Robert L Arechederra

Saint Louis University, Saint Louis, MI, United States

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Publications (20)70.44 Total impact

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    ABSTRACT: Obesity is quickly becoming an increasing problem in the developed world. One of the major fundamental causes of obesity and diabetes is mitochondria dysfunction due to faulty metabolic pathways which alter the metabolic substrate flux resulting in the development of these diseases. This paper examines the role of mitochondrial carbonic anhydrase (CA) isozymes in the metabolism of pyruvate, acetate, and succinate when specific isozyme inhibitors are present. Using a sensitive electrochemical approach of wired mitochondria to analytically measure metabolic energy conversion, we determine the resulting metabolic difference after addition of an inhibitory compound. We found that certain sulfonamide analogues displayed broad spectrum inhibition of metabolism, where others only had significant effect on some metabolic pathways. Pyruvate metabolism always displayed the most dramatically affected metabolism by the sulfonamides followed by fatty acid metabolism, and then finally succinate metabolism. This allows for the possibility of using designed sulfonamide analogues to target specific mitochondrial CA isozymes in order to subtly shift metabolism and glucogenesis flux to treat obesity and diabetes.
    Bioorganic & medicinal chemistry 07/2012; · 2.82 Impact Factor
  • Robert L Arechederra, Abdul Waheed, William S Sly, Shelley D Minteer
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    ABSTRACT: In the continual search of new therapeutics, many possible drug candidates are excluded, because they are found to negatively affect mitochondrial function. We have developed an approach for directly, electrochemically assaying mitochondrial metabolic activity as a function of metabolic substrate to determine drug toxicity. By wiring mouse mitochondria to a carbon electrode surface, electrons can be intercepted before they reach Complex IV, the terminal step of electron transport chain. The electrons are rerouted, to a separate electrode of the electrochemical cell, the cathode. This allows for the direct measurement of electrical current and potential of the mitochondria during their oxidation of substrates such as pyruvate and fatty acids when there are different concentrations of drug present. This analytical technique has been shown to reliably assay several classical mitochondrial toxins and exhibits potential for the further development of a drug candidate screening technique, as well as other applications where the quantitative study of mitochondrial dysfunction is important.
    The Analyst 07/2011; 136(18):3747-52. · 4.23 Impact Factor
  • Robert L Arechederra, Shelley D Minteer
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    ABSTRACT: One of the problems associated with miniaturization and portability of sensors is the power supply. Power supplies, such as batteries, are difficult to miniaturize and require a sensor design that allows for easy replacement or recharging. This review describes the field of self-powered sensing, where the sensor itself provides the power for the sensing device. Most self-powered-sensing strategies employ either nuclear energy conversion or electrochemical energy conversion. Nuclear energy conversion is employed for radioisotope or nuclear reactor sensing. Electrochemical energy conversion is employed for chemical and biological sensing. This review details the common strategies for self-powered nuclear, chemical, and biological sensing and discusses the future of the technology.
    Analytical and Bioanalytical Chemistry 02/2011; 400(6):1605-11. · 3.66 Impact Factor
  • Paul K. Addo, Robert L. Arechederra, Shelley D. Minteer
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    ABSTRACT: This research focused on the transition of biofuel cell technology to rechargeable biobatteries. The bioanode compartment of the biobattery consisted of NAD-dependent alcohol dehydrogenase (ADH) immobilized into a carbon composite paste with butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid serving as the electrolyte. Ferrocene was added to shuttle electrons to/from the electrode surface/current collector. The bioanode catalyzed the oxidation of ethanol to acetaldehyde in discharge mode. This bioanode was coupled to a cathode that consisted of Prussian Blue in a carbon composite paste with Nafion 212 acting as the separator between the two compartments. The biobattery can be fabricated in a charged mode with ethanol and have an open circuit potential of 0.8V in the original state prior to charging or in the discharged mode with acetaldehyde and have an open circuit potential of 0.05V. After charging it has an open circuit potential of 1.2V and a maximum power density of 13.0μWcm−3 and a maximum current density of 35.0μAcm−3, respectively. The stability and efficiency of the biobattery were studied by cycling continuously at a discharging current of 0.4mA and the results obtained showed reasonable stability over 50 cycles. This is a new type of secondary battery inspired by the metabolic processes of the living cell, which is an effective energy conversion system.
