Magneto-responsive nanocomposites: Preparation and integration of magnetic nanoparticles into films,capsules, and gels

This review reports on the latest developments in the field of magnetic nanocomposites, with a special focus on the potentials introduced by the incorporation of magnetic nanoparticles into polymer and supramolecular matrices. The general notions and the state of the art of nanocomposite materials are summarized and the results reported in the literature over the last decade on magnetically responsive films, capsules and gels are reviewed. The most promising concepts that have inspired the design of magneto-responsive nanocomposites are illustrated through remarkable examples where the integration of magnetic nanoparticles into organic architectures has successfully taken to the development of responsive multifunctional materials.     

Green synthesis and characterizations of Nickel oxide nanoparticles using leaf extract of Rhamnus virgata and their potential biological applications

In the present report, Nickel oxide nanoparticles (NiONPs) were synthesized using Rhamnus virgata (Roxb.) (Family: Rhamnaceae) as a potential stabilizing, reducing and chelating agent. The formation, morphology, structure and other physicochemical properties of resulting NiONPs were characterized by Ultra violet spectroscopy, X‐ray diffraction (XRD), Fourier Transform Infrared analysis (FTIR), Scanning electron microscopy (SEM), Energy‐dispersive‐spectroscopy (EDS), Transmission electron microscopy (TEM), Raman spectroscopy and dynamic light scattering (DLS). Detailed in vitro biological activities revealed significant therapeutic potential for NiONPs. The antimicrobial efficacy of biogenic NiONPs was demonstrated against five different gram positive and gram negative bacterial strains. Klebsiella pneumoniae and Pseudomonas aeruginosa (MIC: 125 μg/mL) were found to be the least susceptible and Bacillus subtilis (MIC: 31.25 μg/mL) was found to be the most susceptible strain to NiONPs. Biogenic NiONPs were reported to be highly potent against HepG2 cells (IC₅₀: 29.68 μg/ml). Moderate antileishmanial activity against Leishmania tropica (KMH₂₃) promastigotes (IC₅₀: 10.62 μg/ml) and amastigotes (IC₅₀: 27.58 μg/ml) cultures are reported. The cytotoxic activity was studied using brine shrimps and their IC₅₀ value was recorded as 43.73 μg/ml. For toxicological assessment, NiONPs were found compatible towards human RBCs (IC₅₀: > 200 μg/ml) and macrophages (IC₅₀: > 200 μg/ml), deeming particles safe for various applications in nanomedicines. Moderate antioxidant activities: total antioxidant capacity (TAC) (51.43%), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) activity (70.36%) and total reducing power (TRP) (45%) are reported for NiONPs. In addition, protein kinase and alpha amylase inhibition assays were also performed. Our results concluded that Rhamnus virgata synthesized NiONPs could find important biomedical applications with low cytotoxicity to normal cells.     

Overcoming the Inhibition Effects of Citrate: Precipitation of Ferromagnetic Magnetite Nanoparticles with Tunable Morphology,Magnetic Properties,and Surface Charge via Ferrous Citrate Oxidation

This study demonstrates how the method of thermally assisted oxidative precipitation in water can be opened for—the so far neglected—metal organic iron(II) complexes (herein: citrate) in order to obtain, in one step, ferromagnetic magnetite nanoparticles, possessing essential ligand properties. Based on a dedicated analysis of the specific precursor in combination with the consideration of known properties of the ligand, it is possible to identify existing inhibition-attributes of the iron organyl such that these can be overcome. Moreover, they can be exploited in a targeted manner; thus, simply by changing concentrations, a variety of magnetite nanoparticle morphologies with distinct properties can be obtained. In the case of the herein investigated ferrous citrate, three major inhibition effects are identified. While two of them efficiently prevent the formation of magnetite and need to be addressed to be overcome, the third can be exploited to selectively synthesize, for example, relatively stable carboxyl group-bearing nuclei clusters, exhibiting the properties of magnetically responsive photonic crystals, or relatively large mesocrystals, whose intraparticular magnetic interactions are apparently disturbed.     

The role of inorganic nanoparticle on ion conduction of epoxy-based solid polymer electrolytes for lithium-ion batteries

Abstract

Recently, extensive efforts have focused on the development of solid polymer electrolytes (SPEs) requiring high mechanical performance without sacrificing ion conductivity. To develop such a SPE, we incorporate robust silica mesoporous particles (SMP) into the epoxy-based SPEs, and increasing the SMP content raises the glass transition temperature of the SPEs. This enables to increase the mechanical properties of the SPEs, supported by the microstructural investigation showing a highly compact structure. Ionic conductivities of these SPEs follow Vogel temperature dependence, and increasing the silica nanoparticle content leads to a slight decrease in the conductivity, consistent with the dielectric response investigation.     

