox-active nitrogen-containing heterocyclic compounds that can be produced by either bacteria or synthetic approaches. As an electron shuttles (mediators), phenazines are involved in several biological processes facilitating extracellular electron transfer (EET). Therefore, it is of great importance to understand the structural and electronic properties of phenazines that promote EET in microbial electrochemical systems. Our previous study experimentally investigated a phenazine-based library as an exogenous mediator system to facilitate EET in . Herein, we combine our experimental data with density functional theory (DFT) calculations and multivariate linear regression modeling to understand the structure-function relationships in phenazine-based mediated EET. These calculations demonstrate that the computed redox properties of phenazines in lipophilic environments (e.g., cell membrane) correlate to experimental mediated current densities. Additional DFT-derived molecular properties were considered to develop a predictive model, which could be used in metabolic engineering approaches to introduce phenazines as endogenous mediators into bacteria.
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http://dx.doi.org/10.1016/j.isci.2021.103033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8426270PMC
September 2021

Substrate Channeling by a Rationally Designed Fusion Protein in a Biocatalytic Cascade.

JACS Au 2021 Aug 1;1(8):1187-1197. Epub 2021 Jul 1.

Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States.

Substrate channeling, where an intermediate in a multistep reaction is directed toward a reaction center rather than freely diffusing, offers several advantages when employed in catalytic cascades. Here we present a fusion enzyme comprised of an alcohol and aldehyde dehydrogenase, that is computationally designed to facilitate electrostatic substrate channeling using a cationic linker bridging the two structures. Rosetta protein folding software was utilized to determine an optimal linker placement, added to the truncated termini of the proteins, which is as close as possible to the active sites of the enzymes without disrupting critical catalytic residues. With improvements in stability, product selectivity (90%), and catalyst turnover frequency, representing 500-fold increased activity compared to the unbound enzymes and nearly 140-fold for a neutral-linked fusion enzyme, this design strategy holds promise for making other multistep catalytic processes more sustainable and efficient.
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http://dx.doi.org/10.1021/jacsau.1c00180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8397353PMC
August 2021

Mechanical studies of the solid electrolyte interphase on anodes in lithium and lithium ion batteries.

Nanotechnology 2021 Sep 27;32(50). Epub 2021 Sep 27.

Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, UT 84112, United States of America.

A stable solid electrolyte interphase (SEI) layer is key to high performing lithium ion and lithium metal batteries for metrics such as calendar and cycle life. The SEI must be mechanically robust to withstand large volumetric changes in anode materials such as lithium and silicon, so understanding the mechanical properties and behavior of the SEI is essential for the rational design of artificial SEI and anode form factors. The mechanical properties and mechanical failure of the SEI are challenging to study, because the SEI is thin at only ~10-200 nm thick and is air sensitive. Furthermore, the SEI changes as a function of electrode material, electrolyte and additives, temperature, potential, and formation protocols. A variety ofandtechniques have been used to study the mechanics of the SEI on a variety of lithium ion battery anode candidates; however, there has not been a succinct review of the findings thus far. Because of the difficulty of isolating the true SEI and its mechanical properties, there have been a limited number of studies that can fully de-convolute the SEI from the anode it forms on. A review of past research will be helpful for culminating current knowledge and helping to inspire new innovations to better quantify and understand the mechanical behavior of the SEI. This review will summarize the different experimental and theoretical techniques used to study the mechanics of SEI on common lithium battery anodes and their strengths and weaknesses.
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http://dx.doi.org/10.1088/1361-6528/ac17feDOI Listing
September 2021

Advances in electrochemical cofactor regeneration: enzymatic and non-enzymatic approaches.

Curr Opin Biotechnol 2021 Jul 8;73:14-21. Epub 2021 Jul 8.

Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, UT 84112, USA. Electronic address:

Nicotinamide adenine dinucleotide(NAD(P)H) is a metabolically interconnected redox cofactor serving as a hydride source for the majority of oxidoreductases, and consequently constituting a significant cost factor for bioprocessing. Much research has been devoted to the development of efficient, affordable, and sustainable methods for the regeneration of these cofactors through chemical, electrochemical, and photochemical approaches. However, the enzymatic approach using formate dehydrogenase is still the most abundantly employed in industrial applications, even though it suffers from system complexity and product purity issues. In this review, we summarize non-enzymatic and enzymatic electrochemical approaches for cofactor regeneration, then discuss recent developments to solve major issues. Issues discussed include Rh-catalyst mediated enzyme mutual inactivation, electron-transfer rates, catalyst sustainability, product selectivity and simplifying product purification. Recently reported remedies are discussed, such as heterogeneous metal catalysts generating H as the sole byproduct or high activity and stability redox-polymer immobilized enzymatic systems for sustainable organic synthesis.
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http://dx.doi.org/10.1016/j.copbio.2021.06.013DOI Listing
July 2021

Analyzing mechanisms in Co(i) redox catalysis using a pattern recognition platform.

Chem Sci 2021 Feb 17;12(13):4771-4778. Epub 2021 Feb 17.

Department of Chemistry, University of Utah 315 South 1400 East Salt Lake City Utah 84112 USA

Redox catalysis has been broadly utilized in electrochemical synthesis due to its kinetic advantages over direct electrolysis. The appropriate choice of redox mediator can avoid electrode passivation and overpotential, which strongly inhibit the efficient activation of substrates in electrolysis. Despite the benefits brought by redox catalysis, establishing the precise nature of substrate activation remains challenging. Herein, we determine that a Co(i) complex bearing two ,,-tridentate ligands acts as a competent redox catalyst for the reduction of benzyl bromide substrates. Kinetic studies combining electroanalytical techniques with multivariable linear-regression analysis were conducted, disclosing an outer-sphere electron-transfer mechanism, which occurs in concert with C-Br bond cleavage. Furthermore, we apply a pattern recognition platform to distinguish between mechanisms in the activation of benzyl bromides, found to be dependent on the ligation state of the cobalt(i) center and ligand used.
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http://dx.doi.org/10.1039/d0sc06725cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8179645PMC
February 2021

Unbranched Hybrid Conducting Redox Polymers for Intact Chloroplast-Based Photobioelectrocatalysis.

Langmuir 2021 Jun 16. Epub 2021 Jun 16.

Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.

Photobioelectrocatalysis (PBEC) adopts the sophistication and sustainability of photosynthetic units to convert solar energy into electrical energy. However, the electrically insulating outer membranes of photosynthetic units hinder efficient extracellular electron transfer from photosynthetic redox centers to an electrode in photobioelectrocatalytic systems. Among the artificial redox-mediating approaches used to enhance electrochemical communication at this biohybrid interface, conducting redox polymers (CRPs) are characterized by high intrinsic electric conductivities for efficient charge transfer. A majority of these CRPs constitute peripheral redox pendants attached to a conducting backbone by a linker. The consequently branched CRPs necessitate maintaining synergistic interactions between the pendant, linker, and backbone for optimal mediator performance. Herein, an unbranched, metal-free CRP, polydihydroxy aniline (PDHA), which has its redox moiety embedded in the polymer mainchain, is used as an exogenous redox mediator and an immobilization matrix at the biohybrid interface. As a proof of concept, the relatively complex membrane system of spinach chloroplasts is used as the photobioelectrocatalyst of choice. A "mixed" deposition of chloroplasts and PDHA generated a 2.4-fold photocurrent density increment. An alternative "layered" PDHA-chloroplast deposition, which was used to control panchromatic light absorbance by the intensely colored PDHA competing with the photoactivity of chloroplasts, generated a 4.2-fold photocurrent density increment. The highest photocurrent density recorded with intact chloroplasts was achieved by the "layered" deposition when used in conjunction with the diffusible redox mediator 2,6-dichlorobenzoquinone (-48 ± 3 μA cm). Our study effectively expands the scope of germane CRPs in PBEC, emphasizing the significance of the rational selection of CRPs for electrically insulating photobioelectrocatalysts and of the holistic modulation of the CRP-mediated biohybrids for optimal performance.
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http://dx.doi.org/10.1021/acs.langmuir.1c01167DOI Listing
June 2021

-Ammonium Ylide Mediators for Electrochemical C-H Oxidation.

