Magnetic Core Shell Nanocomposites Research Articles

Effective Role of Magnetic Core-Shell Nanocomposites in Removing Organic and Inorganic Wastes from Water

Effective Role of Magnetic Core-Shell Nanocomposites in Removing Organic and Inorganic Wastes from Water

Synthesis and Characterization of Doxorubicin Loaded pH-Sensitive Magnetic Core–Shell Nanocomposites for Targeted Drug Delivery Applications

In order to improve the effects of medical therapy for cancer, we prepared magnetic nanocomposites (Fe3O4@SiO2–NH–NH[Formula: see text] as doxorubicin (DOX) carriers via two different schemes. Scheme (I): the carriers were synthesized from magnetic silica nanoparticles (Fe3O4@SiO[Formula: see text] via layer by layer modification, scheme (II): the carriers were obtained from amino-modified magnetic silica nanoparticles (Fe3O4@SiO2–NH[Formula: see text] synthesized by one-step, and followed by surface modification. In order to load DOX effectively, the surface of the carriers were further modified to make the surface with a large number of hydrazine bonds which can form a pH-sensitive bond (hydrazone bond) with DOX. The two kinds of carriers both exhibited a size around 80[Formula: see text]nm, high stability and superparamagnetic behavior. However, DOX-loaded carriers (Fe3O4@SiO2–DOX(2)) performed relatively poorer performance in terms of drug loading and releasing (the loading efficiency of DOX decreased from 67.33% to 42.15%, while the releasing efficiency of DOX decreased from 66.16% to 62.23% within 72[Formula: see text]h at pH 4.0). Water-soluble tetrazolium salts (WST-1) assays in cancer cells (Hela) demonstrated that the Fe3O4@SiO2–DOX presented high anti-tumor activity, while the carriers were nearly nontoxic. Thus, the results suggested that the magnetic nanocomposites synthesized by the two different methods both can be employed to deliver DOX, while the carriers obtained via the first method may perform better and would be applied in the field of cancer therapy in the future.

Preparation of a four-layer magnetic core–shell nanocomposite for the selective hydrogenation of cinnamic acid

A novel magnetic mesoporous four-layer core–shell nanocomposite Fe3O4@nSiO2@ZrO2@Ni–Co–B was successfully fabricated by the combination of a modified Stober sol–gel and self-assemble method. A facile template-free approach was employed to introduce the zirconia shell, which was more efficient than the conventional surfactant-templating method for the introduction of the mesoporous silica shell. This nanocomposite was composed of a ferroferric oxide core, an inner dense silica shell and a mesoporous zirconia shell in sequence and an outer Ni–Co–B amorphous alloy shell, as demonstrated by transmission electron microscope, X-ray energy dispersive spectroscopy, and nitrogen adsorption–desorption. It exhibited excellent catalytic performance in the selective hydrogenation of cinnamic acid to hydrocinnamic acid with almost 100 % yield. Additionally, it can be easily separated from the reaction mixture by using an external magnetic field due to its proper magnetic property and recycled effectively for five consecutive runs, making it an attractive candidate in efficient hydrogenations.

Efficient sorption of Pb(ii) from an aqueous solution using a poly(aniline-co-3-aminobenzoic acid)-based magnetic core–shell nanocomposite

We propose that the PA3ABA@Fe3O4 core–shell magnetic nanocomposite is an appropriate candidate for water treatment processes.

Biocompatible magnetic core-shell nanocomposites for engineered magnetic tissues.

