g-CN/Chlorocobaloxime Nanocomposites as Multifunctional Electrocatalysts for Water Splitting and Energy Storage.

Due to environmental contamination and the depletion of energy supplies, it is very important to develop low-cost, high-performance, multifunctional electrocatalysts for energy conversion and storage systems. Herein, we report the development of cost-effective modified electrodes containing g-CN/chlorocobaloxime composites (C1-C4) and their electrocatalytic behavior toward the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), followed by their energy-storage applications. A series of chlorocobaloximes {ClCo(dpgH)B} with diphenylglyoxime (dpgH) and neutral bases (B) containing a carboxylic acid moiety (isonicotinic acid, pyridine-3,5-dicarboxylic acid, indole-2-carboxylic acid, and p-aminobenzoic acid) have been synthesized and characterized by spectroscopic techniques.

Copper(II)-Bis-Cyclen Intercalated Graphene Oxide as an Efficient Two-Dimensional Nanocomposite Material for Copper-Catalyzed Azide-Alkyne Cycloaddition Reaction.

We report stable and heterogeneous graphene oxide (GO)-intercalated copper as an efficient catalyst for the organic transformations in green solvents. The GO-intercalated copper(II) complex of bis(1,4,7,10-tetraazacyclododecane) [Cu(II)-bis-cyclen] was prepared by a facile synthetic approach with a high dilution technique. The as-prepared GO-Cu(II)-bis-cyclen nanocomposite was used as a click catalyst for the 1,3 dipolar Huisgen cycloaddition reaction of terminal alkyne and azide substrates.

Microsystems for biofilm characterization and sensing - A review.

Biofilms are the primary cause of clinical bacterial infections and are impervious to typical amounts of antibiotics, necessitating very high doses for elimination. Therefore, it is imperative to have suitable methods for characterization to develop novel methods of treatment that can complement or replace existing approaches using significantly lower doses of antibiotics. This review presents some of the current developments in microsystems for characterization and sensing of bacterial biofilms.

Flexible Platform for In Situ Impedimetric Detection and Bioelectric Effect Treatment of Escherichia Coli Biofilms.

Goal: This paper reports a platform for real-time monitoring and treatment of biofilm formation on three-dimensional biomedical device surfaces.

Methods: We utilize a flexible platform consisting of gold interdigitated electrodes patterned on a polyimide substrate. The device was integrated onto the interior of a urinary catheter and characterization was performed in a custom-developed flow system.

An Integrated Microsystem for Real-Time Detection and Threshold-Activated Treatment of Bacterial Biofilms.

Bacterial biofilms are the primary cause of infections in medical implants and catheters. Delayed detection of biofilm infections contributes to the widespread use of high doses of antibiotics, leading to the emergence of antibiotic-resistant bacterial strains. Accordingly, there is an urgent need for systems that can rapidly detect and treat biofilm infections in situ.

Autoinducer-2 analogs and electric fields - an antibiotic-free bacterial biofilm combination treatment.

Bacterial biofilms are a common cause of chronic medical implant infections. Treatment and eradication of biofilms by conventional antibiotic therapy has major drawbacks including toxicity and side effects associated with high-dosage antibiotics. Additionally, administration of high doses of antibiotics may facilitate the emergence of antibiotic resistant bacteria.

Effect of electrical energy on the efficacy of biofilm treatment using the bioelectric effect.

Background/objectives: The use of electric fields in combination with small doses of antibiotics for enhanced treatment of biofilms is termed the 'bioelectric effect' (BE). Different mechanisms of action for the AC and DC fields have been reported in the literature over the last two decades. In this work, we conduct the first study on the correlation between the electrical energy and the treatment efficacy of the bioelectric effect on K-12 W3110 biofilms.

Spectroscopic and redox studies of valence-delocalized [Fe2S2](+) centers in thioredoxin-like ferredoxins.

Reduced forms of the C56S and C60S variants of the thioredoxin-like Clostridium pasteurianum [Fe2S2] ferredoxin (CpFd) provide the only known examples of valence-delocalized [Fe2S2](+) clusters, which constitute a fundamental building block of all higher nuclearity Fe-S clusters. In this work, we have revisited earlier work on the CpFd variants and carried out redox and spectroscopic studies on the [Fe2S2](2+,+) centers in wild-type and equivalent variants of the highly homologous and structurally characterized Aquifex aeolicus ferredoxin 4 (AaeFd4) using EPR, UV-visible-NIR absorption, CD and variable-temperature MCD, and protein-film electrochemistry. The results indicate that the [Fe2S2](+) centers in the equivalent AaeFd4 and CpFd variants reversibly interconvert between similar valence-localized S = 1/2 and valence-delocalized S = 9/2 forms as a function of pH, with pKa values in the range 8.

An empirical approach for quantifying loop-mediated isothermal amplification (LAMP) using Escherichia coli as a model system.

Loop mediated isothermal amplification (LAMP) is a highly efficient, selective and rapid DNA amplification technique for genetic screening of pathogens. However, despite its popularity, there is yet no mathematical model to quantify the outcome and no well-defined metric for comparing results that are available. LAMP is intrinsically complex and involves multiple pathways for gene replication, making fundamental modelling nearly intractable.

An EPR/HYSCORE, Mössbauer, and resonance Raman study of the hydrogenase maturation enzyme HydF: a model for N-coordination to [4Fe-4S] clusters.

