Core-shell Structure Nanoparticles Research Articles

Synthesis mechanism, enhanced visible-light-photocatalytic properties, and photogenerated hydroxyl radicals of PS@CdS core–shell nanohybrids

In this study, spherical polystyrene (PS)@CdS core–shell structure nanoparticles (CSNPs) were prepared by sonochemical method. The influences of the surfactant PVP, the order of adding precursors, the molar ratio of S/Cd, and the reaction time on structure were carefully studied. Results of SEM, TEM, EDS, XRD, and FT-IR showed that the as-prepared nanohybrids have a typical core–shell structure with 260 nm core and a uniform shell with thickness ranging from 10 to 30 nm, both PVP and the order of adding precursors were the controlling parameters. In addition, the as-synthesized PS@CdS CSNPs exhibited much higher photocatalytic activity for RhB under visible light irradiation compared with pure CdS, which should be attributed to their synergic effect between core and shell, amount of hydroxyl groups on the surface, good monodispersity, and so on. Besides, the production of photogenerated hydroxyl radical (•OH) was in accordance with the RhB decolorization efficiency from the prepared PS@CdS CSNPs. It indicated that •OH was the main active oxygen species in the photocatalytic process.

Dual Drug Release from Core–Shell Nanoparticles with Distinct Release Profiles

Multiple drug combination is a promising strategy in biomedical fields, such as cancer chemotherapy and tissue engineering. With the aim of codelivering multiple drugs with different characteristics, immiscible and miscible liquids were utilized to fabricate nanoparticles of polyvinylpyrrolidone/poly(lactic-co-glycolic acid) (PLGA) and poly(ε-caprolactone)/PLGA with distinct core-shell structure by coaxial electrospray. Each kind of nanoparticles can encapsulate the hydrophilic rhodamine B and hydrophobic naproxen in one single step efficiently. Encapsulation efficiency was over 85%. The different release patterns of dual-drug encapsulated were demonstrated when the drug location swapped, attributing to the distinct core-shell structures of nanoparticles and the interaction between drug molecules and carrier polymers. Meanwhile, the release profiles of encapsulated drugs with different loading amount were investigated as well. Dual drug release profiles from nanoparticles were affected by the unique architecture of nanocarriers (porous and core-shell structure), physical properties of polymers, and drugs. In addition, polymer-drug and drug-drug molecular interaction may take an important role in drug release behaviors. The results suggested that the distinct release kinetics of multiple drugs fabricated by coaxial electrospray can be obtained and tuned to fulfill the clinical requirement in combination therapy.

PREPARATION AND CHARACTERIZATION OF SURFACE-FUNCTIONALIZATION OF SILICA-COATED MAGNETITE NANOPARTICLES FOR DRUG DELIVERY

Fe 3 O 4– SiO 2 core–shell structure nanoparticles containing magnetic properties were investigated for their potential use in drug delivery. The Fe 3 O 4– SiO 2 core–shell structure nanoparticles were successfully synthesized by a simple and convenient way. The Fe 3 O 4– SiO 2 nanoparticles showed superparamagnetic behavior, indicating a great application potential in separation technologies. From the application point of view, the prepared nanoparticles were found to act as an efficient drug carrier. Specifically, the surface of the core–shell nanoparticles was modified with amino groups by use of silane coupling agent 3-aminopropyltriethoxysilane (APTS). Doxorubicin (DOX) was successfully grafted to the surface of the core–shell nanoparticles after the decoration with the carboxyl acid groups on the surface of amino-modified core–shell structure nanoparticles. Moreover, the nanocomposite showed a good drug delivery performance in the DOX-loading efficiency and drug release experiments, confirming that the materials had a great application potential in drug delivery. It is envisioned that the prepared materials are the ideal agent for application in medical diagnosis and therapy.