J Am Chem Soc 2021 05 13;143(20):7859-7867. Epub 2021 May 13.

Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.

The site-specific oxidation of strong C(sp)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial circles. One main drawback of current chemical reagents is the lack of diversity with regard to structure and reactivity that prevents a combinatorial approach for rapid screening to be employed. In that regard, directed evolution still holds the greatest promise for achieving complex C-H oxidations in a variety of complex settings. Herein we present a rationally designed platform that provides a step toward this challenge using -ammonium ylides as electrochemically driven oxidants for site-specific, chemoselective C(sp)-H oxidation. By taking a first-principles approach guided by computation, these new mediators were identified and rapidly expanded into a library using ubiquitous building blocks and trivial synthesis techniques. The ylide-based approach to C-H oxidation exhibits tunable selectivity that is often exclusive to this class of oxidants and can be applied to real-world problems in the agricultural and pharmaceutical sectors.
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http://dx.doi.org/10.1021/jacs.1c03780DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8718116PMC
May 2021

The Use of Electroactive Halophilic Bacteria for Improvements and Advancements in Environmental High Saline Biosensing.

Biosensors (Basel) 2021 Feb 12;11(2). Epub 2021 Feb 12.

Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA.

Halophilic 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.
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http://dx.doi.org/10.3390/bios11020048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7917972PMC
February 2021

Rapid Entrapment of Phenazine Ethosulfate within a Polyelectrolyte Complex on Electrodes for Efficient NAD Regeneration in Mediated NAD-Dependent Bioelectrocatalysis.

ACS Appl Mater Interfaces 2021 Mar 1;13(9):10942-10951. Epub 2021 Mar 1.

Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.

Over the past two decades, the designs of redox polymers have become critical to the field of mediated bioelectrocatalysis and are used in commercial glucose biosensors, as well as other bioelectrochemical applications (e.g., energy harvesting). These polymers are specifically used to immobilize redox mediators on electrode surfaces, allowing for self-exchange-based conduction of electrons from enzymes far from the electrode to the electrode surface. However, the synthesis of redox polymers is challenging and results in large batch-to-batch variability. Herein, we report a rapid entrapment of mediators for NAD-dependent bioelectrocatalysis within reverse ionically condensed polyelectrolytes. A high ionic strength aqueous solution of oppositely charged polyelectrolytes, composed of cationic polyguanidinium (PG) chloride and anionic sodium hexametaphosphate (P6), undergoes phase inversion into a solid microporous polyelectrolyte complex (PEC) when introduced into a low ionic strength aqueous solution. The ionic strength-triggered phase inversion of PGP6 solutions was investigated as a means to entrap mediators on the surface of electrodes for mediated bioelectrocatalysis. Compared to the traditional cross-linked immobilizations using redox polymers, this phase inversion takes place within seconds and requires up to 60 min for complete stabilization. In this work, redox mediator phenazine ethosulfate (PES) was entrapped within PGP6 on electrode surfaces for nicotinamide adenine dinucleotide (NAD)-dependent bioelectrocatalysis. In the bulk solution, NAD-dependent dehydrogenase enzymes catalyze the oxidation of the substrate while reducing NAD to reduced nicotinamide adenine dinucleotide (NADH). The resulting NADH is reoxidized to NAD by the entrapped PES that gets reduced on the electrode, completing the NAD-regeneration-based bioelectrocatalysis. To show the use of these new materials in an application, biofuel cells were evaluated using four different anodic enzyme systems (alcohol dehydrogenase, lactate hydrogenase, glycerol dehydrogenase, and glucose dehydrogenase).
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http://dx.doi.org/10.1021/acsami.0c22302DOI Listing
March 2021

Advances in Electrochemical Modification Strategies of 5-Hydroxymethylfurfural.

ChemSusChem 2021 Apr 24;14(7):1674-1686. Epub 2021 Feb 24.

Department of Chemistry, University of Utah, 315 S 1400 E, RM 2020, Salt Lake City, UT, 84112, USA.

