Small Heteroborane Cluster Systems. 6. Mössbauer Effect Study of Iron Substituted Small Metallaborane Clusters

The M?ssbauer effect spectra for a series of small [Fe(eta(5)-C(5)H(5))(CO)(x)()] substituted metallaborane complexes are reported, where x = 1 or 2. The pentaborane cage in compounds [Fe(eta(5)-C(5)H(5))(CO)(2)B(5)H(7)P(C(6)H(5))(2)] (1), [Fe(eta(5)-C(5)H(5))(CO)(2)B(5)H(8)] (2), and [(Fe(eta(5)-C(5)H(5))(CO)(2))(2)B(5)H(7)] (3) was found to act as a significantly better donor ligand than the ligands in a comparison group of previously reported [Fe(eta(5)-C(5)H(5))(CO)LX] complexes, where L = CO or PPh(3) and X = halide, pseudohalide, or alkyl ligands. These metallaborane complexes were found to most resemble their silyl analogues in M?ssbauer spectral parameters and the electronic distribution around the iron centers. In addition, the M?ssbauer data showed that the [&mgr;-2,3-(P(C(6)H(5))(2)B(5)H(7)](-) ligand was a superior donor to the corresponding unsubstituted [B(5)H(8)](-) ligand. The M?ssbauer spectral results for the metallaborane complexes studied were found to be in general agreement with the anticipated donor and accepting bonding considerations for the cage ligands based upon their infrared and (11)B NMR spectra and X-ray structural features. The M?ssbauer data for the [Fe(eta(5)-C(5)H(5))(CO)B(4)H(6)(P(C(6)H(5))(2))] (4) and [Fe(eta(5)-C(5)H(5))(CO)B(3)H(7)(P(C(6)H(5))(2))] (5) complexes, in comparison with compound 1, showed that as the borane cage becomes progressively smaller, it becomes a poorer donor ligand. A qualitative relationship was found between the observed M?ssbauer isomer shift data and the number of boron cage vertices for the structurally related [Fe(eta(5)-C(5)H(5))(CO)(x)B(y)H(z)P(C(6)H(5))(2)] complexes, where x = 1 or 2, y = 3-5, and z = 6 or 7. The X-ray crystallographic data for compounds 1, 2, 5, and [Fe(eta(5)-C(5)H(5))(CO)B(5)H(8)] (6) were also found to agree with the trends observed in the M?ssbauer spectra which showed that the s-electron density on the iron nucleus increases in the order 5 < 6 < 2 < 1. The X-ray crystal structure of complex 2 is also reported. Crystallographic data for 2: space group P2(1)/c (No. 14, monoclinic), a = 6.084(3) ?, b = 15.045(8) ?, c = 13.449(7) ?, beta = 99.69(5) degrees, V = 1213(1) ?(3), Z = 4 molecules/cell.     

LC–MS/MS method for the simultaneous determination of ethyl gallate and its major metabolite in rat plasma

A simple, rapid and sensitive liquid chromatography–tandem mass spectroscopy (LC–MS/MS) method was developed and validated for the determination of ethyl gallate, a pharmacologically active constituent isolated from Lagerstroemia speciosa (Linn.) Pers. This method was used to examine the pharmacokinetics of ethyl gallate and its major metabolite gallic acid in rat plasma using propyl gallate as an internal standard. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a Zorbax SB‐C₁₈ column (3.5 μm, 2.1 × 50 mm) with an isocratic mobile phase consisted of methanol–acetonitrile–10 mM ammonium acetate (10 : 25 : 65, v/v/v) containing 0.1% formic acid at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple‐reaction monitoring mode using the electrospray ionization technique in negative mode. The lower limits of quantification of gallic acid and ethyl gallate of the method were 0.5 and 1.0 ng/mL. The intra‐day and inter‐day accuracy and precision of the assay were less than 8.0%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of ethyl gallate to rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Study on the surface of fluorosilicone acrylate RGP contact lens treated by low-temperature nitrogen plasma

In order to improve the surface hydrophilicity of fluorosilicone acrylate rigid gas permeable (RGP) contact lens, low temperature nitrogen plasma was used to modify the lens surface. Effects of plasma conditions on the surface structures and properties were investigated. Results indicated that the surface hydrophilicity of RGP contact lens was significantly improved after treatment. X-ray photoelectron spectroscopy (XPS) results showed that the nitrogen element was successfully incorporated into the surface. Furthermore, some new bonds such as NCO, F⁻ and silicate were formed on the lens surface after nitrogen plasma treatment, which could result in the improvement of the surface hydrophilicity. Scanning electronic microscope (SEM) results indicated that nitrogen plasma with moderate power could make the surface smoother in some degree, while plasma with higher power could etch the surface.     

