Synthesis and characterization of chemically anchored adenosine with PHEMA grafted gold nanoparticles

The synthesis of chemically anchored adenosine with biocompatible poly(2-hydroxylethyl methacrylate) grafted gold nanoparticles (Ado-i-PHEMA-g-AuNPs) was realized by employing a simple strategy. Disulfide-containing poly(2-hydroxylethyl methacrylate) (DT-PHEMA) was initially synthesized by atom transfer radical polymerization (ATRP). The formation of DT-PHEMA was confirmed by ¹H-NMR and FT-IR. The molecular weight and molecular weight distribution were found to be 9.6 kg/mol and 1.40 from GPC analysis. DT-PHEMA was subsequently used for the synthesis of PHEMA-g-AuNPs by a grafting to protocol. The grafting of DT-PHEMA on the surface of AuNPs was confirmed by FT-IR, TGA, XPS, and EDX analyses. The particle size of the PHEMA-g-AuNPs was found to be ca. 5.0 nm from HR-TEM analysis. Boronic acid was used for functionalization of PHEMA-g-AuNPs, which was then subjected for covalent immobilization with adenosine via strong interaction between free hydroxyl groups of adenosine and boronic acid. Characterization and properties of the Ado-i-PHEMA-g-AuNPs were investigated by taking advantage from FT-IR, XPS, EDX, and UV-visible spectroscopy. The Ado-i-PHEMA-g-AuNPs nanocomposite exhibits a surface plasmon resonance peak at 586 nm which is red shifted from AuNPs (521 nm), indicating significant changes of surface property upon PHEMA-adenosine immobilization onto the surface of AuNPs.     

Tracing the geographical origin of beefs being circulated in Korean markets based on stable isotopes

We have examined the carbon, nitrogen and oxygen isotopic compositions of American, Mexican, Australian, New Zealand and Korean beefs, which are currently being circulated in Korean markets, to check whether stable isotope ratios can identify their country of origin. Each beef exhibited statistically distinct isotopic compositions, especially in oxygen and carbon, because of the different isotopic compositions of their water and cattle feeds. Nevertheless, their isotopic compositions still showed some overlap, especially among USA, Australian, and Korean beefs, which sometimes resulted in significant misidentification when a single isotope was considered. However, the discrimination was generally successful when both the carbon and the oxygen isotopes were used. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimal poroelastic layer sequencing for sound transmission loss maximization by topology optimization method

Optimal layer sequencing of a multilayered acoustical foam is solved to maximize its sound transmission loss. A foam consisting of air and poroelastic layers can be optimized when a limited amount of a poroelastic material is allowed. By formulating the sound transmission loss maximization problem as a one-dimensional topology optimization problem, optimal layer sequencing and thickness were systematically found for several single and ranges of frequencies. For optimization, the transmission losses of air and poroelastic layers were calculated by the transfer matrix derived from Biot's theory. By interpolating five intrinsic parameters among several poroelastic material parameters, distinct air-poroelastic layer distributions were obtained; no filtering or postprocessing was necessary. The optimized foam layouts by the proposed method were shown to differ depending on the frequency bands of interest.     

Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis

The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34⁺ HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34⁺ cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34⁺ cells, but not CD34⁻ cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80⁺ macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.     

Biflavones and Furanone Glucosides from Zabelia tyaihyonii

Two new biflavones, (aR)‐3′‐methoxycupressuflavone ( 1 ) and (aR)‐3′,3′′′‐dimethoxycupressuflavone ( 2 ), and two new furanone glucosides, zabeliosides A and B ( 3 and 4 , resp.), along with two known biflavones, cupressuflavone ( 5 ) and amentoflavone ( 6 ), were isolated from the leaves of Zabelia tyaihyonii. The structures of the new compounds were elucidated by 1D‐ and 2D‐NMR, HR‐ESI‐MS, and circular dichroism.     

Two New C‐seco Limonoids from the Fruit of Melia azedarach

A phytochemical investigation of the fruits of Melia azedarach led to the isolation of two new C‐seco‐nimbolinin‐type limonoids, 3α‐acetoxy‐1α,7α‐dihydroxy‐12α‐methoxynimbolinin ( 1 ) and 3α‐acetoxy‐1α,12α‐dihydroxy‐7α‐(2‐methylprop‐2‐enoyl)nimbolinin ( 2 ), together with eleven known compounds, 3 – 13 . Their structures were elucidated on the basis of extensive spectroscopic analysis, including ¹H‐ and ¹³C‐NMR, HMQC, HMBC, NOESY, and HR‐FAB‐MS.     

TiO2–SiO2 in PEG: A Highly Efficient Green Catalytic System for One‐Pot Synthesis of Benzo[a]xanthen‐11‐ones

Polyethylene glycol was found to be an inexpensive non‐toxic and effective medium for the one‐pot synthesis of benzo[a]xanthen‐11‐ones in the presence of TiO₂–SiO₂ as the catalyst in good to excellent yield. The salient features of this protocol are the simplicity of the procedure, the ready accessibility of the catalyst, its cost effectiveness, and reusable catalyst in relatively short reaction times.     

BF3·SiO2-catalyzed one-pot synthesis of α-aminophosphonates in ionic liquid and neat conditions

α-Aminophosphonates were synthesized in a simple and efficient method from the three-component condensation reaction of 5-amino 2,2-difluoro-1,3-benzodioxole, aromatic aldehydes, and diethyl phosphite by silica-supported boron trifluoride (BF₃·SiO₂) in ionic liquid ([bmim][HCl]) under solvent-free conditions at room temperature in good to excellent yields and short reaction times. The catalyst can be recovered and reused for several times without any significant loss of activity. It was observed that a homogeneous reaction medium proved beneficial for the yield of the reaction.     

Gold nanoparticle-based homogeneous fluorescent aptasensor for multiplex detection

We developed a homogeneous fluorescence assay for multiplex detection based on the target induced conformational change of DNA aptamers. DNA aptamers were immobilized on quantum dots (QDs), and QDs conjugated ssDNA was adsorbed on the surface of gold nanoparticles (AuNPs) by electrostatic interaction between uncoiled ssDNA and the AuNPs. Subsequently the fluorescence of QDs was effectively quenched by the AuNPs due to fluorescence resonance energy transfer (FRET) of QDs to AuNPs. In the presence of targets, the QDs conjugated aptamers were detached from AuNPs by target induced conformational change of aptamers, consequently the fluorescence of the QDs was recovered proportional to the target concentration. In this study, three different QD/aptamer conjugates were used for multiplex detection of mercury ions, adenosine and potassium ions. In a control experiment, all of the three targets were simultaneously detected with high selectivity.