Effects of liposomal phophatidylserine on phagocytic uptake of liposomes by macrophage-like HL-60RG cells

The purpose of this work is to know the effect of surface properties of liposomes on their phagocytic uptake by macrophages. For this, liposomes were prepared by the Bangham technique from the mixture of phosphatidylcholine (PC) and cholesterol (Chol) incorporated either with phosphatidylserine (PS), phosphatidylethanolamine (PE) or phosphatidic acid (PA). The liposomes thus prepared had diameters in the range between 150 and 260 nm. Electric surface properties of the liposomes and the macrophages differentiated from HL-60RG cells were determined by measuring their electrophoretic mobilities. The phagocytic uptake of liposomes with different contents of PS, PE and PA by macrophage-like HL-60RG cells was investigated by measuring oxygen consumption associated with phagocytic uptake. The phagocytic activity was found to be the highest with the PC–Chol liposomes containing 7 mol% PS, but no significant effects were observed with PA- and PE-containing PC–Chol liposomes. As the uptake was independent of the electric surface property of liposomes, PS was concluded to be specifically important for phagocytic activity of macrophages.     

Modified Henry function for the electrophoretic mobility of a charged spherical colloidal particle covered with an ion-penetrable uncharged polymer layer

An approximate expression is derived for the electrophoretic mobility of a spherical charged colloidal particle carrying low zeta potential covered with an ion-penetrable uncharged polymer layer in an electrolyte solution. This expression, which becomes Henry's mobility formula in the absence of the polymer layer, is a modification of Henry's mobility formula by taking into account the presence of the uncharged polymer layer.     

Electrospray multistage mass spectrometry in the negative ion mode for the unambiguous molecular and structural characterization of acidic hydrolysates from 4‐O‐methylglucuronoxylan generated by endoxylanases

A rapid analytical methodology is proposed to answer the two questions about the molecular and structural features of the acidic xylo‐oligosaccharides (XOSs) formed upon the enzymatic hydrolysis of 4‐O‐methylglucuronoxylan. The shortest acidic XOSs carrying a methylglucuronic acid moiety and the possible distribution of larger products (molecular feature) are instantly found by electrospray ionization mass spectrometry (ESI‐MS) in the negative ion mode, which filters the unwanted neutral XOS. The acidic moiety is then unambiguously localized along the xylose backbone (structural feature) by ESI‐MSⁿ in the negative ion mode via the selection/activation/dissociation of the product ions formed upon the one‐way and stepwise glycosidic bond cleavage at the reducing end. Using the shortest acidic XOS with a known shape generated by glycoside hydrolase family (GH) 10 and GH11 xylanases as a proof of principle, pairs of diagnostic ions are proposed to instantly interpret the MSⁿ fingerprints and localize the acidic moiety along the xylose chain of the activated ion. The original structure of the acidic XOS is then reconstructed by adding as many xylose units at the reducing end as MSⁿ steps. Relying on pairs of ions, the methodology is robust enough to highlight the presence of isomeric products. Mass spectra reported in the present article will be conveniently used as reference data for the forthcoming analysis of acidic XOS generated by new classes of enzymes using this multistage mass spectrometry methodology.     

Non-classical control of solid-state aggregation-induced enhanced circularly polarized luminescence in chiral perylene diimides

Organic fluorescent molecules are gaining importance because of their potential applications in many devices. Optically active N,N′-bis((1R)-1-naphthylethyl)perylene-3,4,9,10-tetracarboxylic diimide [(R,R)-1-BNP] and N,N′-bis((1R)-2-naphthylethyl)perylene-3,4,9,10-tetracarboxylic diimide [(R,R)-2-BNP] and their antipode, [(S,S)-1-BNP and (S,S)-2-BNP], emit aggregation-induced enhanced (AIEnh) circularly polarized luminescence (CPL) on both a solid organic polymer film (poly(methyl methacrylate)) and solid inorganic KBr pellet. An opposite chirality is essential for generating CPL of inverted sign. However, a pair of enantiomeric organic molecules may not always be easy to prepare. Interestingly, the chiral perylene fluorophores synthesized in this study can emit both positive and negative AIEnh-CPL in the solid state, depending on their position on the naphthylene groups. In addition, no CPL was observed in these compounds from their dilute solutions.     

