Ion- Beam Modification of Peo Based Polymer Electrolytes

In this paper, we report the ion beam interaction with a well explored ion conducting polymer electrolyte, viz., polyethylene oxide complexed with sodium iodide (PEO:NaI). Li³⁺ ions at 50 MeV were bombarded on the film at different flux. The conductivity modulation of the films has been reported due to interaction at different fluence. The increase in the total conductivity is explained in terms of the change in the number of charge carriers and the dielectric constant of the polymer electrolyte films.     

A new method for microcapsule characterization: use of fluorogenic genipin to characterize polymeric microcapsule membranes

Numerous microcapsule systems have been developed for a wide range of applications, including the sustained release of drugs, cell transplantation for therapy, cell immobilization, and other biotechnological applications. Despite the fact that microcapsule membrane is a dominant factor governing overall microcapsule performance, its characterization is challenging. We report a new method for characterizing microcapsule membranes, using the most common alginate-poly-L-lysine-alginate (APA) microcapsule as an example. Our data demonstrate that genipin, a naturally derived reagent extracted from gardenia fruits, interacts with poly-L-lysine (PLL) and generates fluorescence. This fluorescence allows clear visualization and easy analysis of the PLL membrane in the APA microcapsules using confocal laser scanning microscopy. The results also show that PLL binding correlates to the reaction variables during PLL coating such as PLL concentration and coating time. In addition, five other different microcapsule formulations consisting of PLL and/or chitosan membranes were examined, and the results imply that this method can be extended to characterize a variety of microcapsule membranes. These findings suggest that genipin can serve as a fluorogenic marker for rapid characterization of microcapsule membranes, a superior method that would have important implications for microcapsule research and potential in many other applications.     

Synthesis and characterization of metal-centered, six-membered, mixed-valent, heterometallic wheels of iron, manganese, and indium

Heptanuclear metal-centered, six-membered, mixed-valent, heterometallic wheels 1-3 of iron, manganese, and indium were prepared in a one-pot reaction from N-benzyldiethanolamine (H2L(1)), cesium carbonate, [PPh4]2[MnCl4], and FeCl3 or InCl3. All three complexes were characterized by the combination of elemental analysis, FAB mass spectroscopy, X-ray diffraction and cyclic voltammetry and in the case of 1 additionally by M?ssbauer spectroscopy. In 1, four Mn(II) ions in the periphery are arranged in pairs alternating with one Fe(III) ion each, with an Fe(III) ion located in the center. In 2, three Mn(II) ions alternate with three In(III) ions, whereas in 3, four In(III) ions are arranged in pairs and alternate with one Mn(II) ion each. In 2 and 3 an Mn(II) ion is encapsulated in the center.     

Monitoring phagocytic uptake of amyloid β into glial cell lysosomes in real time

Phagocytosis by glial cells is essential to regulate brain function during health and disease. Therapies for Alzheimer''s disease (AD) have primarily focused on targeting antibodies to amyloid β (Aβ) or inhibitng enzymes that make it, and while removal of Aβ by phagocytosis is protective early in AD it remains poorly understood. Impaired phagocytic function of glial cells during later stages of AD likely contributes to worsened disease outcome, but the underlying mechanisms of how this occurs remain unknown. We have developed a human Aβ_1–42 analogue (Aβ^pH) that exhibits green fluorescence upon internalization into the acidic organelles of cells but is non-fluorescent at physiological pH. This allowed us to image, for the first time, glial uptake of Aβ^pH in real time in live animals. We find that microglia phagocytose more Aβ^pH than astrocytes in culture, in brain slices and in vivo. Aβ^pH can be used to investigate the phagocytic mechanisms responsible for removing Aβ from the extracellular space, and thus could become a useful tool to study Aβ clearance at different stages of AD.

Glial cell phagocytosis of pH-dependent amyloid-β, Aβ^pH, in live and fixed cultures, brain tissue sections, retina, cortex and in live animals useful for studying function in health and disease.     

