Single-molecular-level study of claudin-1-mediated adhesion

Claudins are proteins that are selectively expressed at tight junctions (TJs) of epithelial cells where they play a central role in regulating paracellular permeability of solutes across epithelia. However, the role of claudins in intercellular adhesion and the mechanism by which they regulate the diffusion of solutes are poorly understood. Here, using single molecule force spectroscopy, the kinetic properties and adhesion strength of homophilic claudin-1 interactions were probed at the single-molecule level. Within the range of tested loading rates (10(3)-10(5) pN/s), our results showed that homophilic claudin-1 interactions have a reactive compliance of 0.363 +/- 0.061 nm and an unstressed dissociation rate of 1.351 +/- 1.312 s-1. This is more than 100-fold greater than that of E-cadherin. The weak and short-lived interactions between claudin-1 molecules make them highly unstable and dynamic in nature. Such a dynamic interaction is consistent with a model where breaking and resealing of TJ strands regulate the paracellular diffusion of solutes.     

Novel 1,3,4‐Oxadiazole Derivatives of Dihydropyrimidinones: Synthesis,Anti‐Inflammatory,Anthelmintic, and Antibacterial Activity Evaluation

The present study depicts synthesis of a series of some novel 5‐(5‐(aryl)‐1,3,4‐oxadiazol‐2‐yl)‐3,4‐dihydro‐6‐methyl‐4‐styrylpyrimidin‐2(1H)‐one derivatives. All the newly synthesized compounds were characterized by FTIR, ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. The compounds were evaluated for their in vivo anti‐inflammatory activity by the carrageenan‐induced rat paw edema method. The compounds were also screened for their anthelmintic activity on Indian earthworms and antibacterial activity against some gram positive and gram negative strains of bacteria. This pharmacological activity evaluation revealed that, among all the compounds screened, compounds 4b and 4c were found to have promising anti‐inflammatory activity. Interestingly, compounds 4b , 4c , and 4i exhibited appreciable anthelmintic property, while compounds 4c , 4g , and 4h showed leading antibacterial activity against the selected pathogenic strains of bacteria.     

Cell adhesion properties on photochemically functionalized diamond

The biocompatibility of diamond was investigated with a view toward correlating surface chemistry and topography with cellular adhesion and growth. The adhesion properties of normal human dermal fibroblast (NHDF) cells on microcrystalline and ultrananocrystalline diamond (UNCD) surfaces were measured using atomic force microscopy. Cell adhesion forces increased by several times on the hydrogenated diamond surfaces after UV irradiation of the surfaces in air or after functionalization with undecylenic acid. A direct correlation between initial cell adhesion forces and the subsequent cell growth was observed. Cell adhesion forces were observed to be strongest on UV-treated UNCD, and cell growth experiments showed that UNCD was intrinsically more biocompatible than microcrystalline diamond surfaces. The surface carboxylic acid groups on the functionalized diamond surface provide tethering sites for laminin to support the growth of neuron cells. Finally, using capillary injection, a surface gradient of polyethylene glycol could be assembled on top of the diamond surface for the construction of a cell gradient.     

Control over C-O and C-C bond formation: ruthenium catalyzed regiospecific addition of carboxylic acid to alkyne and stereoselective dimerization of alkyne

A cationic ruthenium(II) complex, [Ru(PPh₃)₂(CH₃CN)₃Cl][BPh₄] (1), has been found to be an effective catalyst for stereoselective dimerization of alkynes in the presence of a base, and for regiospecific addition of carboxylic acids to alkynes in presence of the Lewis acid, BF₃·Et₂O.     

Efficient Synthesis,Characterization, In Vitro Antibacterial and Antifungal Activity Study and Computational Tool for Prediction of Molecular Properties of Some Novel Schiff's Base via Betti's Protocol and Azetidinones

Series of new substituted pyrazolone derivatives via Betti's condensation reaction of pyrazolone and different aldehydes has been reported successfully under ambient reaction conditions. The structural elucidation of newly synthesized compounds was done using analytical and spectroscopic tools such as elemental analysis, ¹H NMR, ¹³C NMR, and mass spectroscopy. Physicochemical parameters, toxicity profiles and drug likeness properties were studied using various bioinformaticals tools like Osiris and molinspiration. These results viz., the good correlations between the inhibitory activities and the computational values make the molecules available for future protein–ligand interaction studies. It further provided useful information in understanding the structural and chemical features of the drug in designing and finding new potential inhibitors.     

