In Vitro Study of Ketoprofen and Indapamide Used in Multidrug Therapy: 1H-NMR Analysis

ABSTRACT

Interaction of ketoprofen (KP, a nonsteroidal anti-inflammatory drug) and indapamide (IDP, a thiazide-related diuretic) with human serum albumin (HSA) in low-affinity binding sites (LAS) and competition between these medicines used in multidrug therapy have been studied by proton nuclear magnetic resonance (¹H-NMR) spectroscopy.

The analysis of chemical shifts, Δσ (ppm), of drug proton resonances and the values of the association constant, K_a [M^?1], were used to estimate the effect of IDP and KP on the KP–HSA and IDP–HSA complexes, respectively. The results showed the changes in the affinity of human serum albumin toward the drug with different mechanisms of action (KP and IDP) and the competition in the binding to HSA.     

On the structural formation of albumin

A microstructural analysis of the human serum albumin (HSA) samples dehydrated on a glass substrate from solutions with different concentrations of protein has been performed. The structuring effect of salt (NaCl) on the variations in the morphology of HSA interfaces has been shown experimentally. The substantiation of some structural effects has been given by taking into consideration the supramolecular organization and the polyelectrolyte nature of the protein molecule.

     

Pressure induced changes in proteins studied in the diamond anvil cell with Raman spectroscopy

Abstract

The pressure induced denaturation of serum albumin and lysozyme is studied. Preliminary results suggest that the changes induced in serum albumin are reversible below 10 kbar.     

Conformation transitions of blood proteins under influence of physical factors on microwave dielectric method

In this article, the influence of γ-irradiation and temperature on albumin and fibrinogen conformation and dielectric properties of protein solutions have been studied by the microwave dielectric method. Both the values of the real part ε′ (dielectric permittivity) and the imaginary part ε″ (dielectric losses) of the complex dielectric permittivity of the aqueous solution of bovine serum albumin and human fibrinogen as functions of temperature and γ-irradiation dose have been obtained. The time of dielectric relaxation of water molecules in the protein solutions was calculated. The hydration of the albumin and fibrinogen molecules was determined. The temperature dependencies of hydration are non-monotonous and have a number of characteristic features at the temperatures 30-34 and 44-47 °C for serum albumin, and 24 and 32 °C for fibrinogen.     

FTIR‐ATR Study of pH Effects on Egg Albumin Secondary Structure

Abstract

The pH effects on the secondary structures of egg albumin were investigated using Fourier transform infrared–attenuated total reflection (FTIR‐ATR) technique with a single‐bounce diamond crystal. The albumin was first denatured in a series of solutions with pH ranging from 1 to 12. The albumin film was then cast on the ATR crystal from the albumin solution for the IR spectrum collection. Significant secondary structure spectral differences were observed for these films. The findings are presented in terms of the shape and position of the albumin amide I band between 1600 and 1700 cm^?1.     

Ellipsometry studies of albumin films on tantalum oxide and SiO2

The adsorption of (1) bovine serum albumin in acetate buffer, (2) albumin followed by glutaraldehyde crosslinking, (3) albumin followed by exposure to an albumin/glutaraldehyde solution, and (4) albumin after the surface was subjected to treatment (3), has been studied using Ta oxide/Ta chips and SiO₂/Si wafers as substrates. The films were washed, air dried and measured in air using an automatic laser ellipsometer, 6328 Å. The films formed from treatment (3) and treatment (4) have a lower refractive index and are thicker than films formed from treatment (1) and treatment (2). The adsorption of albumin on SiO₂/Si wafers seems to be slower than that on the Ta oxide/Ta surfaces.     

Molecular mechanism investigation on the interaction of Clothianidin with human serum albumin

Abstract

With the widespread application of neonicotinoid insecticides, Clothianidin has received much attention due to the potential harm to human health and ecological environment. However, the mechanism of Clothianidin's underlying toxicity to organisms remains unclear. In this work, the interaction between Clothianidin and human serum albumin was investigated and the intrinsic fluorescence of human serum albumin got quenched via static mechanisms upon the addition of Clothianidin. The binding constants between Clothianidin and human serum albumin at three different temperature were obtained to be 3.543?×?10⁴, 2.995?×?10⁴, and 2.490?×?10⁴ M^?1, respectively. Based on the van't Hoff equation, the thermodynamic parameters, ΔH⁰ and ΔS⁰ were estimated to be ?53.885?KJ mol^?1 and ?110.535?J mol^?1K^?1, respectively. A single binding site was predicted from the binding constants at different temperatures by multiple spectroscopic techniques and the negative values of ΔH⁰ and ΔS⁰ indicated the binding of human serum albumin with Clothianidin was driven by hydrogen bonds or van der Waals forces. Furthermore, the loose and unfolded secondary structure of human serum albumin along with the addition of clothianidin had been observed through ultraviolet-visible absorption and circular dichroism spectra. In addition, it was also found that Clothianidin had polar effects of structural microenviroment not only on Trp but also Tyr residues from synchronous fluorescence analysis. This study illuminates the molecular mechanism of the interaction between human serum albumin and clothianidin for the first time and helps to construct a specific pesticide biosensor system of human health.     

