Shell Nanocomposites Research Articles

A magnetically recoverable photocatalyst prepared by supporting TiO2nanoparticles on a superparamagnetic iron oxide nanocluster core@fibrous silica shell nanocomposite

A magnetically recoverable photocatalyst was prepared by supporting TiO2nanoparticles on a superparamagnetic iron oxide nanocluster core@fibrous silica shell nanocomposite.

In situ SERS study of surface plasmon resonance enhanced photocatalytic reactions using bifunctional Au@CdS core-shell nanocomposites.

Surface plasmon resonance (SPR) has been utilized in many fields, such as surface-enhanced Raman spectroscopy (SERS) and solar energy conversion. Here we developed an Au@CdS core-shell nanostructure, a bifunctional nanoparticle, used as an efficient catalyst for SPR enhanced photocatalytic degradation, and as a substrate for in situ SERS detection of methylene blue (MB) and p-nitrophenol (pNTP). With integration of an Au nanoparticle into a CdS shell, the degradation process was significantly accelerated under 500 nm long-pass (λ > 500 nm) visible light irradiation, which was caused by the injection of hot electrons. Moreover, a highly uniform, monolayer film of Au@CdS nanoparticles (NPs) has been prepared and used as both a SERS substrate and catalyst. The decomposition of MB molecules and nitrogen coupling reaction of pNTP were observed during the 638 nm laser illumination. We demonstrate that a plasmonic core-semiconductor shell nanocomposite can be a promising material for photocatalysis and in situ SERS study.

Tunable Ag@SiO2 core–shell nanocomposites for broad spectrum antibacterial applications

Silica encapsulated silver nanoparticle core–shell nanocomposites of tunable dimensions were synthesised via a one-pot reverse microemulsion route to achieve controlled release of Ag+ ions for broad spectrum antibacterial application.

Preparation and Characterization of Folate-Targeted Fe3O4 Nanoparticle Codelivering Cisplatin and TFPI-2 Plasmid DNA for Nasopharyngeal Carcinoma Therapy

A novel folate (FA) receptor-targeted superparamagnetic Fe3O4 nanoparticles (SPIONs) codelivering cisplatin (CDDP) and tissue factor pathway inhibitor-2 (TFPI-2) plasmid DNA (pDNA) was constructed. The core shell nanocomposites (FA-PEG-PEI@SPION-CDDP-TFPI-2) were composed of superparamagnetic Fe3O4 core that binds CDDP and TFPI-2 shell that combines with folate-polyethylene glycol-polyethyleneimine (FA-PEG-PEI) via electrostatic interaction. The shell containing FA-PEG-PEI and TFPI-2 plasmid was synthesized through amidation reaction and electrostatic adsorption and the core containing SPION-CDDP was modified by aldehyde sodium alginate. Proton nuclear magnetic resonance and Fourier transform infrared spectra on FA-PEG-PEI polymers showed characteristic peaks of various metabolites in corresponding frequency. Transmission electron microscopy image of FA-PEG-PEI@SPION-CDDP-TFPI-2 nanoparticles demonstrated a near-monodisperse spherical morphology, while dynamic light scattering studies indicated an intensity-average diameter of 149.5 nm. Zeta potential was 14.89 ± 1.83 mv and the final concentration of loaded CDDP was 100 ug/ml. Gel electrophoresis data showed that the nanocomposite would protect TFPI-2 pDNA from being digested by DNases. Compared with CNE-2 cells, the good targetability and better gene transfection efficiency (57.9%) were detected by Prussian blue iron stain and fluorescence analysis in HNE-1 cells in vitro. The results suggested the potential application of FA-PEG-PEI@SPION-CDDP-TFPI-2 as a multifunctional anticancer nanomedicine on targeting therapy for FR positive NPC.

A novel methodology for fabrication of Ag–polypyrrole core–shell nanosphere using microemulsion system and evaluation of its antibacterial application

A novel methodology based on microemulsion system was used to prepare Ag–PPy core–shell nanocomposite for antibacterial application

Black TiO2 based core-shell nanocomposites as doxorubicin carriers for thermal imaging guided synergistic therapy of breast cancer.

