Neat Protein–Polymer Surfactant Bioconjugates as Universal Solvents

Solvents, particularly those having low volatility, are of great interest for the biocatalytic synthesis of utility chemicals and fuels. We show novel and universal solvent-like properties of a neat and water-less polymer surfactant–bovine serum albumin (BSA) conjugated material (WL-PS<i>p</i>BSA). This highly viscous, nonvolatile material behaves as a liquid above its solid–liquid transition temperature (∼25–27 °C) and can be used as a solvent for variety of completely dry solutes of different sizes and surface chemistries. We show using a combination of optical microscopy and steady -state and time-resolved fluorescence spectroscopy that dry and powdered dyes (hydrophobic Coumarin 153 (C153)), enzymes (α-chymotrypsin (α-Chy)), or even 1 μm microparticles (diffusion coefficient ca. three orders slower than C153), can be solubilized and completely dispersed in the WL-PS<i>p</i>BSA solvent above 25 °C. While C153, irrespective of its mode of addition to WL-PS<i>p</i>BSA, binds similarly to BSA, α-Chy can be stabilized and activated to perform its hydrolysis function, even at 100 °C. This work therefore provides insights into the form of universal solvent characteristic property for this new class of nonaqueous, nonvolatile, biodegradable protein–polymer surfactant-based conjugated materials and suggests potential new avenues that can have a huge impact on biocatalysis, bionanotechnology, drug delivery, and other applications

Modulation of Small Molecule Induced Architecture of Cyclodextrin Aggregation by Guest Structure and Host Size

A small molecule based on bisphenylethynyl amide meta linked to 2,6-pyridine can induce cyclodextrin (CD) aggregation through a possible 1:3 guest–host motif. Most of the small molecules induce CD nanotubular bundles principally through 1:2 guest–host unit capsules and aggregate through hydrogen bonding among the hydroxyl groups present on the rims of the CD molecules. The <i>N</i>,<i>N</i>-dimethyl aminopropyl carboxamide side chain and the central pyridine ring of 6-bromo-2-phenylethylaminopyridine (BPEAP) induces nanotubular bundles with α-CD and laminar bundles with β- and γ-CDs, which, as a consequence, may result in formation of pores in the aggregates that can find wide applications in biological storage machinery. The stoichiometry of the ingredients of the unit capsules has been evidenced by Job’s plot. The size-dependent suprastructures induced by BPEAP have been studied by steady state and time-resolved fluorescence spectroscopy and atomic force microscopy

Synthesis and characterization of Nanocrystalline Ba0.6Sr0.4Co0.8Fe0.2O3 for application as an efficient anode in solid oxide electrolyser

Nanocrystalline Ba0.6Sr0.4Co0.8Fe0.2O3 (BSCF-6482) powder is synthesized by combustion synthesis technique. Powder calcined at 1000 degrees C reveals phase pure cubic perovskite. Transmission electron microscopic (TEM) analysis exhibits soft agglomerates of average size similar to 50 nm wherein interplanar spacing for (110) and (221) resembles to the cubic lattice. While DC electrical conductivity of 23 S cm(-1)@800 degrees C is observed, interfacial polarization measured by electrochemical impedance spectroscopy is found to be the least 850 degrees C (0.18 Omega cm(2)). Cell performance has been compared among BSCF-6482, BSCF-5582 and LSCF-6482 mixed ionic and electronic conducting (MIEC) and conventional electrode (LSM). Higher performance (1.37 A/cm(2)@1.3 V,800 degrees C) with high hydrogen generation rate (0.57 Nl/cm(2)/h) is found during steam electrolysis with cell fabricated using BSCF-6482 having minimal area specific resistance 0.33 Omega cm(2). Under similar operating condition, BSCF-5582, LSCF-6482 and LSM exhibit hydrogen generation rate of 0.35, 0.28 and 0.23 Nl/cm(2)/h respectively. Cell microstructure is clinically correlated with the higher reactivity of BSCF-6482 air electrode in steam electrolysis. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Synergic Influence of Reverse Micelle Confinement on the Enhancement in Photoinduced Electron Transfer to and from Carbon Nanoparticles

The photoexcited behavior of carbon nanoparticles (CNPs) and the effect of confinement on photoinduced electron transfer (PET) to and from the CNPs have been examined by confining the nanoparticles and electron donor–acceptor systems in aerosol OT (AOT)/hexane/water reverse micelles (RMs). The CNPs and the electron donor dimethylaniline (DMA) are captured in the nonpolar environment of the RMs, while methyl viologen (MV²⁺), the electron acceptor, readily goes into the water pool. This confined medium facilitates experimentation on the electron transfer dynamics between two different phases. PET from DMA to MV²⁺ via CNPs is the expected phenomenon. The ultrafast photogenerated MV^•+ cation radical acts as an electron sink scavenging electrons from DMA. PET has been confirmed from steady-state and time-resolved fluorescence along with ultrafast transient absorption measurements. The kinetic details of PET in the DMA–CNP–MV²⁺ assembly in a confined RM medium provide prospects toward development of light energy conversion devices

Green Synthesis and Reversible Dispersion of a Giant Fluorescent Cluster in Solid and Liquid Phase

A water-soluble highly fluorescent silver cluster on Au­(I) surface has been synthesized with green chemistry under sunlight. The evolution of the silver cluster is synergistic, demanding gold and glutathione. The fluorescent Au­(I)_core–Ag­(0)_shell particles are huge in size and at the same time they are robust. That is why they become a deliverable fluorescing solid upon drying. Again, the giant particles run into common water miscible solvents. As a result, the fluorescence intensity increases to a great extent without any alteration of emission maxima. In this respect, acetone has been found to be the best-suited solvent. To have a universal applicability of the fluorescent clusters, the particles in the water pool of a reverse micelle have been prepared to transfer the particles into different water immiscible solvents. The comparatively lower fluorescence intensity of the particles has been ascribed to a space confinement effect. Finally, giant-cluster-impregnated yellow-orange fluorescent polymer film and fluorescent cotton wool, as well as paper substrate, have been prepared. The antibacterial activity of the fluorescent particle has also been tested involving modified cotton wool and paper substrate for Gram-negative and -positive Escherichia coli and Staphylococcus aureus, respectively