New Insight on Biological Interaction Analysis: New Nanocrystalline Mixed Metal Oxide SPME Fiber for GC-FID Analysis of BTEX and Its Application in Human Hemoglobin-Benzene Interaction Studies

Nanocrystalline mixed metal oxides (MMO) of various metal cations were synthesized and were used for coating a piece of copper wire as a new high sensitive solid phase micro extraction (SPME) fiber in extraction and determination of BTEX compounds from the headspace of aqueous samples prior to GC-FID analysis. Under optimum extraction conditions, the proposed fiber exhibited low detection limits, and quantification limits, good reproducibility, simple and fast preparation method, high fiber capacity and high thermal and mechanical durability. These are some of the most important advantages of the new fiber. The proposed fiber was used for human hemoglobin upon interaction with benzene. Binding isotherm, Scatchard and Klotz logarithmic plots were constructed using HS-SPME-GC data, accurately. The obtained binding isotherm analyzed using Hill method. The Hill parameters have been obtained by calculating saturation parameter from the ratio of measured chromatographic peak areas in the presence and absence of hemoglobin. In this interaction, Hill coefficient and Hill constant determined as (n_H = 6.14 and log K_H = 6.47) respectively. These results reveal the cooperativity of hemoglobin upon interaction with benzene.     

Molecular Modelling of The Mechanism of Action of Organic Clay-Swelling Inhibitors

Abstract

It is well known that the sodium smectite class of clays swells macroscopically in contact with water, whereas under normal conditions the potassium form does not. In recent work using molecular simulation methods, we have provided a quantitative explanation both for the swelling behaviour of sodium smectite clays and the lack of swelling of potassium smectites [1]. In the present paper, we apply similar modelling methods to study the mechanism of inhibition of clay-swelling by a range of organic molecules.

Experimentally, it is known that polyalkylene glycols (polyethers) of intermediate to high relative molecular mass are effective inhibitors of smectite clay swelling. We use a range of atomistic simulation techniques, including Monte Carlo and molecular dynamics, to investigate the interactions between a selection of these compounds, water, and a model smectite clay mineral. These interactions occur by means of organised intercalation of water and organic molecules within the galleries between individual clay layers.

The atomic interaction potentials deployed in this work are not as highly optimised as those used in our clay-cation-water work [1]. Nevertheless, our simulations yield trends and results that are in qualitative and sometimes semi-quantitative agreement with experimental findings on similiar (but not identical) systems. The internal energy of adsorption of simple polyethers per unit mass on the model clay is not significantly different from that for water adsorption; our Monte Carlo studies indicate that entropy is the driving force for the sorption of the simpler organic molecules inside the clay layers: a single long chain polyethylene glycol can displace a large number of water molecules, each of whose translational entropy is greatly enhanced when outside the clay. Hydrophobically modified polyalkylene glycols also enjoy significant van der Waals interactions within the layers which they form within the clay galleries.

In conjunction with experimental studies, our work furnishes valuable insights into the relative effectiveness of the compounds considered and reveals the generic features that high performance clay-swelling inhibitors should possess. For optimal inhibitory activity, these compounds should be reasonably long chain linear organic molecules with localised hydrophobic and hydrophilic regions along the chain. On intercalation of these molecules within the clay layers, the hydrophobic regions provide an effective seal against ingress of water, while the hydrophilic ones enhance the binding of the sodium cations to the clay surface, preventing their hydration and the ensuing clay swelling.     

The inhibitory effect of ethylenediamine on mushroom tyrosinase

The inhibitory effect of ethylenediamine on both activities of mushroom tyrosinase (MT) at 20 °C in a 10 mM phosphate buffer solution (pH 6.8), was studied. L-DOPA and L-tyrosine were used as substrates of catecholase and cresolase activities, respectively. The results showed that ethylenediamine competitively inhibits both activities of the enzyme with inhibition constants (K(i)) of 0.18±0.05 and 0.14±0.01 μM for catecholase and cresolase respectively, which are lower than the reported values for other MT inhibitors. For further insight a docking study between tyrosinase and ethylenediamine was performed. The docking simulation showed that ethylenediamine binds in the active site of the enzyme near the Cu atoms and makes 3 hydrogen bonds with two histidine residues of active site.     

