“Pointsource” Delivery of a Photosensitizer Drug and Singlet Oxygen: Eradication of Glioma Cells In Vitro

We describe a pointsource sensitizer‐tipped microoptic device for the eradication of glioma U87 cells. The device has a mesoporous fluorinated silica tip which emits singlet oxygen molecules and small quantities of pheophorbide sensitizer for additional production of singlet oxygen in the immediate vicinity. The results show that the device surges in sensitizer release and photokilling with higher rates about midway through the reaction. This was attributed to a self‐amplified autocatalytic reaction where released sensitizer in the extracellular matrix provides positive feedback to assist in the release of additional sensitizer. The photokilling of the glioma cells was analyzed by global toxicity and live/dead assays, where a killing radius around the tip with ~0.3 mm precision was achieved. The implication of these results for a new PDT tool of hard‐to‐resect tumors, e.g. in the brain, is discussed.     

Processing and properties of melt spun polylactide–multiwall carbon nanotube fiber composites

This article reports on the fabrication of oriented composite fibers between polylactide (PLA) and multiwall carbon nanotube (MWNT). The fibers were fabricated using a custom‐built melt fiber‐drawing setup. The influence of processing parameters on the final fiber diameter and on the orientation were characterized and optimized. Composite fibers were fabricated at various MWNT contents. Addition of low amounts of MWNT (0.25–1 wt %) to PLA did not have a significant effect on the diameters of the fibers. Observations of the composite morphology under STEM indicated preferential orientation of the MWNTs along the draw direction of the fibers. Increasing amounts of MWNTs was found to increase crystallization kinetics and content. The crystalline content had a direct and profound implication on the mechanical properties with 0.5‐wt % MWNT fibers having the highest crystalline content and also the highest Young's modulus. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 477–484     

On the use of hydrogen peroxide as a masking agent for the determination of yttrium in uranium oxide-yttrium oxide mixture

Use of hydrogen peroxide as a masking agent for uranium during the EDTA titration of yttrium in an yttrium-uranium mixture containing large amounts of uranium has been investigated. High acetate ion concentration was necessary to keep the peroxy complex of uranium in solution during the titration. It has been observed that upto 500 mg of uranium could be tolerated in the determination of yttrium with 0.5 ml of 30% hydrogen peroxide in {lM acetate medium. The precision and accuracy of the method based on 16 determinations of yttrium at 6–16 mg level in presence of 300 mg uranium has been found to be ±0.2%.     

Polymeric alkenoxy amino acid surfactants: III. Chiral separations of binaphthyl derivatives

Micellar electrokinetic chromatography (MEKC) was investigated for the enantiomeric separations of three binaphthyl derivatives ((+/-)-1,1'-bi-(2-naphthol) (BOH), (+/-)-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BNP), and (+/-)-1,1'-binaphthyl-2,2'-diamine (BNA)) using two recently synthesized chiral polymeric surfactants (polysodium N-undecenoxy carbonyl-L-leucinate (poly-L-SUCL) and polysodium N-undecenoxy carbonyl-L-isoleucinate (poly-L-SUCIL)) in our laboratory. Enantiomeric separation (resolution and selectivity) of the binaphthyl derivatives was influenced by polymerization concentration of the monomeric surfactant, pH, type and concentration of the background electrolyte (BGE) as well as concentration of the polymeric surfactant. Two BGEs (dibasic phosphate and Tris-borate) were compared for this study. The use of dibasic phosphate as BGE in poly-L-SUCL provides baseline resolution of (+/-) BOH and (+/-) BNP, however, no resolution and selectivity at all was observed for (+/-) BNA. A similar approach was adopted with Tris-borate-poly-L-SUCL system at fixed pH 10.1, which resulted in baseline resolution of all three binaphthyl derivatives. Although R(s) of binaphthyl derivatives was always higher and electroosmotic flow (EOF) was always lower using Tris-borate than with dibasic phosphate, the selectivity values for the two buffer systems did not differ significantly. In addition, it was found that poly-L-SUCL provided better enantiomeric resolution and selectivity for (+/-) BOH and (+/-) BNA, while poly-L-SUCIL provided enhanced enantiomeric resolution but similar enantioselectivity for (+/-) BNP. This indicates that the depth of analyte penetration into the palisade layer and the micellar core are responsible for chiral recognition of hydrophobic analyte (e.g., (+/-) BOH, and (+/-) BNA) whereas for moderately hydrophobic analyte (e.g., (+/-) BNP) interaction with the polar head group seems to dictate chiral recognition. Simultaneous enantioresolution of all three binaphthyl derivatives was possible in a single electrophoretic run using either poly-L-SUCL or poly-L-SUCIL. Further comparison of the two polymeric surfactants showed that poly-L-SUCL provided slightly longer analysis time than poly-L-SUCIL but the use of the former polymeric surfactant should be preferred due to its ability to provide complete baseline resolution and higher selectivity of all the three atropisomers with a wider chiral window.     