New Route of Microwave-Assisted Synthesis of Carbon-Supported Nickel Phosphide (C/Ni2P) Nanocomposite

Abstract

A novel, fast, and easy method for synthesizing a carbon-supported Ni₂P nanocomposite (C/Ni₂P) is described. The process involves a reaction between a nickel salt, phosphoric acid, and a carbon source by utilizing microwave irradiation. The carbon source for the nanocomposite is from renewable supplies, namely, tannin and lignin. The method has successfully synthesized Ni₂P nanoparticles dispersed in a carbon matrix with a particle size ranging from 20 to 50 nm in diameter. During the microwave process, tannin and lignin provided a reducing environment in the microwave irradiation process. The synthesized products are characterized by several characterization methods. The method showed that phosphoric acid, which is a nontoxic compound, could be used as an alternative P source for synthesizing Ni₂P. The method is fast, easy, and an economical process to synthesize the carbon-coated Ni₂P nanocomposite.     

Rare-earth Doped Nanoparticles with Narrow NIR-II Emission for Optical Imaging with Reduced Autofluorescence

Fluorescence imaging in the second near-infrared region(900-1700 nm, NIR-II) with a high resolution and penetration depth due to the significantly reduced tissue scattering and autofluorescence has emerged as a useful tool in biomedical fields. Recently, many efforts have been devoted to the development of fluorophores with an emission band covering the long-wavelength end of NIR-II region(1500-1700 nm) to eliminate the autofluorescence. Alternatively, we believe imaging with a narrow bandwidth could also reduce the autofluorescence. As a proof of concept, NaYF₄:Yb,Nd@NaYF₄ downconversion nanoparticles(DCNPs) with sharp NIR-II emission were synthesized. The luminescence of DCNPs showed a half-peak width of 49 nm centered at 998 nm, which was perfectly matched with a (1000±25) nm bandpass filter. With this filter, we were able to retain most of the emissions from the nanoparticles, while the autofluorescence was largely reduced. After PEGylation, the DCNPs exhibited great performance for blood vessel and tumor imaging in living mice with significantly reduced autofluorescence and interference signals. This work provided an alternative way for the low-autofluorescence imaging and emphasized the importance of narrow emitting rare-earth doped nanoparticles for NIR-II imaging.     

Cooperative Dehydrogenation of N‐Heterocycles Using a Carbon Nanotube–Rhodium Nanohybrid

Rhodium nanoparticles were anchored on carbon nanotubes and the resulting nanohybrid was studied as co‐catalyst, along with tert‐butylcatechol, for the dehydrogenation of various N‐heterocycles. The co‐catalytic system operates in high yields, under the mildest conditions reported so far, and can be applied to a wide variety of secondary amine‐containing scaffolds.     

Magnetic nanoparticle‐tethered Schiff base–palladium(II): Highly active and reusable heterogeneous catalyst for Suzuki–Miyaura cross‐coupling and reduction of nitroarenes in aqueous medium at room temperature

As a continuation of our efforts to develop new heterogeneous nanomagnetic catalysts for greener reactions, we identified a Schiff base–palladium(II) complex anchored on magnetic nanoparticles (SB‐Pd@MNPs) as a highly active nanomagnetic catalyst for Suzuki–Miyaura cross‐coupling reactions between phenylboronic acid and aryl halides and for the reduction of nitroarenes using sodium borohydride in an aqueous medium at room temperature. The SB‐Pd@MNPs nanomagnetic catalyst shows notable advantages such as simplicity of operation, excellent yields, short reaction times, heterogeneous nature, easy magnetic work up and recyclability. Characterization of the synthesized SB‐Pd@MNPs nanomagnetic catalyst was performed with various physicochemical methods such as attenuated total reflectance infrared spectroscopy, UV–visible spectroscopy, inductively coupled plasma atomic emission spectroscopy, energy‐dispersive X‐ray spectroscopy, field‐emission scanning electron microscopy, transmission electron microscopy, powder X‐ray powder diffraction, thermogravimetric analysis and Brunauer–Emmett–Teller surface area analysis.