Microwave assisted hydrothermal synthesis of well-dispersed and thermally stable Ag@SnO2 core–shell nanocomposites for propane sensing applications

A simple microwave assisted hydrothermal precipitation (M–H) technique for the synthesis of Ag@SnO2 core–shell structure nanoparticles (NPs) is reported. Ag NPs were synthesized via chemical reduction of metal salt followed by M–H deposition of tin dioxide shell for fabrication of monodispersed core–shell particles. The phase and morphology has been investigated by X-ray diffraction technique (XRD) and transmission electron microscopy (TEM) respectively. Ag@SnO2 core–shell nanocomposites have shown distinct surface Plasmon spectrum in the range of 407–440 nm. The core–shell morphology is confirmed from the TEM images. XRD patterns have suggested the formation of silver and tin dioxide in the face-centered cubic and Cassiterite form respectively. Our investigations suggested that the formation of core–shell structure results in the enhanced thermal stability of the system. Synthesized material is used for the detection of propane gas. To understand the multi gas sensing ability and selectivity for detection of propane gas by Ag@SnO2 core–shell materials based devices, Sinha–Tripathy soft-sensor model has been proposed.

The Synthesis of Magnetic Lysozyme‐Imprinted Polymers by Means of Distillation–Precipitation Polymerization for Selective Protein Enrichment

A protein imprinting approach for the synthesis of core-shell structure nanoparticles with a magnetic core and molecularly imprinted polymer (MIP) shell was developed using a simple distillation-precipitation polymerization method. In this work, Fe3O4 magnetic nanoparticles were first 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 MIP shell was coated onto the surface of the magnetic nanoparticles by the copolymerization of functional monomer acrylamide (AAm), cross-linking agent N,N'-methylenebisacrylamide (MBA), the initiator azodiisobutyronitrile (AIBN), and protein in acetonitrile heated at reflux. The morphology, adsorption, and recognition properties of the magnetic molecularly imprinted nanoparticles were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and rebinding experiments. The resulting MIP showed a high adsorption capacity (104.8 mg g(-1)) and specific recognition (imprinting factor=7.6) to lysozyme (Lyz). The as-prepared Fe3O4@Lyz-MIP nanoparticles with a mean diameter of 320 nm were coated with an MIP shell that was 20 nm thick, which enabled Fe3O4@Lyz-MIP to easily reach adsorption equilibrium. The high magnetization saturation (40.35 emu g(-1)) endows the materials with the convenience of magnetic separation under an external magnetic field and allows them to be subsequently reused. Furthermore, Fe3O4@Lyz-MIP could selectively extract a target protein from real egg-white samples under an external magnetic field.

Modelling transport in nanoparticle organic solar cells using Monte Carlo methods

Water-based nanoparticle (NP) organic solar cells eliminate the need for harmful organic solvents during deposition. However, the core-shell NP structure should limit charge extraction resulting in poor performance. Here, we use dynamic Monte Carlo modelling to show that for optimised NP structures the core-shell character does not severely limit performance. Simulations further reveal that small NPs are more susceptible to extensive phase segregation, which diminishes charge carrier percolation pathways from the cores to the electrodes and thus inhibits charge extraction. Simulated performance behaviour was used to propose an explanation for the experimentally observed change in performance due to annealing.

Core–shell molecularly imprinted polymer nanoparticles with assistant recognition polymer chains for effective recognition and enrichment of natural low-abundance protein