TiO2 nanomaterials have been widely used for anticancer drug carriers and UV/980 nm NIR triggered cancer synergistic platforms. However, traditional pure TiO2 nanocarriers encounter some serious drawbacks, such as low drug loading ability, limited tissue penetration of UV light, and heating effect of 980 nm NIR on normal tissue, which obstruct their further application in cancer treatment. To overcome those challenges, novel mesoporous silica (mSiO2) coated black TiO2 core-shell nanocomposites are designed and constructed as doxorubicin carriers for 808 nm NIR triggered thermal imaging guided photothermal therapy combined chemotherapy of breast cancer. Properties of the nanocomposites such as micro-morphology, size, drug loading ability and release, targeting performance, and therapy efficiency in vitro and in vivo were evaluated. The results indicated the core-shell nanocomposites with dramatically increased loading ability were pH-responsive/NIR-accelerated doxorubicin release nanocarriers and showed synergistic breast cancer treatment in vitro and in vivo. This study verifies that the newly prepared mSiO2 coated black TiO2 core-shell nanocarriers can overcome the limitations of traditional TiO2 nanocarriers and thus improve and broaden usage of TiO2 nanoparticles in nanomedicine.

Carborane-layered double hydroxide nanohybrids for potential targeted- and magnetically targeted-BNCT applications.

Carborane-intercalated layered double hydroxide nanohybrids (CB-LDH) and a magnesium ferrite (MF) supported-CB-LDH core-shell nanocomposite (CB-LDH@MF) are reported. The preparation of nanohybrids were carried out by exchanging the interlayer nitrate groups of Mg-Al-NO3-LDH with monothiol-o-carborane (SCB), 1-methyl-2-carboxyl-o-carborane (MeCB), 1-phenyl-2-carboxyl-o-carborane (PhCB) and 1,12-dicarboxyl-p-carborane (COOHCB) molecules. A magnetic core-shell nanocomposite was further prepared by supporting the COOHCB-LDH nanohybrid on MF nanoparticles. The obtained materials were characterized by means of several physical and chemical methods. Chemical compositions were determined by elemental analysis, ICP measurements and SEM-EDX data. Structural characterization was performed with powder-XRD, FTIR and magnetization measurements. Morphological analyses were conducted with electron microscopy imaging (SEM and TEM). Thermal stabilities were investigated by TGA/DTA. Carborane release from LDH layers was tested by tracing the amount of boron species transferred to the solution phase with ICP-MS measurements. The results verified that the prepared nanohybrids have the potential to be used in Boron Neutron Capture Therapy (BNCT) and magnetically targeted-BNCT applications.

Synthesis of Fe 3 O 4 /Eggshell Nanocomposite and Application for Preparation of Tetrahydrobenzo[b]Pyran Derivatives

This work is reported on the synthesis of Fe3O4/eggshell nanocomposites in the absence of any stabilizer or surfactant. Fe3O4 magnetic nanoparticles were established on the egg shell nano-composite. The nanocompositeshave shown high catalytic activities in the synthesis of Tetrahydrobenzo[b]pyran. These derivatives were synthesized via an one‐pot three‐component condensation of aromatic aldehydes with malononitrile and dimedonewith excellent yields in the presence of Fe3O4/eggshell nanocomposites as a highly efficient heterogeneous catalyst. The obtained catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD) and Vibrating sample magnetometer (VSM). The developed technique of nano-composite synthesis is energy efficient since the reactions carried out in single step. The present catalyst is possible to be used for the production of biodiesel.

Metal–Hydroxide and Gold–Nanocluster Interfaces: Enhancing Catalyst Activity and Stability for Oxygen Evolution Reaction

By engineering the interaction between the transition metal ions (M = Mn2+, Co2+, and Ni2+) and the nanorod-shaped assemblages of Au nanoclusters (AuNCs), a series of tubular AuNCs@M(OH)2 core–shell nanocomposites are produced in which numerous AuNCs are embedded beneath a thin layer of metal hydroxide with thickness below 4 nm and where the AuNCs within the same assemblage are partially connected with each other. Because of the synergistic effects from the abundant presence of the AuNCs–M(OH)2 interfaces, the AuNCs@M(OH)2 (M = Co and Ni) nanocomposites demonstrate evidently enhanced activity for oxygen evolution reaction (OER) in alkaline condition. Overpotentials of 0.350 and 0.375 V have been obtained at the current density of 10 mA cm–2 in 0.1 M KOH for the AuNCs@Co(OH)2 and AuNCs@Ni(OH)2, respectively. And at the overpotential of 0.42 V, the current density of AuNCs@M(OH)2 (M = Co and Ni) nanocomposites is more than 10 times of those generated by their respective metal hydroxides. Compared with monop...

Indocyanine Green-Loaded Silver Nanoparticle@Polyaniline Core/Shell Theranostic Nanocomposites for Photoacoustic/Near-Infrared Fluorescence Imaging-Guided and Single-Light-Triggered Photothermal and Photodynamic Therapy.