The biosynthesis of the organometallic H cluster of [Fe-Fe] hydrogenase requires three accessory proteins, two of which (HydE and HydG) belong to the radical S-adenosylmethionine enzyme superfamily. The third, HydF, is an Fe-S protein with GTPase activity. The [4Fe-4S] cluster of HydF is bound to the polypeptide chain through only the three, conserved, cysteine residues present in the binding sequence motif CysXHisX(46-53)HisCysXXCys.

Comparative energetics and kinetics of autotrophic lipid and starch metabolism in chlorophytic microalgae: implications for biomass and biofuel production.

Due to the growing need to provide alternatives to fossil fuels as efficiently, economically, and sustainably as possible there has been growing interest in improved biofuel production systems. Biofuels produced from microalgae are a particularly attractive option since microalgae have production potentials that exceed the best terrestrial crops by 2 to 10-fold. In addition, autotrophically grown microalgae can capture CO2 from point sources reducing direct atmospheric greenhouse gas emissions.

Arabidopsis thaliana Nfu2 accommodates [2Fe-2S] or [4Fe-4S] clusters and is competent for in vitro maturation of chloroplast [2Fe-2S] and [4Fe-4S] cluster-containing proteins.

Nfu-type proteins are essential in the biogenesis of iron-sulfur (Fe-S) clusters in numerous organisms. A number of phenotypes including low levels of Fe-S cluster incorporation are associated with the deletion of the gene encoding a chloroplast-specific Nfu-type protein, Nfu2 from Arabidopsis thaliana (AtNfu2). Here, we report that recombinant AtNfu2 is able to assemble both [2Fe-2S] and [4Fe-4S] clusters.

Roles of four conserved basic amino acids in a ferredoxin-dependent cyanobacterial nitrate reductase.

The roles of four conserved basic amino acids in the reaction catalyzed by the ferredoxin-dependent nitrate reductase from the cyanobacterium Synechococcus sp. PCC 7942 have been investigated using site-directed mutagenesis in combination with measurements of steady-state kinetics, substrate-binding affinities, and spectroscopic properties of the enzyme's two prosthetic groups. Replacement of either Lys58 or Arg70 by glutamine leads to a complete loss of activity, both with the physiological electron donor, reduced ferredoxin, and with a nonphysiological electron donor, reduced methyl viologen.

Reversible cycling between cysteine persulfide-ligated [2Fe-2S] and cysteine-ligated [4Fe-4S] clusters in the FNR regulatory protein.

Fumarate and nitrate reduction (FNR) regulatory proteins are O(2)-sensing bacterial transcription factors that control the switch between aerobic and anaerobic metabolism. Under anaerobic conditions [4Fe-4S](2+)-FNR exists as a DNA-binding homodimer. In response to elevated oxygen levels, the [4Fe-4S](2+) cluster undergoes a rapid conversion to a [2Fe-2S](2+) cluster, resulting in a dimer-to-monomer transition and loss of site-specific DNA binding.

Rapid, sensitive and label-free detection of Shiga-toxin producing Escherichia coli O157 using carbon nanotube biosensors.

An electronic platform to detect very small amounts of genomic DNA from bacteria without the need for PCR amplification and molecular labeling is described. The system uses carbon nanotube field-effect transistor (FET) arrays whose electrical properties are affected by minute electrical charges localized on their active regions. Two pathogenic strains of E.

Anaerobic sulfatase-maturating enzyme--a mechanistic link with glycyl radical-activating enzymes?

Sulfatases form a major group of enzymes present in prokaryotes and eukaryotes. This class of hydrolases is unique in requiring essential post-translational modification of a critical active-site cysteinyl or seryl residue to C(alpha)-formylglycine (FGly). Herein, we report mechanistic investigations of a unique class of radical-S-adenosyl-L-methionine (AdoMet) enzymes, namely anaerobic sulfatase-maturating enzymes (anSMEs), which catalyze the oxidation of Cys-type and Ser-type sulfatases and possess three [4Fe-4S](2+,+) clusters.

Characterization of [4Fe-4S]-containing and cluster-free forms of Streptomyces WhiD.

WhiD, a member of the WhiB-like (Wbl) family of iron-sulfur proteins found exclusively within the actinomycetes, is required for the late stages of sporulation in Streptomyces coelicolor. Like all other Wbl proteins, WhiD has not so far been purified in a soluble form that contains a significant amount of cluster, and characterization has relied on cluster-reconstituted protein. Thus, a major goal in Wbl research is to obtain and characterize native protein containing iron-sulfur clusters.

ENDOR spectroscopy shows that guanine N1 binds to [4Fe-4S] cluster II of the S-adenosylmethionine-dependent enzyme MoaA: mechanistic implications.

The S-adenosylmethionine-dependent enzyme MoaA, in concert with MoaC, catalyzes the first step of molybdenum cofactor biosynthesis, the conversion of guanosine 5'-triphosphate (5'-GTP) into precursor Z. A published X-ray crystal structure of MoaA with the substrate 5'-GTP revealed that the substrate might be bound to the unique iron of one of two 4Fe-4S clusters through either or both the amino and N1 nitrogen nuclei. Use of 35 GHz continuous-wave ENDOR spectroscopy of MoaA with unlabeled and (15)N-labeled substrate and a reduced [4Fe-4S](+) cluster now demonstrates that only one nitrogen nucleus is bound to the cluster.

Anaerobic sulfatase-maturating enzymes, first dual substrate radical S-adenosylmethionine enzymes.

Sulfatases are a major group of enzymes involved in many critical physiological processes as reflected by their broad distribution in all three domains of life. This class of hydrolases is unique in requiring an essential post-translational modification of a critical active-site cysteine or serine residue to C(alpha)-formylglycine. This modification is catalyzed by at least three nonhomologous enzymatic systems in bacteria.