The development of electrochemical catalytic conversion of 5-hydroxymethylfurfural (HMF) has recently gained attention as a potentially scalable approach for both oxidation and reduction processes yielding value-added products. While the possibility of electrocatalytic HMF transformations has been demonstrated, this growing research area is in its initial stages. Additionally, its practical applications remain limited due to low catalytic activity and product selectivity. Understanding the catalytic processes and design of electrocatalysts are important in achieving a selective and complete conversion into the desired highly valuable products. In this Minireview, an overview of the most recent status, advances, and challenges of oxidation and reduction processes of HMF was provided. Discussion and summary of voltammetric studies and important reaction factors (e. g., catalyst type, electrode material) were included. Finally, biocatalysts (e. g., enzymes, whole cells) were introduced for HMF modification, and future opportunities to combine biocatalysts with electrochemical methods for the production of high-value chemicals from HMF were discussed.
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http://dx.doi.org/10.1002/cssc.202100139DOI Listing
April 2021

Ethanol Biofuel Cells: Hybrid Catalytic Cascades as a Tool for Biosensor Devices.

Biosensors (Basel) 2021 Feb 4;11(2). Epub 2021 Feb 4.

Department of Chemistry, Faculty of Philosophy Sciences and Letters at Ribeirão Preto, University of São Paulo, Ribeirão Preto, Sao Paulo 14040-901, Brazil.

Biofuel cells use chemical reactions and biological catalysts (enzymes or microorganisms) to produce electrical energy, providing clean and renewable energy. Enzymatic biofuel cells (EBFCs) have promising characteristics and potential applications as an alternative energy source for low-power electronic devices. Over the last decade, researchers have focused on enhancing the electrocatalytic activity of biosystems and on increasing energy generation and electronic conductivity. Self-powered biosensors can use EBFCs while eliminating the need for an external power source. This review details improvements in EBFC and catalyst arrangements that will help to achieve complete substrate oxidation and to increase the number of collected electrons. It also describes how analytical techniques can be employed to follow the intermediates between the enzymes within the enzymatic cascade. We aim to demonstrate how a high-performance self-powered sensor design based on EBFCs developed for ethanol detection can be adapted and implemented in power devices for biosensing applications.
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http://dx.doi.org/10.3390/bios11020041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913944PMC
February 2021

Cascaded Biocatalysis and Bioelectrocatalysis: Overview and Recent Advances.

Annu Rev Phys Chem 2021 04 27;72:467-488. Epub 2021 Jan 27.

Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA; email:

Enzyme cascades are plentiful in nature, but they also have potential in artificial applications due to the possibility of using the target substrate in biofuel cells, electrosynthesis, and biosensors. Cascade reactions from enzymes or hybrid bioorganic catalyst systems exhibit extended substrate range, reaction depth, and increased overall performance. This review addresses the strategies of cascade biocatalysis and bioelectrocatalysis for () CO fixation, () high value-added product formation, () sustainable energy sources via deep oxidation, and () cascaded electrochemical enzymatic biosensors. These recent updates in the field provide fundamental concepts, designs of artificial electrocatalytic oxidation-reduction pathways (using a flexible setup involving organic catalysts and engineered enzymes), and advances in hybrid cascaded sensors for sensitive analyte detection.
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http://dx.doi.org/10.1146/annurev-physchem-090519-050109DOI Listing
April 2021

Electroreductive Olefin-Ketone Coupling.

J Am Chem Soc 2020 12 1;142(50):20979-20986. Epub 2020 Dec 1.

Department of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla 92037, California, United States.

A user-friendly approach is presented to sidestep the venerable Grignard addition to unactivated ketones to access tertiary alcohols by reversing the polarity of the disconnection. In this work a ketone instead acts as a nucleophile when adding to simple unactivated olefins to accomplish the same overall transformation. The scope of this coupling is broad as enabled using an electrochemical approach, and the reaction is scalable, chemoselective, and requires no precaution to exclude air or water. Multiple applications demonstrate the simplifying nature of the reaction on multistep synthesis, and mechanistic studies point to an intuitive mechanism reminiscent of other chemical reductants such as SmI (which cannot accomplish the same reaction).
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http://dx.doi.org/10.1021/jacs.0c11214DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8353665PMC
December 2020

Draft Genome Sequence of sp. Strain EAGSL, a Biotechnologically Relevant Halophilic Microorganism.

