Simple Michael acceptor type coumarin derived turn-on fluorescence probes to detect cyanide in pure water

The present article describes design and synthesis of coumarin derived chemical reaction based chemodosimeter to recognize cyanide in aqueous medium. The Michael acceptor type coumarin derived probes 3 and 4 upon interaction with cyanide undergo Michael type nucleophilic addition reaction to form adducts in which fluorescence intensity was significantly enhanced, ‘turn-on’ by the change in intramolecular charge transfer (ICT) mechanism. The nonfluorescent color of solutions changed to a naked-eye sensitive fluorescent blue (switched-on). Job’s plot analysis revealed a 1:1 stoichiometry for the interaction between the probe and cyanide anion with a high detection limit.     

Recent Progress,Challenges and Prospects in Monitoring Plastic-Derived Xenoestrogens Using Molecularly Imprinted Sorbents

Indoor and outdoor exposure to plastic-derived xenoestrogens, such as phthalates and phenolic compounds, can adversely affect endocrine and reproductive systems in humans and wildlife. To accomplish the extraction of plastic-derived xenoestrogens from environmental samples, molecularly imprinted polymers (MIPs) have been proved to be selective, efficient, and reliable sorbents. Despite some problems associated with the use of MIPs as sorbents, these have been found to be of considerable interest due to their advantages of selectivity, easy synthetic procedures, and better stability over commercially available solid sorbents. Modifications in their synthetic strategies are continuously in progress and new approaches are being made through graphene oxide substrates, nanostructured platforms, nanoferrites, cryogels, and co-electropolymerization to design better sorbents. Apart from this, efforts to create molecularly imprinted solid phase microextraction (SPME) fibers have also been successful in improving the efficiency of the methodology. In future, the use of MIPs developed from advanced synthetic strategies, or as sorbents for more robust techniques like SPME and microextraction on packed sorbents, will add new horizons to explore the potential of MIPs in the field of plastic-derived xenoestrogens. This review presents various challenges, as well as progress and prospects associated with the extraction of plastic-derived phthalates and phenolic compounds using molecularly imprinted sorbents.     

Sustained release drug delivery using supramolecular hydrogels of the triblock copolymer PCL–PEG–PCL and α-cyclodextrin

Supramolecular hydrogels (SMGel) have attracted much attention as a drug and gene delivery system in recent years. In this study, SMGels based on the tri-block copolymer of poly-ε-caprolactone–polyethylene glycol–poly-ε-caprolactone (PCL–PEG–PCL) and α-cyclodextrin (α-CD) were prepared and evaluated for the delivery of two model drugs, naltrexone hydrochloride and vitamin B₁₂. Tri-block copolymers were synthesized easily in 15 min by ring-opening polymerization using the microwave irradiation technique, and their structures were determined by gel permeation chromatography and nuclear magnetic resonance methods. SMGels composed of various concentrations of the copolymer and α-CD were prepared and characterized for their rheological behaviour, their gel formation time and in vitro drug release profile. The results indicated that copolymers with a PCL to PEG ratio of 1:4 are suitable for SMGel preparation. The most viscose system with good syringeability was prepared by mixing 12 % wt α-CD and 10 % wt of copolymer. The gelation was found to occur within a minute after mixing. The viscosity of the hydrogel systems was determined as a function of shear rate. Finally, in vitro B₁₂ release through the hydrogel systems was studied. Up to 80 % of Vitamin B₁₂ was released through this system during a period of 20 days. Rheological evaluation revealed that the hydrogel has shear thinning properties, and the system regained its ground rheological state in a time dependent manner. Polymer concentration did not affect the drug release profiles. Finally, it was concluded that such systems are appropriate drug delivery systems due to their ability to provide a controlled drug release profile and their shear thinning thixotropic behaviour, which makes them syringeable and injectable.     

A facile and convenient method for synthesis of alkyl thiocyanates under homogeneous phase transfer catalyst conditions

A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide （TBAB） as a phase transfer catalyst. The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields. No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.     

'Living cantilever arrays' for characterization of mass of single live cells in fluids

The size of a cell is a fundamental physiological property and is closely regulated by various environmental and genetic factors. Optical or confocal microscopy can be used to measure the dimensions of adherent cells, and Coulter counter or flow cytometry (forward scattering light intensity) can be used to estimate the volume of single cells in a flow. Although these methods could be used to obtain the mass of single live cells, no method suitable for directly measuring the mass of single adherent cells without detaching them from the surface is currently available. We report the design, fabrication, and testing of 'living cantilever arrays', an approach to measure the mass of single adherent live cells in fluid using silicon cantilever mass sensor. HeLa cells were injected into microfluidic channels with a linear array of functionalized silicon cantilevers and the cells were subsequently captured on the cantilevers with positive dielectrophoresis. The captured cells were then cultured on the cantilevers in a microfluidic environment and the resonant frequencies of the cantilevers were measured. The mass of a single HeLa cell was extracted from the resonance frequency shift of the cantilever and was found to be close to the mass value calculated from the cell density from the literature and the cell volume obtained from confocal microscopy. This approach can provide a new method for mass measurement of a single adherent cell in its physiological condition in a non-invasive manner, as well as optical observations of the same cell. We believe this technology would be very valuable for single cell time-course studies of adherent live cells.     