The inclusion of magnetic nanoparticles into biopolymer matrixes enables the preparation of magnetic field-responsive engineered tissues. Here we describe a synthetic route to prepare biocompatible core-shell nanostructures consisting of a polymeric core and a magnetic shell, which are used for this purpose. We show that using a core-shell architecture is doubly advantageous. First, gravitational settling for core-shell nanocomposites is slower because of the reduction of the composite average density connected to the light polymer core. Second, the magnetic response of core-shell nanocomposites can be tuned by changing the thickness of the magnetic layer. The incorporation of the composites into biopolymer hydrogels containing cells results in magnetic field-responsive engineered tissues whose mechanical properties can be controlled by external magnetic forces. Indeed, we obtain a significant increase of the viscoelastic moduli of the engineered tissues when exposed to an external magnetic field. Because the composites are functionalized with polyethylene glycol, the prepared bio-artificial tissue-like constructs also display excellent ex vivo cell viability and proliferation. When implanted in vivo, the engineered tissues show good biocompatibility and outstanding interaction with the host tissue. Actually, they only cause a localized transitory inflammatory reaction at the implantation site, without any effect on other organs. Altogether, our results suggest that the inclusion of magnetic core-shell nanocomposites into biomaterials would enable tissue engineering of artificial substitutes whose mechanical properties could be tuned to match those of the potential target tissue. In a wider perspective, the good biocompatibility and magnetic behavior of the composites could be beneficial for many other applications.

Supported polymer magnets with high catalytic performance in the green reduction of nitroaromatic compounds

We exhibit the synthesis of magnetic core–shell nanocomposites as solid phase catalysts in the reduction of nitroaromatics.

In-situ assembly of biocompatible core–shell hierarchical nanostructures sensitized immunosensor for microcystin-LR detection

Microcystin-LR (MC-LR) is a kind of hepatotoxin which can cause functional and structural disturbances of the liver, accumulate in aquatic organisms and transfer to higher trophic levels, a biocompatible electrochemical immunosensor was constructed to detect MC-LR sensitively and selectively. The three-dimensional villiform-like carbon nanotube/cobalt silicate (CNT@Co silicate) core–shell nanocomposites were synthesized and firstly used as the substrate to immobilize the antigen of MC-LR (Ag), while Fe3O4 nanoclusters/polydopamine/gold nanoparticles (Fe3O4@PDA–Au) core–shell magnetic nanocomposites were prepared as the label carrier of the immunosensor to conjugate the second antibody (Ab2) and horse radish peroxidase (HRP). Since the toxicity of nanomaterials is important in the construction of biosensors including the immobilization of antigen or antibody, the biocompatibility of such nanocomposites were investigated by monitoring the cell viability after culturing with Hela cells. Due to the excellent biocompatibility, the immunosensor can immobilize more antigens by the large surface area of the three-dimensional villiform-like structure in CNT@Co silicate, and provide high electrochemical signals by Fe3O4@PDA–Au labeled Ab2 and HRP. After investigation of the binding capability of biomolecules on nanomaterials and optimization of the conditions in the competitive immunoassay, the proposed electrochemical immunosensor shows a linear response to MC-LR in the range from 0.005μg/L to 50μg/L with a detection limit of 0.004μg/L. In addition, the specificity, reproducibility and stability of the immunosensor were also proved to be acceptable, indicating its potential application in environmental monitoring.

Enzyme-sensitive magnetic core–shell nanocomposites for triggered drug release

Sodium hyaluronic acid cross-linked gel was employed to coat outside of Fe3O4@mSiO2 nanopaticles to prevent drug pervasion by a novel approach.

Facile synthesis of magnetic core-shell nanocomposites for MRI and CT bimodal imaging.

With the development of nanotechnology, nanocomposites have been used as bimodal contrast agents for magnetic resonance (MR) and computed tomography (CT) imaging. We have developed a facile method for the synthesis of iron oxide@bismuth sulfide magnetic core-shell nanocomposites. These bifunctional nanocomposites can be made water-soluble via PEG coating and present strong MRI/CT contrast enhancement. Evaluation of cytotoxicity by MTT assay shows that the nanocomposites have low cytotoxicity. The results illustrate that the nanocomposites have great potential as bimodal imaging agents for MR/CT.

Rhodamine functionalized magnetic core–shell nanocomposite: An emission “Off–On” sensing system for mercury ion detection and extraction

This paper reported a core–shell structured composite with superparamagnetic ferroferric oxide as the inner core and silica molecular sieve as the outer shell. A rhodamine based sensing dye was covalently grafted into the highly ordered tunnels of silica molecular sieve, so that mercury ion sensing and extraction could be achieved from this composite. This probe loaded core–shell structure was characterized by electron microscopy images, X-ray diffraction patterns, infrared spectra, thermogravimetry and N2 adsorption/desorption measurement. This composite showed increased emission with increasing mercury ion concentration, along with high sensitivity and good selectivity. Linear response and good regenerating performance were also observed from this composite.