Microbiol Resour Announc 2020 Oct 22;9(43). Epub 2020 Oct 22.

Department of Chemistry, University of Utah, Salt Lake City, Utah, USA

The halophilic bacterium sp. strain EAGSL was isolated from the Great Salt Lake (Utah) for use in microbial electrochemical technologies experiencing fluctuating salt concentrations. Genome sequencing was performed with Ion Torrent technology, and the assembled genome reported here is 3,234,770 bp with a GC content of 49.41%.
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http://dx.doi.org/10.1128/MRA.01020-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7585845PMC
October 2020

Fundamentals, Applications, and Future Directions of Bioelectrocatalysis.

Chem Rev 2020 12 14;120(23):12903-12993. Epub 2020 Oct 14.

Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States.

Bioelectrocatalysis is an interdisciplinary research field combining biocatalysis 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.
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http://dx.doi.org/10.1021/acs.chemrev.0c00472DOI Listing
December 2020

Chloroplast biosolar cell and self-powered herbicide monitoring.

Chem Commun (Camb) 2020 Nov 5;56(86):13161-13164. Epub 2020 Oct 5.

Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, UT 84112, USA.

Utilizing chloroplasts in biosolar cells offers a sustainable approach for sunlight harvesting. However, the limited electrochemical communication between these biological entities and an electrode surface has led to complex device setups, hindering their application in the field. Herein, a cross-linker enables a simple photoanode architecture with enhanced photoexcited electron transfer between chloroplasts and abiotic electrodes. The improved "wiring" of the photosynthetic electron transfer chain resulted in a five-fold increase in the biophotocurrent. The biophotoanode is applied in a Pt-free, portable biosolar cell allowing the in situ self-powered monitoring of diuron within limits set by the Environmental Protection Agency.
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http://dx.doi.org/10.1039/d0cc03787gDOI Listing
November 2020

Using nature's blueprint to expand catalysis with Earth-abundant metals.

Science 2020 08;369(6505)

Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Numerous redox transformations that are essential to life are catalyzed by metalloenzymes that feature Earth-abundant metals. In contrast, platinum-group metals have been the cornerstone of many industrial catalytic reactions for decades, providing high activity, thermal stability, and tolerance to chemical poisons. We assert that nature's blueprint provides the fundamental principles for vastly expanding the use of abundant metals in catalysis. We highlight the key physical properties of abundant metals that distinguish them from precious metals, and we look to nature to understand how the inherent attributes of abundant metals can be embraced to produce highly efficient catalysts for reactions crucial to the sustainable production and transformation of fuels and chemicals.
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http://dx.doi.org/10.1126/science.abc3183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875315PMC
August 2020

Vibrational Spectroscopic Monitoring of the Gelation Transition in Nafion Ionomer Dispersions.

Appl Spectrosc 2021 Apr 12;75(4):376-384. Epub 2020 Oct 12.

Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA.

Infrared and Raman spectroscopy techniques were applied to investigate the drying and aggregation behavior of Nafion ionomer particles dispersed in aqueous solution. Gravimetric measurements aided the identification of gel-phase development within a series of time-resolved spectra that tracked transformations of a dispersion sample during solvent evaporation. A spectral band characteristic of ionomer sidechain end group vibration provided a quantitative probe of the dispersion-to-gel change. For sets of attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra, adherence to Beer's law was attributed to the relatively constant refractive index in the frequency region of hydrated - group vibrations as fluorocarbon-rich ionomer regions aggregate in forming the structural framework of membranes and thin films. Although vibrational bands associated with ionomer backbone CF stretching vibrations were affected by distortion characteristic of wavelength-dependent refractive index change within a sample, the onset of band distortion signaled gel formation and coincided with ionomer mass % values just below the critical gelation point for Nafion aqueous dispersions. Similar temporal behavior was observed in confocal Raman microscopy experiments that monitored the formation of a thin ionomer film from an individual dispersion droplet. For the ATR FT-IR spectroscopy and confocal Raman microscopy techniques, intensity in the water H-O-H bending vibrational band dropped sharply at the ionomer critical gelation point and displayed a time dependence consistent with changes in water content derived from gravimetric measurements. The reported studies lay groundwork for examining the impact of dispersing solvents and above-ambient temperatures on fluorinated ionomer transformations that influence structural properties of dispersion-cast membranes and thin films.
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http://dx.doi.org/10.1177/0003702820949129DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8027933PMC
April 2021