Photoacoustic (PA)/near-infrared fluorescence (NIRF) dual-modal imaging-guided phototherapy has been wide explored very recently. However, the development of high-efficiency and simplified-performed theranostic system for amplifying imaging-guided photothermal therapy/photodynamic therapy (PTT/PDT) is still a great challenge. Herein, a single-light-triggered indocyanine green (ICG)-loaded PEGylation silver nanoparticle core/polyaniline shell (Ag@PANI) nanocomposites (ICG-Ag@PANI) for PA/NIRF imaging-guided enhanced PTT/PDT synergistic effect has been successfully constructed. In this study, the synthesized Ag@PANI nanocomposites are utilized not only as the promising photothermal agent but also as potential nanovehicles for loading photosensitizer ICG via π-π stacking and hydrophobic interaction. The as-prepared ICG-Ag@PANI possesses many superior properties such as strong optical absorption in the near-infrared (NIR) region, enhanced photostability of ICG, as well as outstanding NIR laser-induced local hyperthermia and reactive oxygen species (ROS) generation. In the in vivo study, PA/NIRF dual-modal imaging confirms the accumulation and distribution of ICG-Ag@PANI in the tumor region via enhanced permeability and retention (EPR) effect. Moreover, the PTT effect of ICG-Ag@PANI rapidly raised the tumor temperature to 56.8 °C within 5 min. It is also demonstrated that the cytotoxic ROS generation ability of ICG is well maintained after being loaded onto Ag@PANI nanocomposites. Remarkably, in comparison with PTT or PDT alone, the single 808 nm NIR laser-triggered combined PTT/PDT therapy exhibits enhanced HeLa cells lethality in vitro and tumor growth inhibition in vivo.

Highly stable magnetically separable copper nanocatalyst as an efficient catalyst for C(sp2)–C(sp) and C(sp2)–C(sp2) cross‐coupling reactions

A copper catalyst has been explored as an efficient and recyclable catalyst to effect Sonogashira and Suzuki cross‐coupling reactions. After modification of 2‐(((piperazin‐1‐ylmethyl)imino)methyl)phenol (PP) on the surface of amorphous silica‐coated iron oxide (Fe3O4@SiO2@Cl) magnetic core–shell nanocomposite, copper(II) chloride was employed to synthesize the Fe3O4@SiO2@PP‐Cu catalyst, affording a copper loading of 1.52 mmol g−1. High yield, low reaction times, non‐toxicity and recyclability of the catalyst are the main merits of this protocol. The catalyst was characterized using Fourier transform infrared, X‐ray photoelectron, energy‐dispersive X‐ray and inductively coupled plasma optical emission spectroscopies, X‐ray diffraction, scanning and transmission electron microscopies, and vibrating sample magnetometry.

Green synthesis of Pd/walnut shell nanocomposite using Equisetum arvense L. leaf extract and its application for the reduction of 4-nitrophenol and organic dyes in a very short time.

Palladium nanoparticles (PdNPs) have been immobilized on the surface of walnut shell powder using Equisetum arvense L. leaf extract as reducing and stabilizing agents in this work. FT-IR spectroscopy, UV-Vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction (XRD) pattern, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) have been used in the characterization of the nanocomposites thus prepared. High catalytic activity was shown by these nanocomposites in the reduction of different dyes. The PdNPs' diameter on the walnut shell was predominantly found within the 5-12-nm range. The advantages of these catalysts include facile and clean synthesis, simple preparation procedure, excellent properties, alterable supports, and low cost, which make them applicable in reduction of 4-nitrophenol (4-NP), Congo red (CR), methylene blue (MB), and rhodamine B (RhB) in the presence of aqueous NaBH4 at room temperature. Pd/walnut shell nanocomposites were highly active catalysts for reduction of these dyes. Moreover, Pd/walnut shell nanocomposite can be recovered and recycled seven times without any appreciable loss of catalytic activity. Graphical abstract Waste walnut shell as a natural valuable resource support for green synthesis of Pd/walnut shell nanocomposite using Equisetum arvense L. leaf extract and its application for the reduction of 4-nitrophenol and organic dyes in a very short time.

