The water‐promoted Diels–Alder reaction in quaternary ammonium salts

Prevailing classification of salts based on their effect in solubility and stability of proteins in aqueous solution predicts that tetraalkylammonium salts, guanidinium chloride (GnCl), LiClO₄ act as salting‐in (S/I) and LiCl, NaCl act as salting‐out (S/O) in aqueous conditions. In the same context the behaviour of GnCl, LiClO₄ and LiCl are contradictory in polar solvents like ethylene glycol and formamide. In these solvents, expected salt effect shows just opposite nature from their usual expectation. However, in the aqueous solution salts like tetraalkylammonium halide (R₄NX, R = alkyl group, X = Br group) behave like salting‐in salts. The physicochemical origin of the salting in effect of R₄NX type of salts has been discussed elaborately in the present work. The role of cations in terms of substitution of various alkyl groups on R₄NX has been systematically presented here on the basis of experimental kinetic and thermodynamic studies. The abnormal behaviour of R₄NX salts in aqueous solution has also been explained by the Setschenov equation (k_s) and Δμ_solvation values, which highlights their individual nature out of common properties of R₄NX. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemical and Structural Properties of Drug–protein Nanocomposites Prepared by Pulsed Laser Deposition from Conjugated Targets

Nanostructured indomethacin (IM) – bovine serum albumin (BSA) composite particulates below 50 nm were obtained by pulsed laser deposition (PLD) with 1064 nm IR beam. IM and BSA powders were coground for up to 210 min to prepare conjugated targets for PLD with varying structural states. The ablation threshold was determined to be around 1.8 J/cm², from in situ monitoring of the deposited amount by a QCM sensor. The crystallinity of IM was preserved after PLD at 5 J/cm² and decreased with increasing the laser fluence. The non-crystalline state of IM in the target after prolonged cogrinding with BSA, was also preserved in the deposited film. FT-IR absorption bands due to amide I of BSA became sharper while preserving the peak top position after cogrinding with IM. Conversely, we observed broadening of the amide I bands by PLD. Preservation and change in the chemical and structural states of the conjugates after PLD is discussed in terms of the secondary structure of BSA and crystallinity of IM.     

Characterization of silanization and antibody immobilization on spin-on glass (SOG) surface

Most embedded optical waveguide biosensors require low dielectric optical material. The prerequisites for such applications include the selection of an appropriate material and effective bio-functionalization. Spin-on glass (SOG) is one of the preferred polymers that can be easily deposited. Further, the chemical properties of the polymer make it amenable for bio-functionalization. This paper reports a detailed study of a protocol for immobilization of antibodies on SOG for possible immunobiosensor applications. The effect of silanization at different pH values on the number of free and usable amine sites was quantified by fluorimetry. Contact angle measurements, ellipsometry, AFM, and fluorescence microscopy was used for assessing the surface properties at various stages of preparation, functionalization and biomolecule immobilization.     

A Rationally Designed Bimetallic Platinum (II)-Ferrocene Antitumor Agent Induces Non-Apoptotic Cell Death and Exerts in Vivo Efficacy

Despite phenomenal clinical success, the efficacy of platinum anticancer drugs is often compromised due to inherent and acquired drug resistant phenotypes in cancers. To circumvent this issue, we designed two heterobimetallic platinum (II)-ferrocene hybrids that display multi-pronged anticancer action. In cancer cells, our best compound, 2 , platinates DNA, produces reactive oxygen species, and has nucleus, mitochondria, and endoplasmic reticulum as potential targets. The multi-modal mechanism of action of these hybrid agents lead to non-apoptotic cell death induction which enables circumventing apoptosis resistance and significant improvement in platinum cross resistance profile. Finally, in addition to describing detail mechanistic insights, we also assessed its stability in plasma and demonstrate anticancer efficacy in an in vivo A2780 xenograft model. Strikingly, compared to oxaliplatin, our compound displays better tolerability, safety profile and efficacy in vivo.     

Design of Two Channel Biorthogonal Filterbanks using Euler Frobenius Polynomial

Journal of Signal Processing Systems - This paper presents a technique to design a new class of biorthogonal perfect reconstruction (PR) filterbanks. In this technique, we use Euler Frobenius...