ChemInform Abstract: An Ammonium Molybdate Deposited Amorphous Silica Coated Iron Oxide Magnetic Core—Shell Nanocomposite for the Efficient Synthesis of 2‐Benzimidazoles Using Hydrogen Peroxide.

An ammonium molybdate deposited amorphous silica coated iron oxide (Fe3O4@SiO2) magnetic core–shell nanocomposite was prepared and tested in the application to the synthesis of 2-benzimidazoles from aromatic aldehydes and o-phenylenediamines using hydrogen peroxide as an oxidant at room temperature. It was found that the yields were fundamentally influenced by the nature and position of the substituents on the phenyl ring. Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) confirmed that the active ammonium molybdate species are highly dispersed on the surface of the Fe3O4@SiO2 magnetic core–shell nanocomposite, accounting for its good activity. A method was eventually developed for the synthesis of 2-benzimidazoles highlighting the good activity and easily recyclable nature of this magnetic catalyst.

Dendrimer grafted core–shell Fe3O4–polymer magnetic nanocomposites stabilized with AuNPs for enhanced catalytic degradation of Rhodamine B – A kinetic study

In this paper, three types of novel magnetically recoverable core–shell heterogeneous nanoparticle catalysts were prepared by individual grafting of poly(amidoamine) dendrimer with generation G(0), G(1) and G(2) on Fe3O4–Poly(4-MS-DVB-GMA) core–shell as a common matrix followed by stabilization of AuNPs. The SPR peak noticed at 547 nm in UV confirms the formation of AuNPs in each catalyst. The SEM supports the construction of core–shell magnetic nanocomposite in which an interior layer due to Fe3O4 core and the outer thick layer due to Poly(4-MS-DVB-GMA) shell grafted with PAMAM-G(0), G(1) and G(2) dendrimers and the XRD shows core size of Fe3O4 is 8 nm. From VSM analysis, the quantum of Fe3O4 NPs is estimated as 95.5%, 82.2%, 50.2%, 15.1% in OA-Fe3O4 and core–shelled Fe3O4–Poly(4-MS-DVB-GMA)–PAMAM-G(0), G(1) and G(2)-AuNPs. The XPS shows the presence of C(1s), N(1s), O(1s), Fe(2p) and Au(4f) elements. The reduction of Rhodamine B reveals that Fe3O4–Poly(4-MS-DVB-GMA)–PAMAM-G(2) is 6 times (kobs = 35.28 × 10−3 min−1) active than the G(0) dendrimer catalyst and its activity is maintained upto 5th cycle thus enlightening the recyclability and stability.

PH-responsive magnetic core-shell nanocomposites for drug delivery.

Polymer-modified nanoparticles, which can load anticancer drugs such as doxorubicin (DOX), showing the release in response to a specific trigger, have been paid much attention in cancer therapy. In our study, a pH-sensitive drug-delivery system consisting of Fe3O4@mSiO2 core-shell nanocomposite (about 65 nm) and a β-thiopropionate-poly(ethylene glycol) "gatekeeper" (P2) has been successfully synthesized as a drug carrier (Fe3O4@mSiO2@P2). Because of the hydrolysis of the β-thiopropionate linker under mildly acidic conditions, Fe3O4@mSiO2@P2 shows a pH-sensitive release performance based on the slight difference between a tumor (weakly acid) and normal tissue (weakly alkaline). And before reaching the tumor site, the drug-delivery system shows good drug retention. Notably, the nanocomposites are quickly taken up by HeLa cells due to their small particle size and the poly(ethylene glycol) modification, which is significant for increasing the drug efficiency as well as the cancer therapy of the drug vehicles. The excellent biocompatibility and selective release performance of the nanocomposites combined with the magnetic targeted ability are expected to be promising in the potential application of cancer treatment.

