Bioorthogonal Labeling,Bioimaging, and Photocytotoxicity Studies of Phosphorescent Ruthenium(II) Polypyridine Dibenzocyclooctyne Complexes

The synthesis, characterization, photophysics, lipophilicity, and cellular properties of new phosphorescent ruthenium(II) polypyridine complexes functionalized with a dibenzocyclooctyne (DIBO) or amine moiety [Ru(N^N)₂(L)](PF₆)₂ are reported (L=4‐(13‐N‐(3,4:7,8‐dibenzocyclooctyne‐5‐oxycarbonyl) amino‐4,7,10‐trioxa‐tridecanyl‐aminocarbonyl‐oxy‐methyl)‐4′‐methyl‐2,2′‐bipyridine bpy‐DIBO, N^N=2,2′‐bipyridine bpy ( 1 a ), 1,10‐phenanthroline phen ( 2 a ); L=4‐(13‐amino‐4,7,10‐trioxa‐tridecanylaminocarbonyl‐oxy‐methyl)‐4′‐methyl‐2,2′‐bipyridine bpy‐NH₂, N^N=bpy ( 1 b ), phen ( 2 b )). The strain‐promoted alkyne–azide cycloaddition (SPAAC) reaction of the DIBO complexes 1 a and 2 a with benzyl azide were studied. Also, the DIBO complexes 1 a and 2 a can selectively label N‐azidoglycans located on the surface of CHO‐K1 and A549 cells that were pretreated with 1,3,4,6‐tetra‐O‐acetyl‐N‐azidoacetyl‐D ‐mannosamine (Ac₄ManNAz). Additionally, the intracellular trafficking and localization of these biomolecules were monitored using laser‐scanning confocal microscopy. Interestingly, the biolabeling and cellular uptake efficiency of the DIBO complexes 1 a and 2 a were cell‐line dependent, as revealed by flow cytometry and ICP‐MS. Furthermore, the complexes showed good biocompatibility toward the Ac₄ManNAz‐pretreated cells in the dark, but exhibited photoinduced cytotoxicity due to the generation of singlet oxygen.     

A novel blue magnesium strontium aluminate-based phosphor for PDP application

A novel blue light-emitting phosphor, Eu²⁺-doped magnesium strontium aluminate (MgSrAl₁₀O₁₇:Eu²⁺), for plasma display panel (PDP) application was developed. X-ray diffraction (XRD) patterns disclosed that the phosphor annealed at 1500 °C for 5 h was a pure MgSrAl₁₀O₁₇ phase. Field emission scanning electron microscopy (FE-SEM) images showed the particle size of the phosphor was less than 3 μm. The phosphor shows strong and broad blue emission under vacuum ultraviolet (VUV) light excitation. After baking at 400-600 °C and irradiation with VUV light for 300 h, the phosphor still keep excellent VUV luminescence properties exhibiting good stability against high temperature baking and VUV irradiation. The decay time was short as 1.09 μs and the quantum yield was high to 0.77±0.02. All the characteristics indicated that MgSrAl₁₀O₁₇:Eu²⁺ would be a promising blue phosphor for PDP application.     

Geometric metasurface fork gratings for vortex‐beam generation and manipulation

In recent years, optical vortex beams possessing orbital angular momentum have received much attention due to their potential for high‐capacity optical communications. This capability arises from the unbounded topological charges of orbital angular momentum (OAM) that provide infinite freedoms for encoding information. The two most common approaches for generating vortex beams are through fork diffraction gratings and spiral phase plates. While realization of conventional spiral phase plate requires complicated 3D fabrication, the emerging field of metasurfaces has provided a planar and facile solution for generating vortex beams of arbitrary orbit angular momentum. Among various types of metasurfaces, the geometric phase metasurface has shown great potential for robust control of light‐ and spin‐controlled wave propagation. Here, we realize a novel type of geometric metasurface fork grating that seamlessly combine the functionality of a metasurface phase plate for vortex‐beam generation, and that of a linear phase gradient metasurface for controlling the wave‐propagation direction. The metasurface fork grating is therefore capable of simultaneously controlling both the spin and the orbital angular momentum of light.