A simple and sensitive HPLC method for the simultaneous determination of eight bioactive components and fingerprint analysis of Schisandra sphenanthera

A simple and sensitive high performance liquid chromatography method with photodiode array detection (HPLC-DAD) was developed for simultaneous determination of eight bioactive constituents (schisandrin, schisandrol B, schisantherin A, schisanhenol, anwulignan, deoxyshisandrin, schisandrin B and schisandrin C) in the ripe fruit of Schisandra sphenanthera and its traditional Chinese herbal preparations Wuzhi-capsule by optimizing the extraction, separation and analytical conditions of HPLC-DAD. The chemical fingerprint of S. sphenanthera was established using raw materials of 15 different origins in China. The chromatographic separations were obtained by an Agilent Eclipse XDB-C18 reserved-phase column (250 mm × 4.6 mm i.d., 5 μm) using gradient elution with water-formic acid (100:0.1, v/v) and acetonitrile, at a flow rate of 1.0 mL min⁻¹, an operating temperature of 35 °C, and a wavelength of 230 nm. The constituents were confirmed by (+) electrospray ionization LC-MS. The new method was validated and was successfully applied to simultaneous determination of components in 13 batches of Wuzhi-capsule. The results indicate that this multi-component determination method in combination with chromatographic fingerprint analysis is suitable for quantitative analysis and quality control of S. sphenanthera.     

Ag@TiO2 Nanoprisms with Highly Efficient Near‐Infrared Photothermal Conversion for Melanoma Therapy

Melanoma is a primary reason of death from skin cancer and associated with high lethality. Photothermal therapy (PTT) has been developed into a powerful cancer treatment technique in recent years. Here, we created a low‐cost and high‐performance PTT agent, Ag@TiO₂ NPs, which possesses a high photothermal conversion efficiency of ≈65 % and strong near‐infrared (NIR) absorption about 808 nm. Ag NPs were synthesized using a two‐step method and coated with TiO₂ to obtain Ag@TiO₂ NPs by a facile sol‐gel method. Because of the oxide, Ag@TiO₂ NPs exhibit remarkable high photothermal conversion efficiencies and biocompatibility in vivo and in vitro. Cytotoxicity and therapeutic efficiency of photothermal cytotoxicity of Ag@TiO₂ NPs were tested in B16‐F10 cells and C57BL/6J mice. Under light irradiation, the elevated temperature causes cell death in Ag NPs‐treated (100 μg mL^?1) cells in vitro (both p<0.01). In the case of subcutaneous melanoma tumor model, Ag@TiO₂ NPs (100 μg mL^?1) were injected into the tumor and irradiated with a 808 nm laser of 2 W cm^?2 for 1 minute. As a consequence, the tumor volume gradually decreased by NIR laser irradiation with only a single treatment. The results demonstrate that Ag@TiO₂ NPs are biocompatible and an attractive photothermal agent for cutaneous melanoma by local delivery.     

Simultaneous determination of multiple platycosides with a single reference standard in Platycodi Radix by high‐performance liquid chromatography coupled with evaporative light scattering detection

A traditional external standard method using HPLC coupled with evaporative light scattering detection has been developed for fast and accurate determination of seven platycosides in Platycodi Radix. However, inevitable difficulties in reference standards preparation process, which are quite costly and time consuming, have made its application limited. To avoid this inconvenience, a simultaneous determination of multiple components with a single reference standard strategy, which could be realized by calibrating the standard curve with internal standard and response factors, was introduced to the HPLC coupled with evaporative light scattering detection method. This is the first time that an incorporation of these two methods has been realized. Among seven ingredients, platycodin D was selected as the internal standard for its relatively easy preparation and low cost. Moreover, according to the investigation on concentration‐dependent effects over response factors and robustness test, platycoside E, deapioplatycodin D, platycodin D, and polygalacin D₂ were chosen to be the indicators for this novel method. The present method has not shown statistically significant differences with a traditional external standard method as verified sample analysis by the F‐test (p = 95%, n = 6).     

Surface modification of fluorosilicone acrylate RGP contact lens via low-temperature argon plasma

A fluorosilicone acrylate rigid gas permeable (RGP) contact lens was modified via argon plasma to improve surface hydrophilicity and resistance to protein deposition. The influence of plasma treatment on surface chemical structure, hydrophilicity and morphology of RGP lens was investigated by X-ray photoelectron spectrometer (XPS), contact angle measurements and scanning electron microscope (SEM), respectively. The contact angle results showed that the hydrophilicity of the contact lens was improved after plasma treatment. XPS results indicated that the incorporation of oxygen-containing groups on surface and the transformation of silicone into hydrophilic silicate after plasma treatment are the main reasons for the surface hydrophilicity improvement. SEM results showed that argon plasma with higher power could lead to surface etching.     

Nanophotonic Device in Combination with Bacteriophages for Enhancing Detection Sensitivity of Escherichia coli in Simulated Wash Water

Among various approaches to control and monitor cross-contamination of fresh produce, a biosensor that can rapidly detect the presence of a specific bacterium in wash water or on fresh produce can be effective. This research demonstrates the development of a rapid biosensor based on a combination of a nanophotonic device and the bacteriophage T7 for the detection of Escherichia coli without the need for culturing or nucleic acid extraction. This biosensor platform is based on bacteriophage mediated specific lysis of target bacteria and release of β-galactosidase. The enzyme could be further detected by a nanophotonic device that amplifies the fluorescent signal, therefore allowing better sensitivity. Production of β-galactosidase is induced by isopropyl β-D-1-thiogalactopyranoside (IPTG) and the enzyme is then released by bacteriophage lysis, which is detected by the nanophotonic device using a fluorescent enzyme substrate resorufin β-D-galactopyranoside. Using this approach, the results demonstrated successful detection of 10 CFU mL^?1 of E. coli BL21 in simulated spinach wash water within 8?hours. Specificity of the assay was demonstrated with negative controls including Pseudomonas fluorescens and Listeria innocua.