Structural characterization of self-assembled chain like Fe-FeOx Core shell nanostructure

Mössbauer spectroscopic investigations on iron oxides and modified nanostructures: A review

Pure and doped iron oxide and hydroxide nanoparticles are highly potential materials for biological, environment, energy and other technological applications. On demand of the applications, single phase as well as multiple phase of different polymorphs or composites of iron oxides with compatible materials for example, zeolite, SiO₂, or Au are prepared. The properties of the as-synthesized nanoparticles are predominantly dictated by the local structure and the distribution of the cations. Mössbauer spectroscopy is a perfect and efficient characterization technique to investigate the local structure of the Mössbauer-active element such as Fe, Au, and Sn. In the present review, the local structure transformation on the optimization of the magnetite coexisted with iron hydroxides, spin dynamics of the bare, caped, core-shell and the composites of iron oxide nanoparticles (IONPs), dipole-dipole interactions and the diffusion of IONPs were discussed, based on the findings using Mössbauer spectroscopy.

L-cysteine embedded core-shell ZnO microspheres composed of nanoclusters enhances anticancer activity against liver and breast cancer cells

Nano-based products have become an apparent and effective option to treat liver cancer, which is a deadly disease, and minimize or eradicate these problems. The Core-shell ZnO microspheres composed of nanoclusters (ZnOMS-NCs) have shown that it is very worthwhile to administer the proliferation rate in HepG2 and MCF-7 cancer cells even at a very low concentration (5 μg/mL). ZnOMS-NCs were prepared through hydrothermal solution process and well characterized. The MTT assay revealed that the cytotoxic effects were dose-dependent (2.5 μg/mL-100 μg/mL) on ZnOMS-NCs. The diminished activity in cell viability induces the cytotoxicity response to the ZnOMS-NCs treatment of human cultured cells. The qPCR data showed that the cells (HepG2 and MCF-7) were exposed to ZnOMS-NCs and exhibited up-and downregulated mRNA expression of apoptotic and anti-apoptotic genes, respectively. In conclusion, flow cytometric data exhibited significant apoptosis induction in both cancer cell lines at low concentrations. The possible mechanism also describes the role of ZnOMS-NCs against cancer cells and their responses.

Strong influence of degree of substitution on carboxymethyl cellulose stabilized sulfidated nanoscale zero-valent iron

Carboxymethyl cellulose (CMC) has been widely adopted as stabilizer to enhance the subsurface mobility of nanoscale zerovalent iron (nZVI). However, CMC surface modification also cause severe decrease of the longevity and electron utilization efficiency (ε_e) of nZVI, which is still not well understood. In this study, we demonstrate the negative influence of CMC on the properties of sulfidated nZVI (S-nZVI) could be reversed by increasing the degree of substitution (D.S.) of CMC. Consistent with previous study, the sample CMC-S-nZVI prepared with commercial CMC with degree of substitution (D.S.) of 0.75 exhibited a considerable low longevity of 33 days with ε_e of 4.5%, much lower than that of sulfidated nZVI (S-nZVI, 113 days and 13%). In sharp contrast, the sample HCMC-S-nZVI synthesized with CMC with super high D.S. of 1.76 demonstrated significantly enhanced longevity of 139 days and ε_e of 20%. The enhancement was attributed to compatible molecular structure of CMC with super high D.S. Moreover, the HCMC-S-nZVI also exhibited higher mobility in porous media than CMC-S-nZVI. Our work provides a feasible way to prepare S-nZVI with desired properties including high subsurface transportability, high longevity and high ε_e.

From Microenvironment Remediation to Novel Anti-Cancer Strategy: The Emergence of Zero Valent Iron Nanoparticles

Accumulated studies indicate that zero-valent iron (ZVI) nanoparticles demonstrate endogenous cancer-selective cytotoxicity, without any external electric field, lights, or energy, while sparing healthy non-cancerous cells in vitro and in vivo. The anti-cancer activity of ZVI-based nanoparticles was anti-proportional to the oxidative status of the materials, which indicates that the elemental iron is crucial for the observed cancer selectivity. In this thematic article, distinctive endogenous anti-cancer mechanisms of ZVI-related nanomaterials at the cellular and molecular levels are reviewed, including the related gene modulating profile in vitro and in vivo. From a material science perspective, the underlying mechanisms are also analyzed. In summary, ZVI-based nanomaterials demonstrated prominent potential in precision medicine to modulate both programmed cell death of cancer cells, as well as the tumor microenvironment. We believe that this will inspire advanced anti-cancer therapy in the future.

