Participation of compact planar 1,3,5-tri(buta-2,3-dien-1-yl)-1,3,5-triazinane-2,4,6-trione in Pd(0) catalysed seven component cascade reactions delivers novel tunable molecular architecture

We report the spatially controlled, protecting group free, catalytic assembly of a library of nineteen 7-component cascade products generated from a novel planar trisallenyl 1,3,5-triazinane-2,4,6-trione core in combination with aryl iodides and amines with excellent regio and good stereoaselectivity for Z,Z,Z-isomers.     

A High‐Throughput Assay for Arylamine Halogenation Based on a Peroxidase‐Mediated Quinone–Amine Coupling with Applications in the Screening of Enzymatic Halogenations

Arylhalides are important building blocks in many fine chemicals, pharmaceuticals and agrochemicals, and there has been increasing interest in the development of more “green” halogenation methods based on enzyme catalysis. However, the screening and development of new enzymes for biohalogenation has been hampered by a lack of high‐throughput screening methods. Described herein is the development of a colorimetric assay for detecting both chemical and enzymatic arylamine halogenation reactions in an aqueous environment. The assay is based on the unique UV/Vis spectrum created by the formation of an ortho‐benzoquinone‐amine adduct, which is produced by the peroxidase‐catalysed benzoquinone generation, followed by Michael addition of either a halogenated or non‐halogenated arylamine. This assay is sensitive, rapid and amenable to high‐throughput screening platforms. We have also shown this assay to be easily coupled to a flavin‐dependent halogenase, which currently lacks any convenient colorimetric assay, in a “one‐pot” workflow.     

A Target Recycling Amplification Process for the Digital Detection of Exosomal MicroRNAs through Photonic Resonator Absorption Microscopy

Exosomal microRNAs (miRNAs) have considerable potential as pivotal biomarkers to monitor cancer development, dis-ease progression, treatment effects and prognosis. Here, we report an efficient target recycling amplification process (TRAP) for the digital detection of miRNAs using photonic resonator absorption microscopy. We achieve multiplex digital detection with sub-attomolar sensitivity in 20 minutes, robust selectivity for single nucleotide variants, and a broad dynamic range from 1 aM to 1 pM. Compared with traditional qRT-PCR, TRAP showed similar accuracy in profiling exosomal miRNAs derived from cancer cells, but also exhibited at least 31-fold and 61-fold enhancement in the limits of miRNA-375 and miRNA-21 detection, respectively. The TRAP approach is ideal for exosomal or circulating miRNA biomarker quantification, where the miRNAs are present in low concentrations or sample volume, with potentials for frequent, low-cost, and minimally invasive point-of-care testing.     

Alkyl and aryl dicationic derivatives of cyclic triphosphenium ions

Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by (31)P NMR spectroscopy. The crystal and molecular structures of five such derivatives have been ascertained for the first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P-P bond lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium ions, where structural determinations have shown that the P-P bond lengths are intermediate between single and double bonds.     

Harvesting a logistic population in a slowly varying environment

The classic problem for a logistically evolving single species population being harvested involves three parameters: rate constant, carrying capacity and harvesting rate, which are taken to be positive constants. However, in real world situations, these parameters may vary with time. This paper considers the situation where these vary on a time scale much longer than that intrinsic to the population evolution itself. Application of a multiple time scale approach gives approximate explicit closed form expressions for the changing population, that compare favorably with those generated from numerical solutions.     

Microfluidic assembly of homogeneous and Janus colloid-filled hydrogel granules

The microfluidic assembly of colloid-filled hydrogel granules of varying shape and composition is described. First, drops are formed by shearing a concentrated colloidal microsphere-acrylamide suspension in a continuous oil phase using a sheath-flow device. Both homogeneous and Janus (hemispherically distinct) spheres and disks are produced by confining the assembled drops in microchannels of varying geometry. Next, photopolymerization is carried out shortly after drop breakup to preserve their morphology. Representative wet and dried granules are characterized using fluorescence and scanning electron microscopy, respectively. Our approach offers a facile route for assembling colloid-filled hydrogel granules with controlled shape and composition.