A new intramolecular charge transfer receptor as a selective ratiometric ‘off-on’ sensor for Zn

A new intramolecular charge transfer (ICT) probe 3 is found to display a highly selective photophysical response in the presence of Zn²⁺, among various biologically significant metal ions examined. The absorption band of 3 is red shifted by 84 nm and the fluorescence intensity increases 13-fold in the presence of Zn²⁺. The binding interaction follows the order Zn²⁺ > Cd²⁺ > Mg²⁺ > Ba²⁺ > Ca²⁺ > K⁺ ≅ Na⁺ ≅ Li⁺ and the stability constant for 3 + Zn²⁺ is over an order of magnitude higher compared to biologically competing Ca²⁺ and Mg²⁺.     

Profiling the Photochemical-Induced Degradation of Rat Growth Hormone with Extreme Ultra-pressure Chromatography–Mass Spectrometry Utilizing Meter-Long Microcapillary Columns Packed with Sub-2-µm Particles

In recent years, protein therapeutics have seen increasing use in the therapeutic arena. As with traditional small molecule drug substances, one is obligated to ensure purity and stability of the various dosage forms. With these higher molecular weight therapeutics, a common approach for analytical characterization is enzymatic digestion followed by gradient elution liquid chromatography with mass spectrometry detection to create a peptide map (bottom-up protein analysis). Due to the difficulty to separate mixtures frequently encountered, there is the need for advanced chromatographic systems featuring increased resolution and/or peak capacity that can be operated in the gradient elution format. Presently, we describe an extreme ultra-pressure liquid chromatography (XUPLC) system that has been implemented as an in-house add-on to a commercial ultra-pressure chromatography system. This add-on allows operation at the 38 Kpsi range, accommodates the use of capillary columns in excess of 1 m packed with sub-2-µm particles and can be operated in the gradient elution format. To evaluate the utility of this system, rat growth hormone was used as a model protein and was exposed to light (λ 254 nm) to create a stress environment. When enzymatic digests of control and stressed protein were analyzed with the XUPLC system using MS detection, greater than 92% peptide coverage was achieved, including the identification some peptides where pre-oxidation of Met residues had occurred, as well as chemistry specifically related to the photolysis of protein disulfide linkages. When the same samples were analyzed by commercial UPLC and compared to the XUPLC results, the utility of the increased peak capacity available with the XUPLC was apparent as previously co-eluting peaks were now well resolved. In particular, one specific degradation route was identified where a pair of isobaric cis/trans diastereomerically related peptides were well resolved by XUPLC while they were unresolved by UPLC. Clearly the use of this system operating at a higher pressure regime with long capillary columns is and will be useful in continued investigations of protein stability, especially in cases where only subtle differences in the amino acid residues have occurred during degradation.     

A novel retro-reaction strategy toward designing a selective fluorescence Cu(II) chemodosimeter

A novel C9 acridane-adduct, featuring ketobenzimidazole chelate, functions as a highly selective fluorescent chemodosimeter for Cu²⁺, while other metal ions pose little interferences, if any. The signaling strategy operates via the Cu²⁺-mediated retro-reaction, generating a strongly fluorescent acridinium ion at the expense of the weakly emitting probe.     

Influence of multiwall carbon nanotubes on morphology and electrical conductivity of PP/ABS blends

Polypropylene (PP) and acrylonitrile‐butadiene‐styrene (ABS) blends with multiwall carbon nanotubes (MWNT) were prepared by melt mixing. PP/ABS blends without MWNT revealed coarse co continuous structures on varying the ABS content from 40 to 70 wt %. Bulk electrical conductivity of the blends showed lower percolation threshold (0.4–0.5 wt %) in the 45/55 co continuous blends whereas the percolation threshold was between 2 and 3 wt % in matrix‐particle dispersed morphology of 80/20 blends. Interestingly, droplet size was observed to decrease with addition of MWNT above percolation threshold in 80/20 blends. Further, the bulk electrical conductivity was found to be dependent on the melt flow index of PP. The non‐polar or weakly polar nature of blends constituents resulted in the temperature independent dielectric constant, dielectric loss, and DC electrical conductivity. Rheological analysis revealed the formation of 3D network‐like structure in 80/20 PP/ABS blends at 3 wt % MWNT. An attempt was made to understand the relationship between rheology, morphology, and electrical conductivity of these blends. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2286–2295, 2008     