Modified pyrohydrolysis apparatus for the separation of fluorine and chlorine trace impurities from nuclear fuel samples for quality control analysis

A quartz pyrohydrolysis apparatus designed for the safe handling of pyrophoric carbide nuclear fuel samples while separating C1 and F trace impurities for quality control analysis is described. It has several advantages over the commonly used pyrohydrolysis apparatus. Performance of the apparatus during routine analysis of a large number of nuclear fuel samples has been found to be quite satisfactory.     

A new series of luminescent phosphine stabilised platinum ethynyl complexes

A series of cis-platinum ethynyl complexes with the general formula cis-[Pt(dppe)(C[triple bond]CR)2](dppe = 1,2-bis(diphenylphosphino)ethane; R = C6H4-p-NO2 1, C6H4-p-CH3 2, C6H4-p-C[triple bond]CH 3 and C6H4-p-C6H4-p-C[triple bond]CH 4) have been prepared by the coupling reaction of cis-[Pt(dppe)Cl2] with two equivalents of the appropriate alkyne. The new complexes have been fully characterized by spectroscopic techniques, and the cis square planar arrangement at the platinum centre has been confirmed by single-crystal X-ray diffraction studies of complexes 1, 2 and 4. The absorption spectra of the complexes 1-4 are dominated by a pi-->pi* band that contains some platinum (n + 1) p orbital character. The position of the band is dependent on the electron donating or withdrawing properties of the ethynyl substituents, R. Complex 1 displays a triplet emission in the green, at room temperature, while complexes 2-4, display singlet emissions in the blue. Again, the difference can be attributed to the nature of the R substituents.     

Synthesis, characterisation and optical spectroscopy of platinum(II) di-ynes and poly-ynes incorporating condensed aromatic spacers in the backbone

A series of protected and terminal dialkynes with extended pi-conjugation through a condensed aromatic linker unit in the backbone, 1,4-bis(trimethylsilylethynyl)naphthalene, 1,4-bis(ethynyl)naphthalene, 9,10-bis(trimethylsilylethynyl)anthracene, 9,10-bis(ethynyl)anthracene, have been synthesized and characterized spectroscopically. The solid-state structures of and have been confirmed by single crystal X-ray diffraction studies. Reaction of two equivalents of the complex trans-[Ph(Et(3)P)(2)PtCl] with an equivalent of the terminal dialkynes 1,4-bis(ethynyl)benzene and, in (i)Pr(2)NH-CH(2)Cl(2), in the presence of CuI, at room temperature, afforded the platinum(II) di-ynes trans-[Ph(Et(3)P)(2)Pt-C[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-Pt(PEt(3))(2)Ph](R = benzene-1,4-diyl; naphthalene-1,4-diyl and anthracene-9,10-diyl ) while reactions between equimolar quantities of trans-[((n)Bu(3)P)(2)PtCl(2)] and under similar conditions readily afforded the platinum(II) poly-ynes trans-[-((n)Bu(3)P)(2)Pt-C[triple bond]C-R-C[triple bond]C-](n)(R = naphthalene-1,4-diyl and anthracene-9,10-diyl ). The Pt(II) diynes and poly-ynes have been characterized by analytical and spectroscopic methods, and the single crystal X-ray structures of and have been determined. These structures confirm the trans-square planar geometry at the platinum centres and the linear nature of the molecules. The di-ynes and poly-ynes are soluble in organic solvents and readily cast into thin films. Optical spectroscopic measurements reveal that the electron-rich naphthalene and anthracene spacers create strong donor-acceptor interactions between the Pt(II) centres and conjugated ligands along the rigid backbone of the organometallic polymers. Thermogravimetry shows that the di-ynes possess a somewhat higher thermal stability than the corresponding poly-ynes. Both the Pt(II) di-ynes and the poly-ynes exhibit increasing thermal stability along the series of spacers from phenylene through naphthalene to anthracene.     

Determination of nitrogen in UO2 by Kjeldahl spectrophotometry

A method for the dissolution of sintered UO₂ samples and the determination of ammonium ions in the solution by spectrophotometry for the chemical quality control of UO₂ fuel for nitrogen is described. The acid mixture used simplifies the problem of recovery of uranium from the waste generated during the analysis of nitrogen. Nitrogen content in ppm in the sintered UO₂ samples is determined within an RSD of 10%.