Controlled one-step synthesis of CdS@ZnS core–shell particles for efficient photocatalytic hydrogen evolution

Core–shell CdS@ZnS nanocomposites are directly grown on indium tin oxide (ITO) substrate without conductive additives and contamination of organic surfactants via a one-step hydrothermal method. Performed CdS@ZnS core–shell nanocomposites are evolved from ZnO nanowires by reacting with CdS precusors at 100 °C for 5 h. The shell thickness could be tuned by varying the CdS precursor, and the porous structure with 40 nm shell exhibited improved hydrogen evolution of around 5700 μmol cm−2, 1.5 times higher than that of structure with 20 nm shell. Protective ZnS shell can effectively passivate the surface trap states of the CdS cores, greatly improving the photocatalytic activities of the CdS@ZnS core–shell architecture. The core–shell heterostructure with the staggered band alignments facilitates the separation and transport of the photoexcited charge carriers, and the localized acceptor states induced by intrinsic defects provide pathway for carriers transport.

Influence of ZnO concentration on the optical and photocatalytic properties of Ni-doped ZnS/ZnO nanocomposite

Photocatalysts consisting of nickel-doped ZnS/ZnO core shell nanocomposites with varying concentrations of ZnO was synthesized through chemical precipitation method. The catalyst was deployed in photocatalytic degradation of indigo carmine dye as a model organic pollutant. Characterization of the samples was achieved through the use of X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, UV–vis spectroscopy and energy dispersive spectroscopy. The composites consist of wurtzite ZnO phase deposited on cubic ZnS. Optical absorption, crystallite sizes and photocatalytic degradation efficiency increased with increasing ZnO concentration. Bandgap values of ZnS also decreased appreciably with increase in ZnO concentration. Ni-doped ZnS/(0.5 M ZnO) was identified as the most efficient catalyst with 91% dye degradation efficiency at a rate of 15.38 × 10−3 min−1 in 180 min. Meanwhile, the pristine ZnS degraded 25% of the dye at the rate of 1.53 × 10−3 min−1 within the same time. The Ni-doped Zns/(0.5 M ZnO) was used to degrade the dye on the basis of influence of factors such as solution temperature, hydrogen peroxide (H2O2) and ethanol contents. Dye degradation increased with increase in temperature, but decreased with ethanol content. H2O2 content initially caused enhanced dye degradation but the efficiency decreased with higher H2O2 content.

Photocatalytic activity of ZnO-MnO2 core shell nanocomposite in degradation of RhB dye

Purpose The purpose of this study is to synthesize a semiconductor photocatalyst which responds to both UV light and visible light in removal of organic dyes. Design/methodology/approach ZnO nanoparticles were pre-synthesised via sol-gel method using zinc nitrate tetrahydrate and methanamine at 90°C for 20 h. Subsequently, the as-synthesised ZnO nanoparticles were filtered, washed and dried. To synthesize ZnO-MnO2 core shell nanocomposites (CSNs), 2:3 M ratio of KMnO4 and MnSO4 solution was stirred for an hour. Next, ZnO nanoparticles were added into the solution. The solution was heated at 160°C for 3 h for the formation of ZnO-MnO2 CSNs. The structural, optical and photocatalytic properties of ZnO-MnO2 CSNs were characterised by field emission scanning electron microscope, transmission electron microscopy (TEM), X-ray diffractometer and PL spectroscopy, respectively. Findings The photodegradation efficiencies of rhodamine B (RhB) dye by ZnO-MnO2 CSNs as photocatalysts are 87.1 per cent under UV irradiation and 76.6 per cent under visible light irradiation, respectively. Their corresponding rate constants are 0.016 min−1 under UV irradiation and 0.013 min−1 under visible light irradiation. It can be concluded that N-deethylation was the dominant step during the photodegradation of RhB dye as compared to cycloreversion. The ZnO-MnO2 CSNs demonstrated good photostability after three consecutive runs. Originality/value ZnO-MnO2 CSN photocatalyst which could response to UV and visible light in degradation of RhB dye was synthesised using sol-gel method. The analysis shows that N-deethylation was the key photodegradation mechanism of RhB by ZnO-MnO2 CSN.

Green, Multi-Gram One-Step Synthesis of Core-Shell Nanocomposites in Water and Their Catalytic Application to Chemoselective Hydrogenations.

We devise a new and green route for the multi-gram synthesis of core-shell nanoparticles (NPs) in one step under organic-free and pH-neutral conditions. Simply mixing core and shell metal precursors in the presence of solid metal oxides in water allowed for the facile fabrication of small CeO2 -covered Au and Ag nanoparticles dispersed on metal oxides in one step. The CeO2 -covered Au nanoparticles acted as a highly efficient and reusable catalyst for a series of chemoselective hydrogenations, while retaining C=C bonds in diverse substrates. Consequently, higher environmental compatibility and more efficient energy savings were achieved across the entire process, including catalyst preparation, reaction, separation, and reuse.