Cytochrome c oxidase oxygen reduction reaction induced by cytochrome c on nickel-coordination surfaces based on graphene oxide in suspension.

Biochim Biophys Acta Bioenerg 2020 11 14;1861(11):148262. Epub 2020 Jul 14.

Department of Chemistry and Environmental Science, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY 11225, USA; The Graduate Center of CUNY, New York, NY 10016, USA. Electronic address:

Background: The electrochemical and spectroscopic investigation of bacterial electron-transfer proteins stabilized on solid state electrodes has provided an effective approach for functional respiratory enzyme studies.

Methods: We assess the biocompatibility of carboxylated graphene oxide (CGO) functionalized with Nickel nitrilotriacetic groups (CGO-NiNTA) ccordinating His-tagged cytochrome c oxidase (CcO) from Rhodobacter sphaeroides.

Results: Kinetic studies employing UV-visible absorption spectroscopy confirmed that the immobilized CcO oxidized horse-heart cytochrome c (Cyt c) albeit at a slower rate than isolated CcO. The oxygen reduction reaction as catalyzed by immobilized CcO could be clearly distinguished from that arising from CGO-NiNTA in the presence of Cyt c and dithiothreitol (DTT) as a sacrificial reducing agent. Our findings indicate that while the protein content is about 3.7‰ by mass with respect to the support, the contribution to the oxygen consumption activity averaged at 56.3%.

Conclusions: The CGO-based support stabilizes the free enzyme which, while capable of Cyt c oxidation, is unable to carry out oxygen consumption in solution on its own under our conditions. The turnover rate for the immobilized CcO was as high as 240 O molecules per second per CcO unit.

General Significance: In vitro investigations of electron flow on isolated components of bacterial electron-transfer enzymes immobilized on the surface of CGO in suspension are expected to shed new light on microbial bioenergetic functions, that could ultimately contribute toward the improvement of performance in living organisms.
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http://dx.doi.org/10.1016/j.bbabio.2020.148262DOI Listing
November 2020

Advancing the fundamental understanding and practical applications of photo-bioelectrocatalysis.

Chem Commun (Camb) 2020 Aug 24;56(61):8553-8568. Epub 2020 Jun 24.

Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, UT 84112, USA.

Photo-bioelectrocatalysis combines the natural and highly sophisticated process of photosynthesis in biological entities with an abiotic electrode surface, to perform semi-artificial photosynthesis. However, challenges must be overcome, from the establishment and understanding of the photoexcited electron harvesting process at the electrode to the electrochemical characterization of these biotic/abiotic systems, and their subsequent tuning for enhancing energy generation (chemical and/or electrical). This Feature Article discusses the various approaches utilized to tackle these challenges, particularly focusing on powerful multi-disciplinary approaches for understanding and improving photo-bioelectrocatalysis. Among them is the combination of experimental evidence and quantum mechanical calculations, the use of bioinformatics to understand photo-bioelectrocatalysis at a metabolic level, or bioengineering to improve and facilitate photo-bioelectrocatalysis. Key aspects for the future development of photo-bioelectrocatalysis are presented alongside future research needs and promising applications of semi-artificial photosynthesis.
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http://dx.doi.org/10.1039/d0cc02672gDOI Listing
August 2020

Elucidating the Mechanism behind the Bionanomanufacturing of Gold Nanoparticles Using .

ACS Appl Bio Mater 2020 Jun 4;3(6):3859-3867. Epub 2020 Jun 4.

Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah84112, United States.