Hydrazide functionalized core-shell magnetic nanocomposites for highly specific enrichment of N-glycopeptides.

In view of the biological significance of glycosylation for human health, profiling of glycoproteome from complex biological samples is highly inclined toward the discovery of disease biomarkers and clinical diagnosis. Nevertheless, because of the existence of glycopeptides at relatively low abundances compared with nonglycosylated peptides and glycan microheterogeneity, glycopeptides need to be highly selectively enriched from complex biological samples for mass spectrometry analysis. Herein, a new type of hydrazide functionalized core-shell magnetic nanocomposite has been synthesized for highly specific enrichment of N-glycopeptides. The nanocomposites with both the magnetic core and the polymer shell hanging high density of hydrazide groups were prepared by first functionalization of the magnetic core with polymethacrylic acid by reflux precipitation polymerization to obtain the Fe3O4@poly(methacrylic acid) (Fe3O4@PMAA) and then modification of the surface of Fe3O4@PMAA with adipic acid dihydrazide (ADH) to obtain Fe3O4@poly(methacrylic hydrazide) (Fe3O4@PMAH). The abundant hydrazide groups toward highly specific enrichment of glycopeptides and the magnetic core make it suitable for large-scale, high-throughput, and automated sample processing. In addition, the hydrophilic polymer surface can provide low nonspecific adsorption of other peptides. Compared to commercially available hydrazide resin, Fe3O4@PMAH improved more than 5 times the signal-to-noise ratio of standard glycopeptides. Finally, this nanocomposite was applied in the profiling of N-glycoproteome from the colorectal cancer patient serum. In total, 175 unique glycopeptides and 181 glycosylation sites corresponding to 63 unique glycoproteins were identified in three repeated experiments, with the specificities of the enriched glycopeptides and corresponding glycoproteins of 69.6% and 80.9%, respectively. Because of all these attractive features, we believe that this novel hydrazide functionalized core-shell magnetic nanocomposite will shed new light on the profiling of N-glycoproteome from complex biological samples in high throughput.

An ammonium molybdate deposited amorphous silica coated iron oxide magnetic core–shell nanocomposite for the efficient synthesis of 2-benzimidazoles using hydrogen peroxide

An eco-friendly method was developed for the synthesis of 2-benzimidazoles over an Fe3O4@SiO2@(NH4)6Mo7O24 magnetic core–shell nanocomposite using hydrogen peroxide.

Magnetic iron oxide nanoparticles coated by hierarchically structured silica: a highly stable nanocomposite system and ideal catalyst support

A well-defined core–shell nanocomposite with magnetic iron oxide nanoparticles coated by a hierarchically structured silica shell has been synthesized through a sol–gel process and pseudomorphic transformation. The prepared materials were characterized by means of transmission electron microscopy, small and wide angle X-ray diffraction, Mossbauer spectroscopy and N2 physical adsorption–desorption. It has been shown that the core–shell nanocomposite possesses a magnetic core in the form of Fe3O4 or γ-Fe2O3 and a unique hierarchically structured silica shell consisting of an inner nonporous shell and outer shell with hierarchical pores. As a result, this nanocomposite exhibits high stability (acid resistance) and a large surface area (447 m2 g−1), which will be especially suitable for use as catalyst supports. To demonstrate this point, a functional catalyst consisting of small Pt nanoparticles well-dispersed on the porous surface of the magnetic core–shell nanocomposite was fabricated. In the hydrogenation of nitrobenzene and 2-nitrochlorobenzene to the corresponding aniline compounds, the hierarchically porous catalyst showed superior performances to its counterpart with a monomodal porous structure. In addition, the used catalyst could be separated conveniently from the reaction system with an external magnetic field. Subsequent recycling tests further confirmed the outstanding reusability and regeneration ability of the composite catalyst.