     

Fast and Sensitive HPLC-ESI-MS/MS Method for Etoricoxib Quantification in Human Plasma and Application to Bioequivalence Study

Etoricoxib is a non-steroidal anti-inflammatory drug (NSAID) used to treat pain and inflammation. The objective of the current study was to develop a sensitive, fast and high-throughput HPLC-ESI-MS/MS method to measure etoricoxib levels in human plasma using a one-step methanol protein precipitation technique. A tandem mass spectrometer equipped with an electrospray ionization (ESI) source operated in a positive mode and multiple reaction monitoring (MRM) were used for data collection. The quantitative MRM transition ions were m/z 359.15 > 279.10 and m/z 363.10 > 282.10 for etoricoxib and IS. The linear range was from 10.00 to 4000.39 ng/mL and the validation parameters were within the acceptance limits of the European Medicine Agency (EMA) and Food and Drug Analysis (FDA) guidelines. The present method was sensitive (10.00 ng/mL with S/N > 40), simple, selective (K prime > 2), and fast (short run time of 2 min), with negligible matrix effect and consistent recovery, suitable for high throughput analysis. The method was used to quantitate etoricoxib plasma concentrations in a bioequivalence study of two 120 mg etoricoxib formulations. Incurred sample reanalysis results further supported that the method was robust and reproducible.     

Development and validation of a gas chromatography/mass spectrometry method for the metabolic profiling of human colon tissue

In this study, a gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the metabolic profiling of human colon tissue. Each colon tissue sample (20 mg) was ultra‐sonicated with 1 mL of a mixture of chloroform/methanol/water in the ratio of 20:50:20 (v/v/v), followed by centrifugation, collection of supernatant, drying, removal of moisture using anhydrous toluene and finally derivatization using N‐methyl‐N‐trifluoroacetamide (MSTFA) with 1% trimethylchlorosilane (TMCS). A volume of 1 µL of the derivatized mixture was injected into the GC/MS system. A total of 53 endogenous metabolites were separated and identified in the GC/MS chromatogram, all of which were selected to evaluate the sample stability and precision of the method. Of the identified endogenous metabolites 19 belonging to diverse chemical classes and covering a wide range of the GC retention times (Rt) were selected to investigate the quantitative linearity of the method. The developed GC/MS method demonstrated good reproducibility with intra‐ and inter‐day precision within relative standard deviation (RSD) of ±15%. The metabolic profiles of the intact tissue were determined to be stable (100 ± 15%) for up to 90 days at ?80°C. Satisfactory results were also obtained in the case of other stability‐indicating studies such as freeze/thaw cycle stability, bench‐top stability and autosampler stability. The developed method showed a good linear response for each of the 19 analytes tested (r² > 0.99). Our GC/MS metabolic profiling method was successfully applied to discriminate biopsied colorectal cancer (CRC) tissue from their matched normal tissue obtained from six CRC patients using orthogonal partial least‐squares discriminant analysis [two latent variables, R²Y = 0.977 and Q² (cumulative) = 0.877]. Copyright © 2009 John Wiley & Sons, Ltd.     

Optical properties of a novel yellow fluorescent dopant for use in organic LEDs

In this paper, the optical properties of a novel organic, 2,8-di(t-butyl)-5,11-di[4(t-butyl) phenyl]-6,12-diphenylnaphthacene (tetra(t-butyl)rubrene) have been investigated. Our results show that there are two peaks in the photoluminescence (PL) spectra of tetra(t-butyl)rubrene (TBRb) which are also confirmed in the electroluminescence (EL) spectra. Photo-quenching of the PL intensity is observed when the irradiation time increases. It is shown that oxidation is the dominant reason for photo-quenching. The absolute refractive index and absorption coefficient have also been determined and the results correlate well with the PL results. The results show that TBRb can be a good dopant to achieve the Förster energy transfer and to assist light emission. The optical properties of TBRb are similar to those of rubrene; however, the PL of TBRb is much stronger than that of rubrene. Finally, although crystalline organics have been commonly reported by heating the sample, we report crystallization of TBRb at low temperature <230 K when the TBRb film is in an amorphous form before cooling. PACS 78.47.+p; 78.55.-m; 81.05.Lg; 85.60.-q     

Synthesis of anti-bacterial peptidomimetics derived from N-acylisatins

An efficient synthetic strategy to mono- and bis-glyoxylamide derivatives via the reaction of N-acylisatins with a range of amino acids has been developed. Using this strategy, a series of new peptidomimetics have been synthesized.