Optical imaging and magnetophoresis of nanorods

Peclet number analysis is performed to probe the convective motion of nanospheres and nanorods under the influence of magnetophoresis and diffusion. Under most circumstances, magnetophoretic behaviour dominates diffusion for nanorods, as the magnetic field lines tend to align the magnetic moment along the rod axis. The synthesis and dispersion of fluorophore-tagged nanorods are described. Fluorescence microscopy is employed to image the nanorod motion in a magnetic field gradient. The preliminary experimental data are consistent with the Peclet number analysis.     

Evolution of concentration fluctuation during phase separation of polystyrene/poly(vinyl methyl ether) blend in the presence of nanosilica

The influence of nanosilica on the concentration fluctuation of polystyrene/poly (vinyl methyl ether) (PS/PVME) mixtures was investigated during phase separation. The amplitude of concentration fluctuation was quantified by dielectric spectrums based on the idea of Lodge–Mcleish model and the linearized Cahn–Hilliard theory could describe the amplitude evolution of concentration fluctuation at the early stage of phase separation. Hydrophilic nanosilica A200 dispersed in PVME‐rich phase behaved an obvious inhibition effect on the concentration fluctuation of blend matrix, while hydrophobic nanosilica R974 dispersed in PS‐rich phase had little effect on the concentration fluctuation. The kinetics and amplitude evolution of concentration fluctuation during phase separation for PS/PVME/A200 nanocomposites were remarkably restrained due to the surface adsorption of PVME on A200. As the segmental dynamics of PVME and PS in homogeneous matrix was hardly influenced by A200 and R974, the enhanced miscibility and the significantly constrained flow relaxation of PVME chains might contribute to the retarded concentration fluctuation of PS/PVME/A200 nanocomposites. While the weak interaction between R974 and components of blend matrix and little effect of R974 on the molecular dynamics of PS chains may result in the weak retardation of concentration fluctuation for blend matrix. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1337–1349     

Sulfonic acid supported on magnetic nanoparticle as an eco‐friendly,durable and robust catalyst for the synthesis of β‐amino carbonyl compounds through solvent free Mannich reaction

A simple, efficient and environmentally benign solid acid catalyst was prepared by anchoring a propyl sulfonic acid on the surface of silica‐coated magnetic nanoparticles by low cost precursors. The catalyst has been then engaged in the efficient β‐amino carbonyl compounds production via three component Mannich reaction under solvent free reaction condition at room temperature. After the completing the reaction, the catalyst was readily separated by external magnet and reused for 10 successive rounds of reaction, without any significant loss in catalytic efficiency. The solid acidic system presented reusable strategy for the efficient synthesis of β‐amino carbonyl compounds, simplicity in operation, and green aspects by avoiding toxic conventional catalysts under solvent‐free condition.     

Tetramethylguanidinium‐polyallylamine (Tmg‐PA): A new class of nonviral vector for efficient gene transfection

Highly toxic polyallylamine (PA) was reacted with a varying amount of a novel linker, 6‐(N,N,N′,N′‐tetramethylguanidinium chloride) hexanoic acid (Tmg‐HA), to prepare a series of tetramethylguanidinium‐PA (Tmg‐PA) polymers, which were used as vectors for gene transfection. The extent of attachment of the linker, Tmg‐HA, to the PA backbone was determined by 2,4,6‐trinitrobenzene sulfonic acid assay. The modified polymers (Tmg‐PAs), when complexed with pDNA, exhibited good condensation ability. The nanoparticles, so formed, were characterized by their size and zeta potential and were subsequently evaluated for their toxicity and transfection ability on various mammalian cells, viz., HeLa, CHO, and HEK 293 cells. Mobility shift assay revealed that on increasing the percent substitution of Tmg‐HA onto PA (from Tmg‐PA1 to Tmg‐PA6), relatively higher amounts of modified polymers were required to retard the mobility of a fixed amount of DNA. Besides, Tmg‐PA polymers provided sufficient protection (ca. 84–88%) to bound DNA against nucleases and one of the formulations, Tmg‐PA2 (ca. 15% substitution) displayed the highest transfection efficiency outcompeting the commercial transfection reagent, Lipofectamine? with minimal cytotoxicity. More impressively, the transfection efficiency increased despite recording a decrease in the buffering capacity of the grafted polymers suggesting that buffering capacity is not the sole parameter in determining the gene delivery efficiency of a vector system. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Phase transfer synthesis of N,N′(1,2-phenylene)bis-hippuricamide tethered metal based functionalized nanoparticles: A study on some novel microbial targeting peptide-mimic nanoparticles

This paper presents the novel synthesis of peptide, N,N′(1,2-phenylene)bis-hippuricamide tethered metal [Cu(II), Zn(II), Ni(II) and Co(II)] based functionalized nanoparticles via modified Brust-Schiffrin methodology. The growth, organic composition and morphology of these functionalized nanoparticles have been evaluated by UV-Vis, FT-IR spectroscopy and scanning electron microscopy. They are structurally and thermally characterized by X-ray diffraction and thermogravimetric analysis. Moreover, the interfacial dealings of these functionalized nanoparticles with Calf-thymus DNA and pUC19 DNA reveal that the functionalized nanoparticles of cobalt is an effective DNA damaging agent under physiological conditions. This has been supported by its efficient antimicrobial character against few fungal and bacterial strains, thereby steering its way towards biomedical applications as a metal based nanocarrier.