Kinetics and dynamics of dissolution/mixing of a high-viscosity liquid phase in a low-viscosity solvent phase

We studied mixing in the initially separated binary mixture of polystyrene/5CB liquid crystal and ternary mixtures of water/surfactant C12E5/polymer PEG system. In both systems the domains of one phase were characterized by a much higher viscosity than the solvent matrix. We demonstrated experimentally that during mixing these domains decrease their size linearly with time without a visible change of the optical contrast (i.e., without a rapid change of their compositions). Computer simulations and a theoretical model explain quantitatively our experimental observations.     

A nonacid degradable linker for solid-phase synthesis

Synthesis and applications of two new nonacid degradable linkers as an alternative to the Wang linker for solid-phase synthesis are described. Resin from linker 2 looks superior to linker 1 in terms of yields for both anchoring of the first building block and cleavage and in terms of higher purity of the final product. Use of linker 2 avoids side reactions associated with the use of Wang resin due to an undesired cleavage during final acid treatment.     

Spectrally resolved fluorescence imaging of human colonic adenomas

Native fluorescence (autofluorescence) of human tissues can be a valuable source of diagnostic information for detecting premalignant and malignant lesions in the human body. Digital imaging of autofluorescence may be useful for localization of such lesions during endoscopic examinations. Tissue fluorescence of 31 adenomatous polyps obtained from 16 patients has been excited in vitro using the 325 nm line of a He-Cd laser. Digital images of the autofluorescence are recorded in six spectral bands. This study provides new data about the spatial distributions of autofluorescence intensities emitted in different spectral bands by colonic adenomatous lesions and normal colonic mucosa. Areas characterized by autofluorescence intensity lower than in normal mucosa are found for a majority of the polyps under study. The observed patterns of spatial distribution differ for the different spectral bands and for different polypoid lesions. No inverse correlation is found between the emission intensity and the thickness of colonic mucosa. The results indicate the spectral bands most useful for diagnostic applications and demonstrate the complexity of the optical processes involved in shaping both the spectra and intensities of the autofluorescence.     

Determination of Heavy Polycyclic Aromatic Hydrocarbons (PAH) in Drinking Water,Ambient Air,Soils, Sediments and Food Stuffs by HPLC Method with Fluorescence Detection

The methods for the determination of some heavy PAH in different objects by HPLC method with fluorescence detection have been developed. The following conditions for the separation of PAH have been chosen:The column 150 mm length, internal diameter 2.1 mm filled by reversible-phase sorbent Zorbax ODS (5 μ),mobile phase acetonutrile/water (80:20), the injected volume of sample concentrate 10 μ L, the velocity of mobile phase 200 μ L.min. The excitation region is 290-300 nm, the emission one is 350-420 nm. Under condition chosen the limit of detection are 5 pg for benz(a)pyrene,10 pg for pyrene and chrysene3 pg for benz(k)fluoranthene, and 20 pg for anthracene. The dynamic range is 3 order of magnitude. The reproducibility of peak highs is better than 5%.     

Vibrational spectroscopy of implants

The results of systematic spectral studies of polymers in ophthalmology are presented. The spectral criteria of selection of intraocular lens (IOL; implants of long service in an organism have been defined for poly(methylphenylsiloxane). Non-inflammatory implantation of IOL, when the manufacturing of lenses is performed under spectral control at several stages, has been realized. New siloxane–polyurethane block copolymers promising for ophthalmology have been studied and passivated surfaces have been obtained.     

4,5-Bis(arylethynyl)-1,2,3-triazoles—A New Class of Fluorescent Labels: Synthesis and Applications

Cu-catalyzed 1,3-dipolar cycloaddition of ethyl 2-azidoacetate to iodobuta-1,3-diynes and subsequent Sonogashira cross-coupling were used to synthesize a large series of new triazole-based push–pull chromophores: 4,5-bis(arylethynyl)-1H-1,2,3-triazoles. The study of their optical properties revealed that all molecules have fluorescence properties, the Stokes shift values of which exceed 150 nm. The fluorescent properties of triazoles are easily adjustable depending on the nature of the substituents attached to aryl rings of the arylethynyl moieties at the C4 and C5 atoms of the triazole core. The possibility of 4,5-bis(arylethynyl)-1,2,3-triazoles’ application for labeling was demonstrated using proteins and the HEK293 cell line. The results of an MTT test on two distinct cell lines, HEK293 and HeLa, revealed the low cytotoxicity of 4,5-bis(arylethynyl)triazoles, which makes them promising fluorescent tags for labeling and tracking biomolecules.     

Preparation,Characterization and In Vitro Biological Activities of New Diphenylsulphone Derived Schiff Base Ligands and Their Co(II) Complexes

The present work describes the chemical preparation of Schiff bases derived from 4,4′-diaminodiphenyl sulfone (L₁–L₅) and their Co(II) metal complexes. The evaluation of antimicrobial and anticancer activities against MCF-7 cell line and human lung cancer cell line A-549 was performed. The aforementioned synthesized compounds are characterized by spectroscopic techniques and elemental analysis confirms successful synthesis. The results from the above analytical techniques revealed that the complexes are in an octahedral geometry. The antimicrobial activity of the synthesized Schiff base ligands and their metal complexes under study was carried out by using the agar well diffusion method. The ligand and complex interactions for biological targets were predicted using molecular docking and high binding affinities. Further, the anticancer properties of the synthesized compounds are performed against the MCF-7 cell line and human lung cancer cell line A-549 using adriamycin as the standard drug.     

Kinetics and Energetics of Intramolecular Electron Transfer in Single-Point Labeled TUPS-Cytochrome c Derivatives

Electron transfer within and between proteins is a fundamental biological phenomenon, in which efficiency depends on several physical parameters. We have engineered a number of horse heart cytochrome c single-point mutants with cysteine substitutions at various positions of the protein surface. To these cysteines, as well as to several native lysine side chains, the photoinduced redox label 8-thiouredopyrene-1,3,6-trisulfonate (TUPS) was covalently attached. The long-lived, low potential triplet excited state of TUPS, generated with high quantum efficiency, serves as an electron donor to the oxidized heme c. The rates of the forward (from the label to the heme) and the reverse (from the reduced heme back to the oxidized label) electron transfer reactions were obtained from multichannel and single wavelength flash photolysis absorption kinetic experiments. The electronic coupling term and the reorganization energy for electron transfer in this system were estimated from temperature-dependent experiments and compared with calculated parameters using the crystal and the solution NMR structure of the protein. These results together with the observation of multiexponential kinetics strongly support earlier conclusions that the flexible arm connecting TUPS to the protein allows several shortcut routes for the electron involving through space jumps between the label and the protein surface.