Core–shell molecular imprinting of nanomaterials overcomes difficulties with template transfer and achieves higher binding capacities for macromolecular imprinting, which are more important to the imprinting of natural low-abundance proteins from cell extracts. In the present study, a novel strategy of preparing core–shell nanostructured molecularly imprinted polymers (MIPs) was developed that combined the core–shell approach with assistant recognition polymer chains (ARPCs). Vinyl-modified silica nanoparticles were used as support and ARPCs were used as additional functional monomers. Immunoglobulin heavy chain binding protein (BiP) from the endoplasmic reticulum (ER) was chosen as the model protein. The cloned template protein BiP was selectively assembled with ARPCs from their library, which contained numerous limited-length polymer chains with randomly distributed recognition and immobilization sites. The resulting complex was copolymerized onto the surface of vinyl-modified silica nanoparticles under low concentrations of the monomers. After template removal, core–shell-structured nanoparticles with a thin imprinted polymer layer were produced. The particles demonstrated considerably high adsorption capacity, fast adsorption kinetics and selective binding affinities toward the template BiP. Furthermore, the synthesized MIP nanoparticles successfully isolated cloned protein BiP from protein mixtures and highly enriched BiP from an ER extract containing thousands of kinds of proteins. The enrichment reached 115-fold and the binding capacity was 5.4μgg−1, which were higher than those achieved by using traditional MIP microspheres. The advantageous properties of MIP nanoparticles hold promise for further practical applications in biology, such as protein analysis and purification.

Fabrication, structure, and property of epoxy-based composites with metal–insulator core–shell structure fillers

Abstract

Molecular dynamics simulations on the melting, crystallization, and energetic reaction behaviors of Al/Cu core-shell nanoparticles

Using molecular dynamics simulations combined with the embedded atom method potential, we investigate the heating, cooling, and energetic reacting of core-shell structured Al-Cu nanoparticles. The thermodynamic properties and structure evolution during continuous heating and cooling processes are also investigated through the characterization of the total potential energy distribution, mean-square-distance and radial distribution function. Some behaviors related to nanometer scale Cu/Al functional particles are derived that two-way diffusion of Al and Cu atoms, glass phase formation for the fast cooling rate, and the crystal phase formation for the low cooling rate. Two-way atomic diffusion occurs first and causes the melting and alloying. In the final alloying structure, Cu and Al atoms mixed very well except for the outmost shell which has more Al atoms. For the investigation of the thermal stability and energetic reaction properties, our study show that a localized alloying reaction between the Al core and Cu shell is very slow when the initial temperature is lower than 600 K. But a two-stage reaction may occur when the initial temperature is 700 K. The reaction rate is determined by the solid-state diffusion of Al atoms in the Cu shell at the first stage, yet the reaction rate is much faster at the second stage, due to the alloying reaction between the liquid Al core and the Cu shell. At higher temperatures such as 800 K and 900 K, the alloying reaction occurs directly between the liquid Al core and the Cu shell.

Toughening Poly (Vinyl Chloride) by PS/PB/PMMA Three-Layer Particles

Three-layer core-shell structural nanoparticles, poly styrene/polybutadiene/poly (methyl methacrylate) (PSBM) were synthesized via emulsion graft polymerization method. The toughening efficiency of PSBM was compared with MBS(methyl methacrylate-butadiene-styrene copolymer) for PVC matrix. It was found that the large differences in impact strength between PSBM and MBS arised from the structure characteristics and cavitation ability of rubber. The higher tensile modulus of PVC toughened with PSBM was directly related to the presence of hard PS glassy domains in the core, which acted as stiffening agents. It was also found that the multi-interface layer of modifier particles was a disadvantage for obtaining transparency of blends.

Delivery of Paclitaxel and Berbamine by Polymeric Carriers to Cure Gastric Cancer

Successful chemotherapy needs to reduce the toxic side effects against normal tissues and avoid the detriments caused by intolerable solvents. Drug delivery systems using soluble polymeric nanoparticles tend to be the focus. In the current study, core-shell structure nanoparticles were prepared from block copolymer of methoxy poly(ethylene glycol)-polycaprolactone (mPE-PCL). Paclitaxel (PTX) and berbamine (BA) were incorporated into mPEG-PCL nanoparticles. It was found in our study that PTX and BA can be incorporated into the nanoparticles with high encapsulation efficiency. In vitro release study showed that PTX and BA were released from nanoparticles in a sustained manner. In vitro cytotoxicity studies indicated that PTX/BA coloaded nanoparticles (PTX/BA-np) show dose- and time-dependent cytotoxicity again BGC823 cells. Furthermore, intratumoral administration was applied to improve the tumor-targeted delivery in the in vivo evaluation. Compared with free drugs, PTX/BA-np exhibited superior antitumor effect by delaying tumor growth when delivered intratumorally. These results suggest that PTX/BA-np are effective to inhibit the growth of human gastric cancer and merit more research to evaluate the feasibility of clinical application.