Determination of Microamounts of Proteins by Resonance Light Scattering with Copper Phthalocyanine Tetrasulfonic Acid

Abstract

Based on the strong enhancement effect of proteins on the resonance light scattering of copper phthalocyanine tetrasulfonic acid, a method for the determination of microamounts of proteins has been developed. Under the experimental conditions (2.0×10^?6 mol/L copper phthalocyanine tetrasulfonic acid, pH 2.60, ionic strength 0.001 mol/L NaCl), the linear range of this assay is 0.06–4.0 µg/mL for bovine serum albumin (BSA), 0.1–2.0 µg/mL for human serum albumin (HSA), 0.0–2.0 µg/mL for human γ‐IgG, and 0.2–6.0 µg/mL for ovalbumin. The detection limits (3δ) are 16.8 ng/mL for BSA, 23.4 ng/mL for HSA, 37.6 ng/mL for human γ‐IgG, and 48.3 ng/mL for ovalbumin, respectively. This method has been applied to the analysis of total proteins in human serum samples collected from the hospital, and the results were in good agreement with those reported by the hospital.     

Effect of Temperature on Re-entrant Condensation of Globular Protein in Presence of Tri-valent Ions

Globular proteins play several essential roles in functioning different mechanisms of the living organisms, and the stability of such protein molecules in an aqueous solution is strongly affected by multivalent ions. In this article, we have systematically studied the effect of temperature (between 5 and 25ºC) on the re-entrant condensation behaviour of bovine serum albumin (BSA) in the presence of trivalent ions, Yttrium (Y³⁺), and Lanthanum (La³⁺). The effect of temperature is explained considering the optical properties of the protein, i.e., from the optical absorption and emission behaviours. The absorption in the visible region and the fluorescence emission of BSA becomes maximum at the lowest temperature. The decrement of mobility at lower temperature is responsible for fluorescence enhancement. Moreover, the activation energy of the turbid or viscus phase of the BSA protein under re-entrant condensation is enhanced in comparison with the transparent phase and the corresponding energy value is estimated from the fluorescence study.

     

Solvothermal synthesis of nitrides

Abstract

III-V nitrides are large band-gap semiconductors. They are very promising materials for opto-electronic and microelectronic applications.

The present paper deals with a new process for preparing nitrides. Two nitrides, gallium nitride (GaN) and aluminium nitride (AlN), have been synthesiaed through a solvothermal route. This process uses ammonia in supercritical conditions as solvent and metals as source of gallium and aluminium. Moreover, an additive is used to improve the nitridation of the metals.

The resulting microcrystallites of nitrides have been charactensed by X-ray diffraction and the morphology has been observed by scanning Electron Microscopy.     

Polarized Infrared and Raman Spectra and Ab-initio Calculations of Benzotriazole

Abstract

The i. r. spectra of benzotriazole have been measured from 4000 to 60 cm^?1: polarized spectra of single crystals have been also obtained. The Raman spectra of polycrystalline samples and solutions have been investigated. The structural parameters and vibrational frequencies have been determined from ab-initio Hartree-Fock gradient calculations using the 6–31G* basis set. A detailed arsignment of most of the observed bands has been proposed on the basis of the i. r. dichroism, Raman polarization data and frequency calculations.

     

Plasma-chemical reactor based on a low-pressure pulsed arc discharge for synthesis of nanopowders

A reactor for producing nanopowders in the plasma of a low-pressure arc discharge has been developed. As a plasma source, a pulsed cold-cathode arc evaporator has been applied. The design and operating principle of the reactor have been described. Experimental data on how the movement of a gaseous mixture in the reactor influences the properties of nanopowders have been presented.

     

Intracavity Electronic Absorption Spectra of MoO and WO Molecules in the Visible Region

Absorption electronic spectra of MoO and WO molecules have been investigated by a intracavity laser technique in the region 550–800 run. New features have been discovered.