Plasma activated water: the next generation eco-friendly stimulant for enhancing plant seed germination,vigor and increased enzyme activity,a study on black gram (Vigna mungo L.)

Plasma Chemistry and Plasma Processing - Chemical fertilization in agriculture is threatening to the ecosystem. Therefore, the use of eco-friendly stimulant for crop revolution is highly desirable....     

Synthesis of phthalazine compounds using heterogeneous base catalyst based on silica nanoparticles obtained from rice husk

Research on Chemical Intermediates - In this study, the nanoparticles of amorphous silica were easily extracted from low-cost rice husk ash. They were functionalized with 3-(chloropropyl)...     

Characterization and differentiation of iron ores using X-ray diffractometry,k0 instrumental neutron activation analysis and inductively coupled plasma optical emission spectrometry

This study was aimed at developing methodology for the characterization and differentiation of iron ores from different ore deposits. X-ray diffractometry (XRD) was used for the determination of major and minor chemical phases in the ores, k₀-instrumental neutron activation analysis (k₀-INAA) and inductively coupled plasma optical emission spectrometry (ICP-OES) were employed for the determination of elemental profiles of iron ores. The quality of the ores was evaluated to establish their suitability to serve as a raw material for iron production. Principal component analysis was performed on the elemental data for the classification of ores. It was also shown that ores can be differentiated on the basis of rare earth elemental profiles. In this paper a new indicator, based on four elements (Ca, S, Sb, Yb), was proposed for the classification.

     

The sporothriolides. A new biosynthetic family of fungal secondary metabolites

The biosynthetic gene cluster of the antifungal metabolite sporothriolide 1 was identified from three producing ascomycetes: Hypomontagnella monticulosa MUCL 54604, H. spongiphila CLL 205 and H. submonticulosa DAOMC 242471. A transformation protocol was established, and genes encoding a fatty acid synthase subunit and a citrate synthase were simultaneously knocked out which led to loss of sporothriolide and sporochartine production. In vitro reactions showed that the sporochartines are derived from non-enzymatic Diels–Alder cycloaddition of 1 and trienylfuranol A 7 during the fermentation and extraction process. Heterologous expression of the spo genes in Aspergillus oryzae then led to the production of intermediates and shunts and delineation of a new fungal biosynthetic pathway originating in fatty acid biosynthesis. Finally, a hydrolase was revealed by in vitro studies likely contributing towards self-resistance of the producer organism.

A new family of fungal biosynthetic pathways is elucidated based on the use of fatty acid and citrate-like intermediates.

Gamma-lactone and alkyl citrate compounds derived from oxaloacetate are widespread natural products in fungi and often possess potent biological activities. Examples include sporothriolide 1,^1,2 piliformic acid 2,³ tyromycin 3⁴ and the cyclic maleidrides including byssochlamic acid 4^5,6 among others (Fig. 1). In some cases, for example those of 4 and squalestatin S1 5,⁷ detailed molecular studies have revealed that a dedicated polyketide synthase (PKS) produces a carbon skeleton that is then condensed with oxaloacetate by a citrate synthase (CS) to give an early alkyl citrate intermediate that is further oxidatively processed. In other cases, such as 1 and the sporochartines 6, the biosynthetic pathways are not yet clear.Open in a separate windowFig. 1Structures of γ-lactone and alkyl citrate metabolites from fungi. Bold bonds show oxaloacetate-derived carbons where known.Sporochartines 6a–6d^8,9 from the fungus Hypoxylon monticulosum CLL 205 (now referred to as Hypomontagnella spongiphila)¹⁰ possesses potent cytotoxicity (IC₅₀: 7.2 to 21.5 μM) vs. human cancer cell lines and are proposed to be Diels Alder (DA) adducts of the furofurandione sporothriolide 1, itself a potent antifungal agent (EC₅₀: 11.6 ± 0.8 μM),¹¹ and trienylfuranol A 7,¹² originally obtained from an endophytic fungus Hypoxylon submonticulosum DAOMC 242471 (now referred to as Hypomontagnella submonticulosa).¹³ Since the biosynthesis of sporothriolide 1 and related compounds is unknown, and biological DA reactions in fungi are currently of high interest,¹⁴ we decided to examine the biosynthesis of the sporochartines 6 in the Hypomontagnella spp. strains MUCL 54604 and CLL 205 (ref. 10 and 13) in detail.