Magnetic nanowires in biomedical applications

Magnetic nanostructures and nanomaterials play essential roles in modern bio medicine and technology. Proper surface functionalization of nanoparticles (NPs) allows the selective bonding thus application of magnetic forces to a vast range of cellular structures and biomolecules. However, the spherical geometry of NPs poises a series of limitations in various potential applications. Mostly, typical spherical core shell structure consists of magnetic and non-magnetic layers have little tunability in terms of magnetic responses, and their single surface functionality also limits chemical activity and selectivity. In comparison to spherical NPs, nanowires (NWs) possess more degrees of freedom in achieving magnetic and surface chemical tenability. In addition to adjustment of magnetic anisotropy and inter-layer interactions, another important feature of NWs is their ability to combine different components along their length, which can result in diverse bio-magnetic applications. Magnetic NWs have become the candidate material for biomedical applications owing to their high magnetization, cheapness and cost effective synthesis. With large magnetic moment, anisotropy, biocompatibility and low toxicity, magnetic NWs have been recently used in living cell manipulation, magnetic cell separation and magnetic hyperthermia. In this review, the basic concepts of magnetic characteristics of nanoscale objects and the influences of aspect ratio, composition and diameter on magnetic properties of NWs are addressed. Some underpinning physical principles of magnetic hyperthermia (MH), magnetic resonance imaging (MRI) and magnetic separation (MS) have been discussed. Finally, recent studies on magnetic NWs for the applications in MH, MRI and MS were discussed in detail.

Plasma-assisted electrochemical synthesis of monodisperse Au and Au@Ag core-shell nanoparticles

The synthesis of well defined nanoparticles with green chemistry has been an area of intense investigation, but still requires development. In this study, we propose a novel approach for controlling the particle size and distribution through diffusion-controlled growth of plasma-assisted electrochemical synthesis. The continuous, controlled addition of an Au precursor with syringe pump successfully controls the particle size in the range of 50-300 nm with a monodisperse size distribution. Moreover, gold nanoparticles can be formed successfully without any stabilizer and reducing agent. Through optimization of the reaction parameters, including the reaction temperature, discharge current of the microplasma, pH, and concentration of D-(-)-fructose, we verify two distinct feature of diffusion-controlled growth that the particle growth is good agreement of theoretical growth rate (r ∼ t ^1/3) and the formed gold nanoparticles exhibit polyhedral or near-spherical shapes. This method has been applied to synthesize Au@Ag core-shell nanoparticles and control the Ag shell thickness.

Catalytic Activity of Hybrid Iron Oxide Silver Nanoparticles in Methyl Methacrylate Polymerization

One of the challenges in the preparation of poly(methyl methacrylate) (PMMA) is to develop new catalytic systems with improved efficiency. A hybrid iron oxide silver catalyst holds promise in solving this issue. Catalysts were prepared at room temperature by a two-step technique. First, iron oxide nanoparticles were prepared by the reduction of FeCl3 using sodium borohydride (NaBH4) at room temperature. Second, magnetic nanoparticles doped with a series of Ag nanoparticles (Ag, Ag/3 –amino propyltriethoxysilane (APTES) and Ag/poly(ethyleneimine) (PEI)). The prepared catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), and Fourier-transform infrared spectroscopy (FTIR). The catalytic activity of Fe, Ag/Fe, PEI–Ag/Fe, and APTES–Ag/Fe in methyl methacrylate (MMA) polymerization was investigated in the presence of O2, N2, NaHSO3, and benzoyl peroxide in bulk or solution conditions. The produced polymer was characterized by gel permeation chromatography (GPC) and proton nuclear magnetic resonance spectroscopy (1HNMR). The structures of PEI–Ag/Fe and APTES–Ag/Fe are assumed. The conversion efficiency was 100%, 100%, 97.6%, and 99.1% using Fe, Ag/Fe, PEI–Ag/Fe, and APTES–Ag/Fe catalysts at the optimum conditions, respectively. Hybrid iron oxide silver nanoparticles are promising catalysts for PMMA preparation.

Multi-Segmented Nanowires: A High Tech Bright Future

In the last couple of decades, there has been a lot of progress in the synthesis methods of nano-structural materials, but still the field has a large number of puzzles to solve. Metal nanowires (NWs) and their alloys represent a sub category of the 1-D nano-materials and there is a large effort to study the microstructural, physical and chemical properties to use them for further industrial applications. Due to technical limitations of single component NWs, the hetero-structured materials gained attention recently. Among them, multi-segmented NWs are more diverse in applications, consisting of two or more segments that can perform multiple function at a time, which confer their unique properties. Recent advancement in characterization techniques has opened up new opportunities for understanding the physical properties of multi-segmented structures of 1-D nanomaterials. Since the multi-segmented NWs needs a reliable response from an external filed, numerous studies have been done on the synthesis of multi-segmented NWs to precisely control the physical properties of multi-segmented NWs. This paper highlights the electrochemical synthesis and physical properties of multi-segmented NWs, with a focus on the mechanical and magnetic properties by explaining the shape, microstructure, and composition of NWs.