A bilateral study for the establishment of comparability in the measurement of ethanol in bioethanol fuel using isotope dilution mass spectrometry

A bilateral comparative study between two metrology institutes was conducted for the determination of ethanol in bioethanol fuel by isotope dilution mass spectrometry. Measurement procedures were independently developed by the Health Sciences Authority (Singapore) and the National Institute of Metrology (People??s Republic of China). The methods used included headspace gas chromatography?Chigh-resolution mass spectrometry, headspace gas chromatography?Cmass spectrometry (GC-MS) and direct injection to GC-MS. An investigation of all potential sources of uncertainty, including a component of uncertainty due to the effect of using different instruments such as gas chromatography?Cflame ionization detector method, commonly adopted for the analysis of organic volatiles, was carried out. The results of the analyses are consistent within the associated measurement uncertainty of each laboratory, reported at approximately 95% confidence level.     

A Phthalocyanine–Peptide Conjugate with High In Vitro Photodynamic Activity and Enhanced In Vivo Tumor‐Retention Property

A novel zinc(II) phthalocyanine conjugated with a short peptide with a nuclear localization sequence, Gly‐Gly‐Pro‐Lys‐Lys‐Lys‐Arg‐Lys‐Val, was synthesized by click chemistry and a standard Fmoc solid‐phase peptide synthesis protocol. The conjugate was purified by HPLC and characterized with UV/Vis and high‐resolution mass spectroscopic methods. Both this compound and its non‐peptide‐conjugated analogue are essentially non‐aggregated in N,N‐dimethylformamide and can generate singlet oxygen effectively with quantum yields (Φ_Δ) of 0.84 and 0.81, respectively, relative to unsubstituted zinc(II) phthalocyanine (Φ_Δ=0.56). Conjugation of the peptide sequence, however, can enhance the cellular uptake, efficiency in generating intracellular reactive oxygen species, and photocytotoxicity of the phthalocyanine‐based photosensitizer against HT29 human colorectal carcinoma cells. The IC₅₀ value of the conjugate is as low as 0.21 μM . In addition, the conjugate shows an enhanced tumor‐retention property in tumor‐bearing nude mice. After 72 h post‐injection, the dye concentration in the tumor was significantly higher than that in other organs. The results suggest that this phthalocyanine–peptide conjugate is a highly promising photosensitizer for photodynamic therapy.     

High-efficiency pyrene-based blue light emitting diodes: aggregation suppression using a calixarene 3D-scaffold

An efficient blue light emitting diode based on solution processable pyrene-1,3-alt-calix[4]arene is demonstrated, providing a record current efficiency of 10.5 cd A(-1) in a simple non-doped OLED configuration. Complete suppression of pyrene aggregation in the solid state is achieved by controlling chromophore dispersion using the 1,3-alt-calix[4]arene scaffold.     

Cycloaddition reactions of imines with 3-thiosuccinic anhydrides: synthesis of the tricyclic core of martinellic acid

Arylthio-substituted succinic anhydrides undergo cycloaddition reactions with imines to produce gamma-lactams in high yield and with high diastereoselectivity. The origin of the selectivity is proposed to result from anion-pi repulsion in the transition state. The utility of this technique is demonstrated in a synthesis of the carbon framework common to the alkaloids martinellic acid and martinelline in five steps.     

A Glutathione‐Activated Phthalocyanine‐Based Photosensitizer for Photodynamic Therapy

A zinc(II) phthalocyanine substituted with a 2,4‐dinitrobenzenesulfonate group has been prepared. Its fluorescence emission and reactive oxygen species generation can be greatly enhanced by glutathione in phosphate‐buffered saline and inside MCF‐7 cells. This compound thus functions as a highly efficient molecular‐based activatable photosensitizer.     

A General Strategy for Site‐Directed Enzyme Immobilization by Using NiO Nanoparticle Decorated Mesoporous Silica

Mesoporous materials have recently gained much attention owing to their large surface area, narrow pore size distribution, and superior pore structure. These materials have been demonstrated as excellent solid supports for immobilization of a variety of proteins and enzymes for their potential applications as biocatalysts in the chemical and pharmaceutical industries. However, the lack of efficient and reproducible methods for immobilization has limited the activity and recyclability of these biocatalysts. Furthermore, the biocatalysts are usually not robust owing to their rapid denaturation in bulk solvents. To solve these problems, we designed a novel hybrid material system, mesoporous silica immobilized with NiO nanoparticles (SBA‐NiO), wherein enzyme immobilization is directed to specific sites on the pore surface of the material. This yielded the biocatalytic species with higher activity than free enzyme in solution. These biocatalytic species are recyclable with minimal loss of activity after several cycles, demonstrating an advantage over free enzymes.     

Detection of Panton-Valentine Leukocidin DNA from methicillin-resistant Staphylococcus aureus by resistive pulse sensing and loop-mediated isothermal amplification with gold nanoparticles

This report describes a novel diagnostic assay for rapid detection of the Panton-Valentine Leukocidin (PVL) toxin of methicillin-resistant Staphylococcus aureus (MRSA) utilizing resistive pulse sensing (RPS), loop-mediated isothermal DNA amplification (LAMP) in combination with gold nanoparticles (AuNPs). The PVL DNA from MRSA was specifically amplified by LAMP using four primers at one temperature (65 °C). The DNA products with biotin were then conjugated to a first AuNP1 (55 ± 2 nm) through biotin–avidin binding. A second AuNP2 (30 ± 1.5 nm) coated with a specific DNA probe hybridized with the LAMP DNA products at the loop region to enhance assay sensitivity and specificity, to generate supra-AuNP1-DNA-AuNP2 assemblies. Scanning electron microscopy confirmed the presence of these supra-assemblies. Using RPS, detection and quantitation of the agglomerated AuNPs were performed by a tunable fluidic nanopore sensor. The results demonstrate that the LAMP-based RPS sensor is sensitive and rapid for detecting the PVL DNA. This technique could achieve a limit of detection (LOD) up to about 500 copies of genomic DNA from the bacteria MRSA MW2 and the detection can be completed within two hours with a straightforward signal-to-readout setup. It is anticipated that this LAMP-based AuNP RPS may become an effective tool for MRSA detection and a potential platform in clinical laboratory to report the presence or absence of other types of infectious agents.     

New conjugates of calix[4]arenes bearing dipyridine and indolizine heterocycles

A simple route to introduce various heterocycles, derivatives of dipyridyls and indolizines on the lower rim of the para-tert-butylcalix[4]arene via ester bond formation to afford 1,3-disubstituted conjugates is described. The conformation of the new compounds and some intermolecular interactions are discussed on the basis of X-ray and NMR analyses. Preliminary complexation properties of some of the new tert-butylcalix[4]arene heterocyclic conjugates with Cu (II), Co (II) and Ni (II) were studied by means of UV–Vis titration.