    Journal of Power Sources 01/2011; 196(7):3448-3451. · 5.26 Impact Factor
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    ABSTRACT: Electrocatalytic prodn. of methanol from CO2 has recently been studied. This paper focuses on understanding the role of carbonic anhydrase to efficiently facilitate uptake of CO2, which can be the rate detg. step. The three oxidoreductase enzymes responsible for CO2 redn. to methanol are formate, aldehyde, and alc. dehydrogenase. This enzyme cascade was coupled to a poly(neutral red) modified electrode to regenerate NADH. We have found that the dehydrogenases alone can achieve redn. of CO2, but the process is accelerated by the addn. of carbonic anhydrase. As researchers focus on electrofuels, carbonic anhydrase will likely improve performance. [on SciFinder(R)]
    Electrochemical and Solid-State Letters 01/2011; 14(4):E9-E13. · 2.01 Impact Factor
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    ABSTRACT: Precious metal alloys have been the predominant electrocatalyst used for oxygen reduction in fuel cells since the 1960s. Although performance of these catalysts is high, they do have drawbacks. The two main problems with precious metal alloys are catalyst passivation and cost. This is why new novel catalysts are being developed and employed for oxygen reduction. This paper details the low temperature solvothermal synthesis and characterization of carbon nanotubes that have been doped with both iron and cobalt centered phthalocyanine. The synthesis is a novel low-temperature, supercritical solvent synthesis that reduces halocarbons to form a metal chloride byproduct and carbon nanotubes. Perchlorinated phthalocyanine was added to the nanotube synthesis to incorporate the phthalocyanine structure into the graphene sheets of the nanotubes to produce doped nanotubes that have the catalytic oxygen reduction capabilities of the metallo-phthalocyanine and the advantageous material qualities of carbon nanotubes. The cobalt phthalocyanine doped carbon nanotubes showed a half wave oxygen reduction potential of -0.050 ± 0.005 V vs Hg\HgO, in comparison to platinum's half wave oxygen reduction potential of -0.197 ± 0.002 V vs Hg\HgO.
    ACS Applied Materials & Interfaces 11/2010; 2(11):3295-302. · 5.90 Impact Factor
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    ABSTRACT: Although mitochondria have long been considered the powerhouse of the living cell, it is only recently that we have been able to employ these organelles for electrocatalysis in electrochemical energy conversion devices. The concept of using biological entities for energy conversion, commonly referred to as a biofuel cell, has been researched for nearly a century, but until recently the biological entities were limited to microbes or isolated enzymes. However, from the perspectives of efficient energy conversion and high volumetric catalytic activity, mitochondria may be a possible compromise between the efficiency of microbial biofuel cells and the high volumetric catalytic activity of enzymatic biofuel cells. This perspective focuses on comparing mitochondrial biofuel cells to other types of biofuel cells, as well as studying the fuel diversity that can be employed with mitochondrial biofuel cells. Pyruvate and fatty acids have previously been studied as fuels, but this perspective shows evidence that amino acids can be employed as fuels as well.
    Physical Chemistry Chemical Physics 11/2010; 13(1):86-92. · 4.20 Impact Factor
  • Paul K. Addo, Robert L. Arechederra, Shelley D. Minteer
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    ABSTRACT: Previous work by the group has entailed encapsulating enzymes in polymeric micelles at bioelectrode surfaces by utilizing hydrophobically modified Nafion membranes, which are modified in order to eliminate the harsh acidity of Nafion while tailoring the size of the polymer micelles to optimize for the encapsulation of an individual enzyme. This polymer encapsulation has been shown to provide high catalytic activity and enzyme stability. In this study, we employed this encapsulation technique in developing a methanol/air biofuel cell through the combined immobilization of NAD+-dependent alcohol dehydrogenase (ADH), aldehyde dehydrogenase (AldDH) and formate dehydrogenase (FDH) within a tetrabutylammonium bromide (TBAB) modified Nafion to oxidize methanol to carbon dioxide with poly(methylene green) acting as the NADH electrocatalyst electropolymerized on the surface of the electrode. The methanol biofuel/air cell resulted in a maximum power density of 261±7.6 μW/cm2 and current density of 845±35.5 μA/cm2. This system was characterized for the effects of degree of oxidation, temperature, pH, and concentration of fuel and NAD.
    Electroanalysis 03/2010; 22(7‐8):807 - 812. · 2.82 Impact Factor
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    ABSTRACT: Enzymatic biofuel cells have employed a variety of fuels, including: glucose, fructose, methanol, ethanol, glycerol, lactate, pyruvate and ethylene glycol. This review describes the wealth of fuel diversity in enzymatic biofuel cells, along with the use of multi-enzyme cascades for deep or complete oxidation of biofuels at the anode of enzymatic biofuel cells. Deep or complete oxidation is a relatively new research area for enzymatic biofuel cells, but it is necessary to increase energy density and minimize product inhibition effects.