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.

Synthesis and characterization of composites of ceramic nano-particles with non-conducting polymers for dielectric materials production

In the present study sol–gel [1] method was successfully used to synthesize nanoparticles of Fe1.46Zn0.5La0.04Cu0.504O4 (FLZCs). High resolution scanning electron microscopy (HRSEM) specified the formation of granular nano spheres beside an intermediated phase of nanowires. Polymer-blended magnetic materials were obtained using poly (vinyl pyrrolidone) (PVP), poly (vinyl alcohol), poly (ethylene Glycol) and Poly (ethylene oxide) as capping agents. This coating strategy controls the agglomeration of ferrite nanoparticles, and produces a well-designed core–shell nano-assembly with enhanced physical properties. X-ray Diffraction and HRSEM confirmed the formation of ferrite as a core surrounded by various polymeric shells. The nanocomposites with PVP shell resulted in increased ac conductivity (r) of about four orders of magnitude higher than that recorded for the pure ferrite. These novel results indicate that such series of core–shell nanocomposites are promising candidates in industrial applications such as electro-active materials and magnetic substances. Moreover, this study emphasized that ferrite nanoparticles are good additive to non-conducting polymers when blended in the form of core–shell nanocomposite structure.

Porous ZnO@C core–shell nanocomposites as high performance electrode materials for rechargeable lithium-ion batteries

A novel porous spherical ZnO@carbon (C) nanocomposite based on zeolitic imidazolate frameworks (ZIFs-8)-directed method was prepared for lithium-ion batteries (LIBs). In this strategy, spherical ZnO nanoparticles were firstly prepared, then 2-methylimidazolate and Zn2+ were added alternately under ultrasound to fabricate ZnO@ZIF-8. Finally, the novel porous spherical ZnO@C nanocomposites were obtained via pyrolyzing the corresponding ZnO@ZIF-8. The novel porous spherical ZnO@C nanocomposites were characterized with different analysis techniques such as scanning electron microscopy, transmission electron microscopy and X-ray powder diffraction. The resulted spherical ZnO@C nanocomposites exhibited a high reversible capacity of 932 mA h g−1 at 0.1 A g−1 after 100 cycles, which is much higher than that of the pure ZnO nanoparticles. The porous structure, high specific surface area and good electrical conductivity eventually contribute to the good performance of the resulted ZnO@C nanocomposites for LIBs should be ascribed to the proous structure and high BET surface area derived from ZIFs, as well as the good electrical conductivity of the amourphous carbon derived from ZIFs.

Synthesis of β–NaYF4: Yb3+, Tm3+ @ TiO2 and β–NaYF4: Yb3+, Tm3+ @ TiO2 @ Au nanocomposites and effective upconversion–driven photocatalytic properties

The β–NaYF4: Yb3+, Tm3+ @ TiO2 nanocomposite has been prepared by a facile hydrothermal method followed by the hydrolysis of TBOT, and then NaYF4: Yb3+, Tm3+ @ TiO2, HAuCl4 and sodium citrate were put into an oil bath for reaction to obtain the β–NaYF4: Yb3+, Tm3+ @ TiO2 @ Au core–shell nanocomposite. XRD and HRTEM show that the samples exhibit the hexagonal phase NaYF4, anatase TiO2 and cubic Au, indicating that the core–shell phases of NaYF4−TiO2 or NaYF4−TiO2−Au coexist in these samples. EDS and XPS results show the presence of Na, Y, F, Ti, O and Au elements. When TiO2 was coated on the surface of upconversion nanomaterials of NaYF4: Yb3+, Tm3+, the photocatalytic activity was improved significantly, and the β–NaYF4: Yb3+, Tm3+ @ TiO2 nanocomposite gives the highest photodegradation efficiency for MB and RhB, and decomposes about 73% of MB or 80% of RhB within 4.5 h under simulated solar light irradiation respectively. When the ultraviolet light from simulated sunlight irradiation was removed by the addition of a UV filter, the β–NaYF4: Yb3+, Tm3+ @ TiO2 nanocomposite decomposes about 42% of MB or 48% of RhB within 4.5 h. It means that the upconversion–driven photocatalytic performance (decomposes 42% of MB or 48% of RhB) is more effective than UV light–driven photocatalytic performance (31% of MB or 32% of RhB) in the photodegradation process. In addition, the β–NaYF4: Yb3+, Tm3+ @ TiO2 @ Au core–shell nanocomposite does not exhibit the better photocatalytic activity, and the optimal research will be carried out in the future.