Synthesis of Novel 3‐(3‐(5‐Methylisoxazol‐3‐yl)‐7H‐[1,2,4]Triazolo [3,4‐b][1,3,4]Thiadiazin‐6‐yl)‐2H‐Chromen‐2‐Ones

A novel series of coumarin substituted triazolo‐thiadiazine derivatives were designed and synthesized by using 5‐methyl isoxazole‐3‐carboxylic acid ( 1 ), thiocarbohydrazide ( 2 ), and various substituted 3‐(2‐bromo acetyl) coumarins ( 4a , 4b , 4c , 4e , 4d , 4f , 4g , 4h , 4i , 4j ). Fusion of 5‐methyl isoxazole‐3‐carboxylic acid with thiocarbohydrazide resulted in the formation of the intermediate 4‐amino‐5‐(5‐methylisoxazol‐3‐yl)‐4H‐1,2,4‐triazole‐3‐thiol ( 3 ). This intermediate on further reaction with substituted 3‐(2‐bromo acetyl) coumarins under simple reaction conditions formed the title products 3‐(3‐(5‐methylisoxazol‐3‐yl)‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl‐2H‐chromen‐2‐ones ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j ) in good to excellent yields. All the synthesized compounds were well characterized by physical, analytical, and spectroscopic techniques.     

Studies of synthesis, structural features of Cu(I) thiophene-2-thiocarboxylates and unprecedented desulfurization of Cu(II) thiocarboxylate complexes

Thiophene-2-thiocarboxylate complexes of Cu(I), [(Ph(3)P)(2)Cu(SCOth)] (1) and H[(Ph(3)P)(2)Cu(SCOth)(2)] (2) (where th = thiophene) were synthesized and characterized structurally by X-ray crystallography. Electronic absorption and emission spectral properties of the two compounds have been studied. Cu(II) complexes, [(TMEDA)Cu(SCOth)(2)] (3b) and [(Phen)Cu(SCOth)(2)] (4a) (where TMEDA = tetramethylethylenediamine; Phen = 1,10-phenanthroline) were prepared and characterized by spectroscopic measurements. 3b and 4a underwent desulfurization under ambient conditions readily yielding the corresponding carboxylate complexes [(TMEDA)Cu(O(2)Cth)(2)] (3a) and [(Phen)Cu(O(2)Cth)(2)·H(2)O] (4b). 3a and 4b have been characterized crystallographically.     

Palladium@gold bimetallic nanostructures as peroxidase mimic for development of sensitive fluoroimmunoassay

In this paper, gold nanoparticles coated with palladium dots (Pd@Au) bimetallic nanostructures have been reported to have a peroxidase like activity which is not found in their monometallic counterparts. Based on this finding, we have developed an immunoassay in which antibody-modified Pd@Au nanostructure catalyzes the dimerization of a fluorogenic substrate for peroxidase, 3-(4-dihydroxy phenyl) propionic acid (HPPA), to generate high fluorescence signal. Specific antibodies against bensulfuron-methyl were generated by using a well characterized bensulfuron–protein conjugate as an immunogen, and the assay was performed in a competitive immunoassay format where Pd@Au nanostructure was bound to secondary antibody to show the peroxidase like activity. The developed immunoassay exhibited an excellent sensitivity showing a dynamic response range from 0.001 to 100 ng mL⁻¹ for herbicide bensulfuron-methyl with a detection limit of 0.01 ng mL⁻¹ (n = 3). The newly synthesized bimetallic nanostructure shows the advantages of low cost, easy synthesis and tunable catalytic activity, making it a promising substitution of enzyme peroxidase in different applications.     

Five coordinate complexes of N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamide with copper Crystal and molecular structures of dichloro(N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamido)copper(II) and chloro(perchlorato)(N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamido)copper(II)

The title compound N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamide (DEAP) forms a 1:1 complex with anhydrous CuCl₂, [Cu(DEAP)Cl₂], (1) which was crystallized from EtOH solution in the monoclinic space group P2_{1/ n} with cell constant, a = 10.024(1); b = 13.122(1); c = 14.404(1) Å β = 101.31(1)° V = 1857.8(3) ų and Z = 4. The chloro-perchlorato complex, [Cu(DEAP)Cl(ClO₄)], (2) obtained in near quantitative yield by reacting (1) with an excess of NaClO₄ in EtOH, crystallized in the monoclinic space group P2_{1/ n} with cell constants, a = 7.965(1); b = 25.827(2); c = 10.046(1) Å β = 98.81(1)° V = 2042.2(4) ų and Z = 4. Both (1) and (2) contain 5-coordinated copper linked to DEAP through O～N～O donor set of atoms with covalently bonded chlorine atoms in (1) and chlorine and perchlorate groups in (2). The coordination geometry is intermediate between square pyramidal and trigonal bipyramidal, and is probably best described as a trigonally distorted rectangular pyramid.     

Diffusion and phase transitions in barium monolayers on the (011) plane of tungsten

The diffusion parameters of barium on W(011) are shown to correlate with phase transitions in the adlayer. A suprisingly strong difference is found both in absolute values and in the coverage dependence of the diffusion parameters for barium on the (011) plane of W and Mo. A considerably lower mobility of barium on molybdenum is attributed to a larger contribution of covalent bonding on this substrate. It is concluded that the electron structure, together with the atomic structure of a surface, plays an important role in surface diffusion.