Over the last two decades, gold nanoparticles (GNPs) have opened up numerous research and industrial opportunities in biomedical, optical, and electronic fields due to their size- and morphology-dependent properties [Grassian, V. H. 2008, 112(47), 18303-18313 and Nehl, C. L.; Hafner, J. H. 2008, 18(21), 2415-2419]. Therefore, green and efficient synthesis strategies providing precise control over size and morphology are desired. Since biological catalysts are known for the selectivity, efficiency, and environmentally friendly production of gold nanoparticles (referred to as bionanomanufacturing), they have been considered for GNP synthesis. However, the mechanism of how most of these biological entities produce GNPs has not been elucidated to date, limiting the industrial implementation of complex biological systems for nanoparticle synthesis. In this study, we investigated the mechanism of extracellular GNP production by (). It is shown that releases vegetative catalase (Cat A) into the supernatant. Cat A from the supernatant and commercial catalase were employed to establish the mechanism of GNP formation. The bionanomanufactured GNPs were characterized using ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). Based on our results, we theorize that the mechanism of extracellular GNP production by Cat A involves (1) formation of gold-thiol bonds followed by (2) stabilization of GNPs with the denatured bacterial protein that serves as a capping agent. This research offers early insights into the gold-reducing mechanism occurring in the cell-free extract of , which can potentially lead to the design of protocols for the controlled production of GNPs with isolated enzymes at the industrial scale.
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http://dx.doi.org/10.1021/acsabm.0c00420DOI Listing
June 2020

Energy storage emerging: A perspective from the Joint Center for Energy Storage Research.

Proc Natl Acad Sci U S A 2020 Jun;117(23):12550-12557

Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, IL 60439.

Energy storage is an integral part of modern society. A contemporary example is the lithium (Li)-ion battery, which enabled the launch of the personal electronics revolution in 1991 and the first commercial electric vehicles in 2010. Most recently, Li-ion batteries have expanded into the electricity grid to firm variable renewable generation, increasing the efficiency and effectiveness of transmission and distribution. Important applications continue to emerge including decarbonization of heavy-duty vehicles, rail, maritime shipping, and aviation and the growth of renewable electricity and storage on the grid. This perspective compares energy storage needs and priorities in 2010 with those now and those emerging over the next few decades. The diversity of demands for energy storage requires a diversity of purpose-built batteries designed to meet disparate applications. Advances in the frontier of battery research to achieve transformative performance spanning energy and power density, capacity, charge/discharge times, cost, lifetime, and safety are highlighted, along with strategic research refinements made by the Joint Center for Energy Storage Research (JCESR) and the broader community to accommodate the changing storage needs and priorities. Innovative experimental tools with higher spatial and temporal resolution, in situ and operando characterization, first-principles simulation, high throughput computation, machine learning, and artificial intelligence work collectively to reveal the origins of the electrochemical phenomena that enable new means of energy storage. This knowledge allows a constructionist approach to materials, chemistries, and architectures, where each atom or molecule plays a prescribed role in realizing batteries with unique performance profiles suitable for emergent demands.
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http://dx.doi.org/10.1073/pnas.1821672117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293617PMC
June 2020

Electroenzymatic Nitrogen Fixation Using a MoFe Protein System Immobilized in an Organic Redox Polymer.

Angew Chem Int Ed Engl 2020 09 22;59(38):16511-16516. Epub 2020 Jul 22.

Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah, 84112, USA.

We report an organic redox-polymer-based electroenzymatic nitrogen fixation system using a metal-free redox polymer, namely neutral-red-modified poly(glycidyl methacrylate-co-methylmethacrylate-co-poly(ethyleneglycol)methacrylate) with a low redox potential of -0.58 V vs. SCE. The stable and efficient electric wiring of nitrogenase within the redox polymer matrix enables mediated bioelectrocatalysis of N , NO and N to NH catalyzed by the MoFe protein via the polymer-bound redox moieties distributed in the polymer matrix in the absence of the Fe protein. Bulk bioelectrosynthetic experiments produced 209±30 nmol NH  nmol MoFe  h from N reduction. N labeling experiments and NMR analysis were performed to confirm biosynthetic N reduction to NH .
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http://dx.doi.org/10.1002/anie.202007198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7540466PMC
September 2020
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