Chemo-enzymatic synthesis of (−)-epipentenomycin I

A chemo-enzymatic synthesis of (−)-epipentenomycin I is reported using a lipase-catalysed kinetic resolution of the racemic pentacyclic alcohol 8. Flash vacuum pyroloysis of (−)-8 so obtained gave (−)-(4R)-4-hydroxy-5-methylene-2-cyclopentenone. Epoxidation of this compound with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide gave (−)-epipentenomycin I.     

Oriented conjugation of antibodies against the epithelial cell adhesion molecule on fluorescently doped silica nanoparticles for flow-cytometric determination and <Emphasis Type="Italic">in vivo</Emphasis> imaging of EpCAM,a biomarker for colorectal cancer

The authors report on the conjugation of monoclonal antibodies against the biomarker epithelial cell adhesion molecule (EpCAM) to silica nanoparticles doped with the dye Cy5 (Cy5-SiNPs). Conjugation was performed on the Cy5-SiNPs that were previously coated with a layer of protein G which serves as a linker controlling the orientation of the antibody. The conjugation method takes advantage of site specific interactions between the protein G and constant domains (Fc) of the antibody. The method warrants the antibody binding sites (Fab) to be faced outwards such that the conjugates maintain their affinity for binding the analyte (EpCAM). In vitro analysis by confocal fluorescence imaging and flow cytometry using analytical wavelengths comparable with the excitation and emission wavelength of Cy5-SiNPs at 643 and 662 nm, respectively. The result demonstrated the oriented conjugate to specifically bind to target cells (HT-29) with a sensitivity that is 12 times higher than that of conjugates prepared by conventional EDC coupling. In vivo fluorescence imaging of mice bearing the HT-29 tumor highlighted time-dependent accumulation of the oriented conjugates at the tumor site. As indicated by biodistribution studies hepatic excretion of the oriented probes occurs, however tumor fluorescence still remains for up to 14 days post injection. This research demonstrates that the oriented conjugates derived herein can improve target cell detection sensitivity and can be successfully applied in tumor imaging, which should drive further development of new classes of effective fluorescence contrast agents for cancer diagnostics.

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Graphical abstract Cy5 dye-doped silica nanoparticles were conjugated to antibodies specific for the epithelial cell adhesion molecule. The nanoparticles were previously coated with protein G to control the orientation of the antibody. This warrants enhanced sensitivity for in vitro analysis and also enables in vivo imaging.

     

Dual-layered and double-targeted nanogold based lateral flow immunoassay for influenza virus

Microchimica Acta - We report on a highly sensitive lateral flow immunoassay (LFIA) for influenza A which serves as a model antigen. Gold nanoparticles conjugated to monoclonal antibodies specific...     

Synthesis and Biological Activity Evaluation of Coumarin-3-Carboxamide Derivatives

A series of novel coumarin-3-carboxamide derivatives were designed and synthesized to evaluate their biological activities. The compounds showed little to no activity against gram-positive and gram-negative bacteria but specifically showed potential to inhibit the growth of cancer cells. In particular, among the tested compounds, 4-fluoro and 2,5-difluoro benzamide derivatives (14b and 14e, respectively) were found to be the most potent derivatives against HepG2 cancer cell lines (IC₅₀ = 2.62–4.85 μM) and HeLa cancer cell lines (IC₅₀ = 0.39–0.75 μM). The activities of these two compounds were comparable to that of the positive control doxorubicin; especially, 4-flurobenzamide derivative (14b) exhibited low cytotoxic activity against LLC-MK2 normal cell lines, with IC₅₀ more than 100 μM. The molecular docking study of the synthesized compounds revealed the binding to the active site of the CK2 enzyme, indicating that the presence of the benzamide functionality is an important feature for anticancer activity.     

Rapid and sensitive lateral flow immunoassay for influenza antigen using fluorescently-doped silica nanoparticles

We report on a lateral flow immunoassay (LFIA) for influenza A antigen using fluorescently-doped silica nanoparticles as reporters. The method is taking advantage of the high brightness and photostability of silica nanoparticles (doped with the dye Cy5) and the simplicity and rapidity of LFIA. The nucleoprotein of influenza A virion (one of its most abundant structural proteins) was used as a model to demonstrate a performance of the LFIA. Under optimized conditions and by using a portable strip reader, the fluorescence-based LFIA is capable of detecting a recombinant nucleoprotein as low as 250 ng?·?mL^-1 using a sample volume of 100 μL, within 30 min, and without interference by other proteins. The successful detection of the nucleoprotein in infected allantoic fluid demonstrated the functionality of the method. By comparison with a commercial influenza A test based on gold nanoparticles as reporters, the system provides an 8-fold better sensitivity.

Constituents of the essential oil from aerial parts of Chromolaena odorata from Thailand

The chemical composition of the essential oil from the aerial parts of Chromolaena odorata, collected from Phitsanulok, Thailand was analyzed by means of GC-(FID) and GC-MS. Twenty-two constituents were identified. The major components were pregeijerene (17.6%), germacrene D (11.1%), alpha-pinene (8.4%), beta-caryophyllene (7.3%), vestitenone (6.5%), beta-pinene (5.6%), delta-cadinene (4.9%), geijerene (3.1%), bulnesol (2.9%), and trans-ocimene (2.2%).     

Laser desorption/ionization mass spectrometry analysis of monolayer-protected gold nanoparticles

Monolayer-protected gold nanoparticles (AuNPs) feature unique surface properties that enable numerous applications. Thus, there is a need for simple, rapid, and accurate methods to confirm the surface structures of these materials. Here, we describe how laser desorption/ionization mass spectrometry (LDI-MS) can be used to characterize AuNPs with neutral, positively, and negatively charged surface functional groups. LDI readily desorbs and ionizes the gold-bound ligands to produce both free thiols and disulfide ions in pure and complex samples. We also find that LDI-MS can provide a semi-quantitative measure of the ligand composition of mixed-monolayer AuNPs by monitoring mixed disulfide ions that are formed. Overall, the LDI-MS approach requires very little sample, provides an accurate measure of the surface ligands, and can be used to monitor AuNPs in complex mixtures.