Increased Crystallization of CuTCNQ in Water/DMSO Bisolvent for Enhanced Redox Catalysis

Controlling the kinetics of CuTCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) crystallization has been a major challenge, as CuTCNQ crystallizing on Cu foil during synthesis in conventional solvents such as acetonitrile simultaneously dissolves into the reaction medium. In this work, we address this challenge by using water as a universal co-solvent to control the kinetics of crystallization and growth of phase I CuTCNQ. Water increases the dielectric constant of the reaction medium, shifting the equilibrium toward CuTCNQ crystallization while concomitantly decreasing the dissolution of CuTCNQ. This allows more CuTCNQ to be controllably crystallized on the surface of the Cu foil. Different sizes of CuTCNQ crystals formed on Cu foil under different water/DMSO admixtures influence the solvophilicity of these materials. This has important implications in their catalytic performance, as water-induced changes in the surface properties of these materials can make them highly hydrophilic, which allows the CuTCNQ to act as an efficient catalyst as it brings the aqueous reactants in close vicinity of the catalyst. Evidently, the CuTCNQ synthesized in 30% (v/v) water/DMSO showed superior catalytic activity for ferricyanide reduction with 95% completion achieved within a few minutes in contrast to CuTCNQ synthesized in DMSO that took over 92 min.

Chromatic Toxicity Bioassay of Water through Bacterial Ferricyanide Reduction

Water quality assessment demands a precise anatomization of specimens that comply with acclaimed water purity standards. Today, the growing number of toxicants and their synergistic consequences make it necessary to develop general toxicity assays able to examine and determine water pollution. Contemporary general toxicity methods hinder specimen analysis due to their prolonged operation protocols. Also, the equipment involved is very expensive that not everyone can afford it. In an effort to resolve these drawbacks, a quick and cost effective toxicity bioassay based on chromatic changes related to bacterial ferricyanide reduction is introduced here. E.coli cells (Model Bacteria) were stably confined on four supports: Cellulose-based Paper Discs, Silica 60, Polystyrene, and Acrylic Beads, which remained useful for a long period at -20ºC. Copper was used as a model toxic agent to perform Bioassay Assessment. Chromatic changes related to bacterial ferricyanide reduction were determined by visual inspection. Cellulose Paper Discs, Polystyrene, and Acrylic beads showed good results and better viability, while Silica 60 proved itself as a weak support and resulted in poor viability.

A 35-fold enhancement in photocurrent generation of Synechocystis sp. PCC 6803 by outer membrane deprivation

Biophotovoltaics (BPV) is an emerging technology developed to utilize reducing equivalents produced by photosynthetic organisms. It generates electrical power by exploiting a phenomenon called extracellular electron transfer (EET), where reducing equivalents are transferred extracellularly to exogenous electron acceptors. Although cyanobacteria have been extensively studied in BPV because of their high photosynthetic activity and ease of handling, their extremely low EET activity remains a limitation. In this study, we achieved a 35-fold enhancement in photocurrent generation of the cyanobacterium Synechocystis sp. PCC 6803 by deprivation of the outer membrane, where electrons are suggested to stem from NADPH; this, along with a significantly higher rate of exogenous ferricyanide reduction, verified that low permeability of the outer membrane contributues to low cyanobacterial EET activity. Moreover, outer membrane deprivation enhanced extracellular derivation of reducing equivalents serving as respiratory substrates for other heterotrophic bacteria, making it promising and useful for effective derivation of reducing equivalents.

Evaluation of Reducing Ability and Antioxidant Activity of Fruit Pomace Extracts by Spectrophotometric and Electrochemical Methods

The component profiles of apricot, grape, and black currant pomace extracts have been analyzed using HPLC coupled to diode-array detection and tandem mass spectrometry (HPLC-DAD-MS). The predominant components in grape, apricot, and black currant pomace extracts were phenolic acids and flavonols. The redox behavior of apricot, black currant, and grape pomace water extracts was evaluated by means of cyclic voltammetry. Also, individual substances mainly present in the extracts were analyzed. The results of electrochemical testing were compared to traditional chemical techniques of potassium ferricyanide reduction (FRAP) and phosphomolybdenum assay, and fair agreement was established. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assays were applied in order to estimate antioxidant activity. The reducing power of the grape extract was found to be higher than that of the apricot and black currant extracts in both potassium ferricyanide reduction (FRAP) and phosphomolybdenum methods.

Loss of multiple enzyme activities due to the human genetic variation P284T in NADPH cytochrome P450 oxidoreductase

Cytochromes P450 located in the endoplasmic reticulum require NADPH cytochrome P450 oxidoreductase (POR) for their catalytic activities. Mutations in POR cause multiple disorders in humans related to the biosynthesis of steroid hormones and also affect drug-metabolizing cytochrome P450 activities. Here we are reporting the effects of a POR genetic variant P284T which is located in the hinge region of POR that is necessary for the flexibility of domain movements. Human wild-type and P284T mutant of POR, as well as cytochrome P450 proteins, were expressed in bacteria, purified and then reconstituted in liposomes for enzyme kinetic assays. Quality of POR proteins was checked by cytochrome c, ferricyanide and tetrazolium dye reduction assay and measurements flavin content. We found that for the P284T variant of POR the cytochrome c reduction activity was reduced to 47% of the WT and MTT reduction was reduced to only 15% of the WT. No impact on ferricyanide reduction activity was observed, but a severe loss of CYP19A1 (aromatase) activity was observed (9% of WT). In the assays of drug metabolizing cytochrome P450 enzymes, the P284T variant of POR showed 26% activity for CYP2C9, 44% activity for CYP2C19, 23% activity for CYP3A4 and 44% activity in CYP3A5 assays compared to the WT POR. These results indicate a severe effect on several cytochrome P450 activities due to the P284T variation in POR which suggests a negative impact on both the steroid as well as drug metabolism in the individuals carrying this variation.