Porous TiO2-coated Magnetic Core-Shell Nanocomposites: Preparation and Enhanced Photocatalytic Activity

The core-shell structured TiO2/SiO2@Fe3O4 photocatalysts were prepared using Fe3O4 as magnetic core, tetraethoxysilane (TEOS) as silica source and tetrabutyl titanate (TBOT) as titanium sources. The as-obtained structure was composed of a SiO2@Fe3O4 core and a porous TiO2 shell. The diameter of SiO2@Fe3O4 core was about 205 nm with thickness of porous TiO2 of about 5-6 nm. The 9%TiO2/6% SiO2@Fe3O4 microspheres possess the highest BET surface area and the BJH pore volume, which are 373.5 m2·g−1 and 0.28 cm3·g−1, respectively. The 9%TiO2/6%SiO2@Fe3O4 photocatalyst exhibited an excellent performance for the degradation of methyl orange and methylene blue dyes. Two different dyes were completely decolorized in 60 min under UV irradiation. The photocatalytic activity and the amount of catalyst were almost not decrease after recycling for 6 times by using external magnetic field.

Preparation of a novel Fe3O4@SiO2@Ni–La–B magnetic core–shell nanocomposite for catalytic hydrogenation

A novel Fe3O4@SiO2@Ni–La–B magnetic core–shell nanocomposite was prepared by a combination of the Stöber method and self-assembly. In this process, Fe3O4 nanoparticles were first coated with amorphous silica, forming Fe3O4@SiO2 core–shell structural nanocomposites. Ni2+ and La3+ were then loaded onto the surface of Fe3O4@SiO2, followed by reduction with KBH4 to assemble a layer of Ni–La–B onto the surface of Fe3O4@SiO2. The obtained Fe3O4@SiO2@Ni–La–B core–shell nanocomposite has high saturation magnetization (20.6emu/g), compared to that of Ni–La–B (only 0.4emu/g). This magnetic core–shell nanocomposite showed high activity and good selectivity in the catalytic hydrogenation of benzophenone to benzhydrol, and can be easily separated and recycled after reaction.

Fabrication of magnetic core–shell nanocomposites with superior performance for water treatment

Magnetic core–shell nanocomposites were synthesized by an economical and environmentally friendly method. The shell materials with the desired composition can be obtained through simple manipulation of precursor adsorption, which can modify their performance for water treatment. The composite containing appropriate amounts of Fe, Mn, and Co oxides exhibits excellent adsorption capability and catalytic activity for removing heavy metal ions and organic pollutants in water. The results suggest that the chemical modification of the shell material is promising for the optimization of pollutants removal by core–shell nanocomposites.

Facile synthesis of a Ni(ii)-immobilized core-shell magnetic nanocomposite as an efficient affinity adsorbent for the depletion of abundant proteins from bovine blood.

In this study, a facile and efficient separation of abundant proteins from bovine blood using core-shell structure nanoparticles with a magnetic core and an immobilized metal affinity ligand iminodiacetic acid (IDA) chelating Ni(ii) is presented. Firstly, Fe3O4 magnetic nanoparticles (MNPs) were synthesized through a solvothermal method and then were conveniently surface-modified with 3-(methacryloyloxy) propyltrimethoxylsilane as anchor molecules to donate vinyl groups. Next a high density poly(4-vinylbenzylchloride) (PVBC) shell was synthesized on the surface of silica-coated Fe3O4 MNPs via distillation-precipitation polymerization. After the PVBC shell reacted with iminodiacetic acid (IDA) in alkaline aqueous solution, the magnetite was charged with Ni2+ to form Ni(ii)-IDA functionalized hybrid Fe3O4@PVBC@IDA-Ni MNPs. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and a vibrating sample magnetometer (VSM) were employed to evaluate the size, morphology and magnetic property of the resulting magnetic nanospheres. The high saturation magnetization (48.1 emu g-1) provides the materials with the convenience of magnetic separation under an external magnetic field and they can be subsequently reused. The core-shell Fe3O4@PVBC@IDA-Ni MNPs exhibit excellent performance in the separation of protein bovine hemoglobin (BHb), and the binding capacity is as high as 1988 mg g-1. In addition, the Fe3O4@PVBC@IDA-Ni MNPs can be used in selective removal of abundant protein Hb in the bovine blood samples. This opens a novel route for its future application in removing abundant protein in proteomic analysis.