Structural characterization of forced degradation products of empagliflozin by high resolution mass spectrometry

Eleven unique degradation products (DPs) of empagliflozin (EGF), a sodium glucose cotransporter (SGLT) 2 inhibitor have been reported for the first time. These DPs were generated as per International Conference on Harmonization (ICH) guidelines Q1 (R2) using stress conditions such as acid, base hydrolysis and oxidative environment. The sum of 12 DPs have been successfully resolved by Ultra-High Performance Liquid Chromatography-Mass Spectrometry (UHPLC-MS) method involving Eclipse plus C₁₈ RRHD (2.1?×?50?mm, 1.8µm) column and mobile phase comprising of water with 0.1% formic acid and methanol in 1:1 quotient. Structure of DPs and the degradation pathways have been proposed on the basis of accurate mass and MS/MS fragmentation pattern acquired through Liquid Chromatography-Electrospray Ionization Quadrupole Time of Flight Mass Spectrometer (LC-ESI-QTOF-MS). It has been observed that maximum DPs were formed during acid hydrolysis and the major ones were (2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-(((S)-1,4-dihydroxybutan-2-yl)oxy)benzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (DP1) and (2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-hydroxybenzyl)phenyl)-6-(hydroxymethyl) tetrahydro-2H-pyran-3,4,5-triol (DP2) generated due to ring opening of tetrahydrofuran moiety and elimination of tetrahydrofuran ring respectively. The proposed structures of DPs and their associated pathways will be essential for optimization of manufacturing and quality control parameters of EGF.     

Comparison of dye (oxazine and thiazine) materials as a photosensitizer for use in photogalvanic cells based on molecular interaction with sodium dodecyl sulphate by spectral study

The photochemistry of dye is playing a significant role for understanding the mechanism of electron transfer reactions in photoelectrochemical devices such as photogalvanic cells, DSSC, semiconductor photo-catalysis, photoconductors, etc. Oxazines (Brilliant Cresyl Blue and Nile Blue O) and thiazines (Azur A, Azur B, Azur C, Methylene Blue and Toluidine Blue O) dyes have been used widely as a photosensitizer with and without surfactants in the photogalvanic cells for solar power conversion and storage. Since, the stability and solubility of photosensitizers (dyes) are increased in the presence of surfactant and these properties lead to enhance the electrical output of the photogalvanic cells. Therefore, here we have studied the extent of interaction of different dyes with sodium dodecyl sulphate (SDS), find out the order of stability of dye–SDS on the basis of magnitudes of shifting in λ_max of dye monomer and try to correlate order of dye–SDS interaction with already reported electrical output data of photogalvanic cells. Brilliant Cresyl Blue, Nile Blue O, Azur A and TB O have shown red shifting while Azur B, Azur C and MB have shown blue shifting in their λ_max value with SDS, which indicates formation of dye–surfactant complex. But, the extent of formation of complex for different dyes with SDS was different due to change in their alkyl groups. Dyes with red shifting have greater stability in excited state as well as higher electrical output data of the cell than dye with blue shifting. On the basis of both red and blue shifting, order of stability of dyes–SDS complex was found as: Brilliant Cresyl Blue?>?Toluidine Blue O?>?Azur A?>?Nile Blue?>?Azur B?>?Methylene Blue?>?Azur C. The order of electrical output values of these dyes in photogalvanic cells have also been supported by literature data in the presence of SDS. Hence, the dye–surfactant complex which would have greater stability in excited state might be more useful for improvement of conversion efficiency and storage capacity of photogalvanic cells in the future.     