    Electroanalysis 02/2010; 22(7‐8):757 - 764. · 2.82 Impact Factor
  • Robert L. Arechederra, Shelley D. Minteer
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    ABSTRACT: Glycerol has drawn increasing attention as a possible fuel, because it has many desirable qualities and is abundant due to the fact that it is a byproduct of biodiesel production. Previous research has shown that non-natural enzyme cascades can be used to create a bioanode that can stepwise oxidize glycerol to carbon dioxide. Two of these enzymes are pyrroloquinoline quinone (PQQ) dependant alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AldDH) derived from Gluconobacter. The third enzyme, which is responsible for carbon bond cleavage, is oxalate oxidase (OxOx) derived from barley. Previous research has shown that all three enzymes have demonstrated the ability to undergo direct electron transfer to a carbon electrode which allows for a simple and efficient bioanode that completely oxidizes glycerol. In this study, each enzyme was individually immobilized within modified Nafion® on a glassy carbon rotating disc electrode (GC-RDE) and voltammetric analysis was performed employing different rotation rates in a solution containing each enzyme's respective substrate. This substrate was glycerol for alcohol dehydrogenase, glyceraldehyde for aldehyde dehydrogenase, and mesoxalic acid for oxalate oxidase. From the voltammograms, Levich plots were produced and the solution diffusion coefficient (Dsoln), the membrane diffusion coefficient (Dfilm), kCAT, KM, and VMAX were determined.
    Electrochimica Acta 01/2010; 55(26):7679-7682. · 4.09 Impact Factor
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    ABSTRACT: Enzymatic biofuel cells, which replace expensive metal catalysts with enzymes, are still in an early stage of development. This article details the analytical techniques that are often employed for evaluating and characterizing enzymatic biofuel cells and their corresponding bioanodes and biocathodes. (To listen to a podcast about this feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.).
    Analytical Chemistry 11/2009; 81(23):9538-45. · 5.82 Impact Factor
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    ABSTRACT: Mitochondria are unique organelles in which they contain multiple metabolic pathways and contain all the enzymes necessary to completely oxidize pyruvate and fatty acids. They are generally considered the "powerhouse" of the living cell. We have investigated strategies for mediated and direct bioelectrocatalysis of mitochondria at carbon electrodes. These mitochondria modified electrodes have been used for oxidation of pyruvate and fatty acids in organelle-based biofuel cells and for self-powered explosive sensing due to the unique ability to actuate power in the presence and absence of nitroaromatic explosives.
    41st American Chemical Society Central Regional Meeting; 05/2009
  • Becky L Treu, Robert Arechederra, Shelley D Minteer
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    ABSTRACT: In bioelectrocatalysis, nanomaterials are typically used as a conductive bridge for the gap between the site of oxidation/reduction (i.e., enzymatic biocatalyst) and the current collector (electrode). In this paper, carbon nanomaterial supports have been employed in conjunction with heme-c containing pyrroloquinoline quinone-dependent alcohol dehydrogenase (PQQ-ADH) and aldehyde dehydrogenase (PQQ-AldDH) oxidoreductase enzymes as oxidation catalysts to produce stable high surface area catalyst supports for the bioelectrocatalysis of ethanol in biofuel cells. The structure of PQQ-ADH and PQQ-AldDH allow for direct electron transfer (DET) between the enzymes and carbon nanomaterial support without the use of additional charge carrying chemical mediators. In this paper, the employment of nanomaterials are used to produce stable, high surface area catalyst supports which aid in enzyme adsorption and direct electron transfer. Fundamental DET studies were performed on both PQQ-ADH and PQQ-AldDH in order to understand the processes occurring at the electrode surface. Data shows a direct correlation between concentration of substrate and peak potential and peak current. Incorporating nanotubes into this technology has allowed an increase in the current density of ethanol/air biofuel cells by up to 14.5 fold and increased the power density by up to 18.0 fold.
    Journal of Nanoscience and Nanotechnology 05/2009; 9(4):2374-80. · 1.15 Impact Factor
  • Robert L. Arechederra, Kevin Boehm, Shelley D. Minteer
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    ABSTRACT: Mitochondria modified electrodes have been developed and characterized that utilize whole mitochondria isolated from tubers and immobilized within a quaternary ammonium modified Nafion membrane on a carbon electrode that can oxidize pyruvate and fatty acids. Detailed characterization of the performance of these mitochondria modified electrodes has been accomplished by coupling the mitochondria-based bioanode with a commercial air breathing cathode in a complete pyruvate/air biofuel cell. The studies included the effect of fuel (pyruvate) concentration, mitochondria lysing, temperature and pH on the performance of the mitochondria catalyzed, pyruvate/air biofuel cell. Effect of oxygen and cytochrome c oxidase inhibitors on biofuel cell performance has allowed us to further understand the mechanism of electron transfer with the carbon electrode.