Chickpea leaf exudates (CLE) mediated Knoevenagel–Michael reactions for the synthesis of diketodiols and biscoumarins

A green, highly efficient, and eco-friendly protocol for Knoevenagel–Michael addition reaction is reported in Chickpea leaf exudates (CLE) as a naturally sourced biosurfactant. The reactions between dimedone/4-hydroxycoumarins and a variety of aryl aldehydes were carried out in presence of CLE to afford diketodiols/biscoumarins. The synthetic pathway complies with several key requirements of green chemistry principles such as the employment of natural feedstock as green reaction media, ambient temperature, atom economy along with natural biosurfactant type Bronsted acids, and recyclable and biodegradable catalyst which led to a 28-fold increase in molar efficiency versus industrial standard protocols. Its dynamic phase is confirmed by the optical microscopy technique and critical micelle concentration measurement. The notable advantages of the present protocol were simple work-up procedure, high yield within short reaction time, easy separation of products, avoiding tedious column chromatography thus making the protocol environmentally friendly, sustainable, and economical.

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Recent advances of boron-doped diamond electrochemical sensors toward environmental applications

The electrocatalytic properties of boron-doped diamond (BDD) electrodes have been considered for a variety of sensing applications. The unusual electrochemical properties of BDD include a large potential window, a small background current, and better resistance to fouling than other carbon-based electrodes. The use of BDD for remediation and environmental sensing applications has recently attracted the interest of the sensor research community. This review focuses on recent developments that involve the use of BDD as an environmentally friendly sensing material for environmental analysis. The electrochemical properties of boron-doped diamond that has undergone surface modification (e.g., with metals or enzymes) will be considered. Recent achievements involving the use of BDD electrodes for detecting pesticides, mycotoxins, peroxides, and phenolic compounds are considered.     

Development of gel polymer electrolyte based on LiTFSI and EMIMFSI for application in rechargeable lithium metal battery with GO-LFP and NCA cathodes

Journal of Solid State Electrochemistry - In this paper, we report the effect of ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI) on polymer poly(ethylene oxide) (PEO)...     

Green Synthesis and Characterization of Silver Nanoparticles of Psidium guajava Leaf Extract and Evaluation for Its Antidiabetic Activity

Diabetes mellitus (DM) and its complications are a severe public health concern due to the high incidence, morbidity, and mortality rates. The present study aims to synthesize and characterize silver nanoparticles (AgNPs) using the aqueous leaf extract of Psidium guajava (PGE) for investigating its antidiabetic activity. Psidium guajava silver nanoparticles (PGAg NPs) were prepared and characterized by various parameters. The in vivo study was conducted using PGE and PGAg NPs in Streptozotocin (STZ)-induced diabetic rats to assess their antidiabetic properties. STZ of 55 mg/kg was injected to induce diabetes. The PGE, PGAg NPs at a dose of 200 and 400 mg/kg and standard drug Metformin (100 mg/kg) were administered daily to diabetic rats for 21 days through the oral route. Blood glucose level, body weight changes, lipid profiles, and histopathology of the rats’ liver and pancreas were examined. In the diabetic rats, PGE and PGAg NPs produced a drastic decrease in the blood glucose level, preventing subsequent weight loss and ameliorating lipid profile parameters. The histopathological findings revealed the improvements in pancreas and liver cells due to the repercussion of PGE and PGAg NPs. A compelling effect was observed in all doses of PGE and PGAg NPs; however, PGAg NPs exhibited a more promising result. Thus, from the results, it is concluded that the synthesized PGAg NPs has potent antidiabetic activity due to its enhanced surface area and smaller particle size of nanoparticles.