Extracellular Surface Potential Mapping by Scanning Ion Conductance Microscopy Revealed Transient Transmembrane Pore Formation Induced by Conjugated Polymer Nanoparticles

In‐depth understanding of the biophysicochemical interactions at the nano–bio interface is important for basic cell biology and applications in nanomedicine and nanobiosensors. Here, the extracellular surface potential and topography changes of live cell membranes interacting with polymeric nanomaterials using a scanning ion conductance microscopy‐based potential imaging technique are investigated. Two structurally similar amphiphilic conjugated polymer nanoparticles (CPNs) containing different functional groups (i.e., primary amine versus guanidine) are used to study incubation time and functional group‐dependent extracellular surface potential and topographic changes. Transmembrane pores, which induce significant changes in potential, only appear transiently in the live cell membranes during the initial interactions. The cells are able to self‐repair the damaged membrane and become resilient to prolonged CPN exposure. This study provides an important observation on how the cells interact with and respond to extracellular polymeric nanomaterials at the early stage. This study also demonstrates that extracellular surface potential imaging can provide a new insight to help understand the complicated interactions at the nano–bio interface and the following cellular responses.     

Metal‐Organic Frameworks as Platform for Lewis‐Acid‐Catalyzed Organic Transformations

Metal‐organic frameworks (MOFs) are highly promising Lewis acid catalysts; they either inherently possess Lewis acid sites (LASs) on it or the LASs can be generated through various post‐synthetic methods, the later can be performed in MOFs in a trivial fashion. MOFs are suitable platform for catalysis because of its highly crystalline and porous nature. Moreover, with recent advancements, thermal and chemical stability is not a problem with many MOFs. In this Minireview, an enormous versatility of MOFs, in terms of their microporosity/mesoporosity, size/shape selectivity, chirality, pore size, etc., has been highlighted. These are advantageous for designing and performing various targeted organic transformations. Although, many organic transformations catalyzed by MOFs with LASs have been reported in the recent past. In this Minireview, we have restricted ourselves to four important organic reactions: (i) cyanosilylation, (ii) Diels–Alder reaction, (iii) C?H activation, and (iv) CO₂‐addition. The discussion focuses mostly on the recent reports (42 examples).     

Sequential detection of Cu2+ and cysteine using an imidazole‐based chemosensor in aqueous solution

A highly substituted imidazole‐based colorimetric and fluorogenic chemosensor, 2‐methoxy‐4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)phenol (L), for the detection of Cu²⁺ ion and subsequent colorimetric detection of an amino acid, cysteine, was investigated. L exhibited a distinct color change from colorless to red in the presence of Cu²⁺ in an aqueous medium. The L‐Cu²⁺ complex can also be used to detect cysteine by the naked eye over a series of amino acids. The receptor L behaves as a highly selective colorimetric and fluorescent sensor for Cu²⁺ ions at concentrations as low as 4.33 and 2.25 μM, respectively. These values are much less compared to the WHO recommended limit of 30 μM for Cu²⁺ in drinking water. From Job's plot and the ESI‐MS spectrum, a 1:1 stoichiometric complex between L and Cu²⁺ ions can readily be reckoned. This binding was also substantiated by the EPR spectrum and magnetic susceptibility measurements. Additionally, the binding of L with Cu²⁺ ions was also manifested in the detection of B16F10 cells. This was substantiated through fluorescence microscopy. The spectrum of the L‐Cu²⁺ entity was also attempted to reproduce theoretically. The probable structure of this was also propounded through Density Functional Theory.     

ZnO Nanocatalyst Mediated Convergent Synthesis of Highly Substituted Imidazole and Imidazole‐derived Bi‐heterocyclic Scaffolds as Potential Antibacterial Agents

A new series of novel highly substituted imidazole and imidazole bi‐heterocycles have been synthesized via atom economic, one‐pot condensation reaction using benzil, substituted benzaldehydes, various amine scaffolds, and ammonium acetate using ZnO nanoparticles as effective catalyst. Simple operation, cheap catalyst, good to excellent yield, etc, are some of the advantages of this protocol. The characterization of the synthesized imidazole analogues was performed by Fourier transform infrared, nuclear magnetic resonance (¹H and ¹³C), mass analysis, and elemental analysis. The structures were unequivocally confirmed by single‐crystal X‐ray diffraction analysis. Synthesized compounds were tested for antibacterial activities by resazurin reduction assay. All compounds tested showed significant activity against bacteria. Among the 24 compounds tested, compounds 1c , 1i , 2c , 2g , and 3a proved to be more active against the bacterial strain tested.