Furopyridines. XII . Reaction of 3-bromo, 2-phenylthio and 2-phenylthio-3-bromo derivatives of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine with several alkyllithiums

This paper describes reactions of 3-bromo- 1a-d , 2-phenylthio- 5a-d and 2-phenylthio-3-bromofuropyridines 6a-d with n-butyl-, t-butyl- and methyllithium and lithioacetonitrile. Lithiation of compounds 1a-d with n-butyl- or methyllithium gave the parent furopyridines 2a-d and o-ethynylpyridinols 3a-d. Reaction of compounds 5a-d with methyllithium afforded o-(phenylthioethynyl)pyridinols 7a-d , which were also yielded by reaction of compounds 6a-d with t-butyl- or methyllithium. The phenylthio group in compounds 7a-d were substituted with t-butyl group by the reaction with excess t-butyllithium. In contrast, 2-phenylthio group in compounds 5a-d and 6a-d was substituted with cyanomethyl group by reaction with lithioacetonitrile to give compounds 11a-d and 10b, c respectively.     

Magnetic Circular Dichroism and Electronic Spectra of Tropothione

The magnetic circular dichroism (MCD) and electronic absorption spectra of tropothione have been measured. The circular-dichroism (CD) spectrum of the β-cyclodextrin complex with tropothione is also reported. The absorption bands of tropothione are assigned.     

Palladium-catalyzed oxidative homocoupling reaction of terminal acetylenes using trans-bidentatable 1-(2-pyridylethynyl)-2-(2-thienylethynyl)benzene

Palladium-catalyzed oxidative homocoupling of terminal acetylenes, in air, occurred in the presence of 1-(2-pyridylethynyl)-2-(2-thienylethynyl)benzene as ligand, affording the corresponding conjugated diynes.     

A New Family of Trinuclear Nickel(II) Complexes as Single‐Molecule Magnets

Three new trinuclear nickel (II) complexes with the general composition [Ni₃L₃(OH)(X)](ClO₄) have been prepared in which X=Cl^? ( 1 ), OCN^? ( 2 ), or N₃^? ( 3 ) and HL is the tridentate N,N,O donor Schiff base ligand 2‐[(3‐dimethylaminopropylimino)methyl]phenol. Single‐crystal structural analyses revealed that all three complexes have a similar Ni₃ core motif with three different types of bridging, namely phenoxido (μ₂ and μ₃), hydroxido (μ₃), and μ₂‐Cl ( 1 ), μ_1,1‐NCO ( 2 ), or μ_1,1‐N₃ ( 3 ). The nickel(II) ions adopt a compressed octahedron geometry. Single‐crystal magnetization measurements on complex 1 revealed that the pseudo‐three‐fold axis of Ni₃ corresponds to a magnetic easy axis, being consistent with the magnetic anisotropy expected from the coordination structure of each nickel ion. Temperature‐dependent magnetic measurements indicated ferromagnetic coupling leading to an S=3 ground state with 2J/k=17, 17, and 28 K for 1 , 2 , and 3 , respectively, with the nickel atoms in an approximate equilateral triangle. The high‐frequency EPR spectra in combination with spin Hamiltonian simulations that include zero‐field splitting parameters D_Ni/k=?5, ?4, and ?4 K for 1 , 2 , and 3 , respectively, reproduced the EPR spectra well after a anisotropic exchange term was introduced. Anisotropic exchange was identified as D_i,j/k=?0.9, ?0.8, and ?0.8 K for 1 , 2 , and 3 , respectively, whereas no evidence of single‐ion rhombic anisotropy was observed spectroscopically. Slow relaxation of the magnetization at low temperatures is evident from the frequency‐dependence of the out‐of‐phase ac susceptibilities. Pulsed‐field magnetization recorded at 0.5 K shows clear steps in the hysteresis loop at 0.5–1 T, which has been assigned to quantum tunneling, and is characteristic of single‐molecule magnets.