Impacts of dynamic degradation on the morphological and mechanical characterisation of porous magnesium scaffold

Biomechanics and Modeling in Mechanobiology - This study employs a computational approach to analyse the impact of morphological changes on the structural properties of biodegradable porous Mg...     

Blockchain based secure,efficient and coordinated energy trading and data sharing between electric vehicles

Cluster Computing - In this study, a secure and coordinated blockchain based energy trading system for Electric Vehicles (EVs) is presented. The major goals of this study are to provide secure and...     

Kinetics and mechanism of thermal degradation of pentose- and hexose-based carbohydrate polymers

This work aims at study of thermal degradation kinetics and mechanism of pentose- and hexose-based carbohydrate polymers isolated from Plantago ovata (PO), Salvia aegyptiaca (SA) and Ocimum basilicum (OB). The analysis was performed by isoconversional method. The materials exhibited mainly two-stage degradation. The weight loss at ambient-115°C characterized by low activation energy corresponds to loss of moisture. The kinetic triplets consisting of E, A and g(α) model of the materials were determined. The major degradation stage represents a loss of high boiling volatile components. This stage is exothermic in nature. Above 340°C complete degradation takes place leaving a residue of 10-15%. The master plots of g(α) function clearly differentiated the degradation mechanism of hexose-based OB and SA polymers and pentose-based PO polymer. The pentose-based carbohydrate polymer showed D(4) type and the hexose-based polymers showed A(4) type degradation mechanism.     

Probing the biological evaluations of a new designed Pt(II) complex using spectroscopic and theoretical approaches: human hemoglobin as a target

In recent years, using heavy metal compounds such as platinum as anticancer agent is one of the common ways in chemical therapy. In this study, a new anticancer compound of glycine derivatives of Pt(II) complex (amyl-glycine1, 10-phenanthroline Platinum nitrate) was designed, and the biological effects of this novel compound on the alterations in the function and structure of human hemoglobin (Hb) at different temperatures of 25 and 37°C were assessed by applying various spectroscopic (fluorescence and circular dichroism (CD)) and theoretical methods. Fluorescence data indicated the strong ability of Pt(II) complex to quench the intrinsic fluorescence of Hb. The binding constant, number of binding sites, and thermodynamic parameters at two temperatures were calculated, and the results indicated the major possibility of occurring van der Waals force or hydrogen bond interactions in the Pt(II) complex–Hb interaction. For evaluating the alteration of secondary structure of Hb upon interaction with various concentrations of complex, far-UV CD spectra were used and it was observed that in high dose of complex, significant changes were occurred which is indicative of some side effects in overdosing of this complex. On the other hand, the molecular docking results illustrate that are well in agreement in obtaining data with spectroscopy. Above results suggested that using Pt(II) complex as an anticancer agent, model drug in high-dose usage might cause some disordering in structure and function of Hb as well as improve understanding of the side effects of newly designed metal anticancer drugs undergoing.     

Four mixed-ligands lead(II) complexes based on 8-hydroxyquinolin (8-HQuin), [Pb(8-Quin)X]; X = 4-pyridinecarboxylate, acetate, thiocyanate and nitrate; structural and thermal studies

Lead(II) 8-hydroxychinolate complexes (8-Quin) containing four different anions, [Pb(8-Quin)X]; X = 4-pyridinecarboxylate (1), acetate (2), thiocyanate (3) and nitrate (4), have been synthesized and characterized by elemental analysis, IR-, ¹H NMR- and ¹³C NMR-spectroscopy. All these compounds were structurally characterized by single-crystal X-ray diffraction. The thermal stabilities of compounds 1–4 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The results show the influence of different counter-ions to form dimers in compound 2, one-dimensional polymer in compound 4 and two-dimensional polymer in compounds 1 and 3.