As for MoO molecule the rotational analysis of the four bands have been carried out for the first time. Two of these bands were referred to 0–0 transitions arisen from the new (probable triplet) low-lying electronic state, two other bands were referred to transitions arisen from excited components of X⁵II ground state.

As for WO molecule the rotational analysis of 0–0 and 1–0 bands represented A-X and B-X systems have been carried out for the first time. The new band has been discovered which has been referred to new electronic transition.

Molecular constants of new states of both molecules studied have been evaluated.     

Vibrational Assignment of N-Phenylphthalimide and 15N-Phenylphthalimide

Abstract

The i.r. spectra of N-phenylphthalimide and ¹⁵N-phenylphthalimide have been measured in 4000–100 cm^?1 frequency range as KBr and polyethylene pellets and as chloroform solutions. The Raman spectra (4000–50) cm^?1 of microcrystalline powder of the of the same compounds have also been investigated.

A detailed assignment of most of the observed frequencies has been proposed on the basis of the group vibrational concept, isotopic shift data and analogies with the spectra of related molecules. Some literature data have been discussed and some frequencies are reassigned.     

Estimation of the Electron–Phonon Coupling Constants for Graphene and Metallic and Nonmetallic Substrates

Two modes of graphene–substrate interaction have been considered: a weak van der Waals bond and a strong covalent bond. The Lennard–Jones potential and Harrison bond-orbital method are used in the former and latter cases, respectively. Analytical expressions for the electron–phonon interaction constants, which contain only two parameters (binding energy E _B for graphene and a substrate and distance d between them) have been obtained. The constants have been calculated for metallic, semiconductor, and dielectric substrates.

     

High-temperature heat capacity of YBiGeO5 and GdBiGeO5 in the range 373–1000 K

The oxide YBiGeO₅ and GdBiGeO₅ compounds have been synthesized by solid-phase synthesis. The high-temperature heat capacity has been measured using differential scanning calorimetry in the range 373–1000 K. The results were used to calculate the thermodynamic properties (the change in the enthalpy and entropy).

     

Flexible Electrode Made of Graphene and Few-Layer Graphite

A method of obtaining graphene oxide from Hummers-modified natural flake graphite with subsequent synthesis of reduced graphene and few-layer graphite has been suggested. The structure and electrical performance of the synthesized material have been studied. The feasibility of making a high-capacitance flexible electrode using polyethylene substrates covered by a conductive ink has been demonstrated.

     

Location of self-interstitial atoms in boron-implanted silicon by means of rutherford backscattering of channelled ions

Abstract

For locating self-interstitial atoms in silicon by means of Rutherford backscattering of channelled ions, boron has been implanted at room temperature and at the temperature of liquid nitrogen. The employed implantation doses were 2. 10¹⁴ cm^?2 and 7. 10¹³ cm^?2, respectively. The experiments have been performed at 300 K and at 120 K to reduce ionization-stimulated annealing. The beam of 1.4 MeV He⁺-ions was highly collimated.

To obtain the configuration of implantation-induced self-interstitial atoms symmetry considerations have been performed.

The location experiments presented indicate the existence of isolated self-interstitial atoms in silicon. Under the conditions of these experiments the interstitial atoms assume a (110) split configuration of orthorhombic symmetry.     

Low temperature,high pressure Raman study of SbSBr

Abstract

We have measured the Raman spectra of the quasi-one-dimensional crystal SbSBr as a function of pressure at 295, 70, 37 and 25 K.

The pressure coefficients of the observed Raman modes have been determined and used to distinguish inter-from intrachain modes. Spectral features characteristic of the ferroelectric phase have been attributed to impurities or lattice imperfections and not to the presence of the ferroelectric phase, providing indication that the para-to ferroelectric phase transition occurs below 25 K.     

Diffraction study of actinides under pressure

Abstract

Uranium and thorium have sufficiently low radioactive dose rates to allow their study at synchrotrons and neutron facilities. Correspondingly, numerous compounds of these two actinides have been studied under pressure by synchrotron x-ray diffraction. The maximum pressures reached were on the order of 60-80 GPa, and 300 GPa in one case.

The situation is much more difficult for all other actinides. Their high level of radioactivity has up to now prevented their study at synchrotrons, except in a few special cases. In contrast, all actinide metals available in sufficient quantities, and a large number of compounds of highly radioactive actinides, have been studied in highpressure laboratory facilities.

Recent examples of in situ high pressure x-ray diffraction work will be described.