Spectroscopic binding studies of novel fluorescent distamycin derivatives

Novel distamycin-porphyrin conjugates were synthesized and their interaction with calf thymus DNA was studied. Minor groove binding of the distamycin part of the molecule was confirmed. The porphyrin part of the conjugates exhibited intercalation and the non-specific electrostatic interaction with the phosphate groups of DNA.     

FT‐IR,FT‐Raman and DFT calculations of the salicylanilide derivate 4‐chloro‐2‐(4‐bromophenylcarbamoyl)phenyl acetate

FT‐IR and FT‐Raman spectra of 4‐chloro‐2‐(4‐bromophenylcarbamoyl)phenyl acetate were recorded and analyzed. The vibrational wavenumbers and corresponding vibrational assignments were examined theoretically using the Gaussian03 set of quantum chemistry codes. The red shift of the NH stretching wavenumber in the infrared (IR) spectrum from the computed wavenumber indicates the weakening of the NH bond resulting in proton transfer to the neighbouring oxygen atom. The simultaneous IR and Raman activations of the CO stretching mode give the charge transfer interaction through a π‐conjugated path. Optimized geometrical parameters of the title compound are in agreement with similar reported structures. From the optimized structure, it is clear that the hydrogen bonding decreases the double bond character of CO bond and increases the double bond character of the C N bonds. The first hyperpolarizability, predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non‐linear optics. The assignments of the normal modes are done by potential energy distribution (PED) calculations. Copyright © 2009 John Wiley & Sons, Ltd.     

The specific heat of seignettoelectric ceramics

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The specific heat of seignettoelectric ceramics

     

Free pyrene probes in gel and fluid membranes: perspective through atomistic simulations

We consider the properties of free pyrene probes inside gel- and fluidlike phospholipid membranes and unravel their influence on membrane properties. For this purpose, we employ atomic-scale molecular dynamics simulations at several temperatures for varying pyrene concentrations. Molecular dynamics simulations show that free pyrene molecules prefer to be located in the hydrophobic acyl chain region close to the glycerol group of lipid molecules. Their orientation is shown to depend on the phase of the membrane. In the fluid phase, pyrenes favor orientations where they are standing upright in parallel to the membrane normal, while, in the gel phase, the orientation is affected by the tilt of lipid acyl chains. Pyrenes are found to locally perturb membrane structure, while the nature of perturbations in the gel and fluid phases is completely different. In the gel phase, pyrenes break the local packing of lipids and decrease the ordering of lipid acyl chains around them, while, in the fluid phase, pyrenes increase the ordering of nearby acyl chains, thus having an opposite effect. Interestingly, this proposes a similarity to effects induced by cholesterol on structural membrane properties above and below the gel-fluid transition temperature. Further studies express a view that the orientational ordering of pyrene is not a particularly good measure of the acyl chain ordering of lipids. While pyrene ordering provides the correct qualitative behavior of acyl chain ordering in the fluid phase, its capability to predict the correct temperature dependence is limited.     

Influence of deposition temperature on amorphous structure of PECVD deposited a-Si:H thin films

The effect of deposition temperature on the structural and optical properties of amorphous hydrogenated silicon (a-Si:H) thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen was under study. The series of thin films deposited at the deposition temperatures of 50–200°C were inspected by XRD, Raman spectroscopy and UV Vis spectrophotometry. All samples were found to be amorphous with no presence of the crystalline phase. Ordered silicon hydride regions were proved by XRD. Raman measurement analysis substantiated the results received from XRD showing that with increasing deposition temperature silicon-silicon bond-angle fluctuation decreases. The optical characterization based on transmittance spectra in the visible region presented that the refractive index exhibits upward trend with increasing deposition temperature, which can be caused by the densification of the amorphous network. We found out that the scale factor of the Tauc plot increases with the deposition temperature. This behaviour can be attributed to the increasing ordering of silicon hydride regions. The Tauc band gap energy, the iso-absorption value their difference were not particularly influenced by the deposition temperature. Improvements of the microstructure of the Si amorphous network have been deduced from the analysis.     

Investigating spectrum of biological activity of 4- and 5-chloro-2-hydroxy-N-[2-(arylamino)-1-alkyl-2-oxoethyl]benzamides

In this study, a series of twenty-two 5-chloro-2-hydroxy-N-[2-(arylamino)-1-alkyl-2-oxoethyl]benzamides and ten 4-chloro-2-hydroxy-N-[2-(arylamino)-1-alkyl-2-oxoethyl]benzamides is described. The compounds were analyzed using RP-HPLC to determine lipophilicity. Primary in vitro screening of the synthesized compounds was performed against mycobacterial, bacterial and fungal strains. They were also evaluated for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The compounds showed biological activity comparable with or higher than the standards isoniazid, fluconazole, penicillin G or ciprofloxacin. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds as well as their structure-activity relationships are discussed.     

Dye decolorisation by laccase immobilised in lens-shaped poly(vinyl alcohol) hydrogel capsules

In this study, laccase (from Trametes versicolor, 8.3 U mg _enz ^?1 ) was used for the decolorisation of Saturn Blue L4G (10 mg L^?1). The efficiency of the decolorisation (ratio between the amount of decolorised dye and initial amount of dye) by a free enzyme was 48 % and the decolorisation rate was determined at 2.11 × 10^?3 mg_dye mg _enz ^?1 min^?1. After immobilisation in lens-shaped poly(vinyl alcohol) hydrogel capsules LentiKats® Biocatalyst (LB) (concentration of immobilised enzyme: 4 mg per g of particles; volume-loading rate of LB: 10 g per 100 mL of medium), the enzyme retained 16.1 % of its original activity (1.34 U mg _enz ^?1 ). Immobilised laccase was used for the dye decolorisation in 130 repeated batch tests with 71 % efficiency (LB activity: 7 × 10^?3 mgdye min^?1 g _LB ^?1 ). In continuous mode (after 716.5 h), the efficiency of the dye decolorisation was 48 % (LB activity: 3.3 × 10^?4 mg_dye min^/?1 g _LB ^?1 ).     

Optical sensing of sulfate by polymethinium salt receptors: colorimetric sensor for heparin

Polymethinium salts based on substituted malondialdehyde have been prepared; the salt with PEG substitution showed high selectivity for sulfate anions and heparin in aqueous medium at physiological condition; intracellular imaging of heparin-rich subcellular compartments was achieved with our polymethinium novel receptor for cancer cell lines.     

Porphyrin-bile acid conjugates: from saccharide recognition in the solution to the selective cancer cell fluorescence detection

This paper describes the preparation and use of conjugates of porphyrins and bile acids as ligands to bind to tumor expressed saccharides. Bile acid-porphyrin conjugates were tested for recognition of saccharides that are typically present on malignant tumor cells. Fluorescence microscopy, in vitro PDT cell killing, and PDT of subcutaneous 4T1 mouse tumors is reported. High selectivity for saccharide cancer markers and cancer cells was observed. This in vivo and in vitro study demonstrated high potential use for these compounds in targeted photodynamic therapy.