    Electrochimica Acta 01/2009; · 4.09 Impact Factor
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    Marguerite N Germain, Robert L Arechederra, Shelley D Minteer
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    ABSTRACT: Oligomycin-inhibited mitochondria-modified electrodes were used to electrochemically sense the presence of nitroaromatics owing to the selective ability of nitroaromatics to decouple the inhibition of pyruvate metabolism by the mitochondria. These oligomycin inhibited mitochondria-modified electrodes were employed as the bioanode in a pyruvate/air biofuel cell. This sensing mechanism could be used as a traditional electrochemical sensor or as a self-powered sensor.
    Journal of the American Chemical Society 11/2008; 130(46):15272-3. · 10.68 Impact Factor
  • Robert Arechederra, Shelley D. Minteer
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    ABSTRACT: This paper details the development of a mitochondria-based biofuel cell. We show that mitochondria can be immobilized at a carbon electrode surface and remain intact and viable. The electrode-bound mitochondria drive complete oxidation of pyruvate as shown by Carbon-13 NMR and serve as the anode of the biofuel cell where they convert the chemical energy in a biofuel (such as pyruvate) into electrical energy. These are the first organelle-based fuel cells. Researchers have previously used isolated enzymes and complete microbes for fuel cells, but this is the first evidence that organelles can support fuel cell-based energy conversion. These biofuel cells provide power densities of 0.203 ± 0.014 mW/cm2, which is in between the latest immobilized enzyme-based biofuel cells and microbial biofuel cells, while providing the efficiency of microbial biofuel cells.
    Electrochimica Acta 10/2008; 53(23):6698-6703. · 4.09 Impact Factor
  • R. L. Arechederra, S. D. Minteer
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    ABSTRACT: Glycerol has drawn increasing attention as a prospective fuel because it has many desirable qualities and is abundant due to the fact that it is a by-product of biodiesel production. Qualities such as nontoxicity, extremely low vapour pressure, low flammability and high energy density make glycerol very appealing as an energy source. Previous research has shown that partial oxidation of glycerol can occur at enzymatic bioanodes of biofuel cells utilising PQQ-dependent alcohol dehydrogenase (PQQ-ADH) and PQQ-dependent aldehyde dehydrogenase (PQQ-AldDH). In this paper, we describe the use of glycerol for a fuel in an enzymatic biofuel cell that utilizes a three-enzyme cascade on the anode that can accomplish the complete oxidation of glycerol. The bioanode that was developed contained PQQ-ADH, PQQ-AldDH and oxalate oxidase immobilised within a tetrabutylammonium-modified Nafion membrane. Our previous research has shown that glycerol is an effective fuel with the PQQ-ADH and PQQ-AldDH but still was unable to be fully oxidised. With the addition of oxalate oxidase, these glycerol/air biofuel cells have yielded power densities of up to 1.32 mW cm–2, and have the ability to operate at high fuel concentrations. The oxidation products were confirmed with 13C NMR and comprised mainly 13C-labelled carbonate and glycerate.
    Fuel Cells 07/2008; 9(1):63 - 69. · 1.55 Impact Factor
  • Robert L. Arechederra, Becky L. Treu, Shelley D. Minteer
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    ABSTRACT: Glycerol is an attractive fuel for a fuel cell, because it is non-toxic, non-volatile, non-flammable, has high energy density, and is abundant due to the fact that it is a byproduct of biodiesel production. However, it has not been an effective fuel for low temperature, precious metal catalyzed fuel cells. In this paper, we describe the use of glycerol as a fuel in an enzymatic biofuel cell. An alcohol dehydrogenase and aldehyde dehydrogenase-based bioanode has been developed that oxidizes glycerol, a safe high energy density fuel. Glycerol/O2 biofuel cells employing these bioanodes have yielded power densities of up to 1.21mWcm−2, and have the ability to operate at 98.9% fuel concentrations. Previous biofuel cells could not operate effectively at high fuel concentrations due to the nature of the solid fuel such as sugar or the solvent characteristics of fuels such as lower aliphatic alcohols. The glycerol/O2 biofuel cell provides improved power densities compared to ethanol biofuel cells due to ability to more completely oxidize the fuel.
    Journal of Power Sources 01/2007; 173(1):156-161. · 5.26 Impact Factor
  • Robert L. Arechederra, Shelley Minteer