Exploiting Core–Shell Synergy for Nanosynthesis and Mechanistic Investigation

The core-shell nanoparticle structure, which consists of an inner layer "guest" nanoparticle encapsulated inside another of a different material, is the simplest motif in two-component systems. In comparison to the conventional single-component systems, complex systems pose both challenges and opportunities. In this Account, we describe our recent progresses in using core-shell motif for exploring new and sophisticated nanostructures. Our discussion is focused on the mechanistic details, in order to facilitate rational design in future studies. We believe that systematic development of synthetic capability, particularly in complex and multifunctional systems, is of great importance for future applications. A key issue in obtaining core-shell nanostructures is minimizing the core-shell interfacial tension. Typically, one can coat the core with a ligand for better interaction with the shell. By selecting suitable ligands, we have developed general encapsulation methods in three systems. A variety of nanoparticles and nanowires were encapsulated using either amphiphilic block copolymer (polystyrene-block-poly(acrylic acid)), conductive polymer (polyaniline, polypyrrole, or polythiophene), or silica as the shell material. Obvious uses of shells are to stabilize colloidal objects, retain their surface ligands, prevent particle aggregation, or preserve the assembled superstructures. These simple capabilities are essential in our synthesis of surface-enhanced Raman scattering nanoprobes, in assigning the solution state of nanostructures before drying, and in developing purification methods for nano-objects. When it is applied in situ during nanocrystal growth or nanoparticle assembly, the intermediates trapped by shell encapsulation can offer great insights into the mechanistic details. On the other hand, having a shell as a second component provides a window for exploring the core-shell synergistic effects. Hybrid core-shell nanocrystals have interesting effects, for example, in causing the untwisting of nanowires to give double helices. In addition, partial polymer shells can bias nanocrystal growth towards one direction or promote the random growth of Au dendritic structures; contracting polymer shells can compress the embedded nanofilaments (Au nanowires or carbon nanotubes), forcing them to coil into rings. Also, by exploiting the sphere-to-cylinder conversion of block copolymer micelles, the Au nanoparticles pre-embedded in the polymer micelles can be assembled into long chains. Lastly, shells are also very useful for mechanistic studies. We have demonstrated such applications in studying the controlled aggregation of nanoparticles, in probing the diffusion kinetics of model drug molecules from nanocarriers to nanoacceptors, and in measuring the ionic diffusion through polyaniline shells.

Lithium Superionic Sulfide Cathode for All-Solid Lithium–Sulfur Batteries

This work presents a facile synthesis approach for core-shell structured Li2S nanoparticles with Li2S as the core and Li3PS4 as the shell. This material functions as lithium superionic sulfide (LSS) cathode for long-lasting, energy-efficient lithium-sulfur (Li-S) batteries. The LSS has an ionic conductivity of 10(-7) S cm(-1) at 25 °C, which is 6 orders of magnitude higher than that of bulk Li2S (∼10(-13) S cm(-1)). The high lithium-ion conductivity of LSS imparts an excellent cycling performance to all-solid Li-S batteries, which also promises safe cycling of high-energy batteries with metallic lithium anodes.

Synthesis of thermally stable monodispersed Au@SnO2 core–shell structure nanoparticles by a sonochemical technique for detection and degradation of acetaldehyde

A simple ultrasound assisted chemical precipitation technique for the synthesis of Au@SnO2 core–shell structure nanoparticles is reported. Au nanoparticles were synthesized via chemical reduction of metal salt followed by sonochemical deposition of a tin dioxide shell with controlled shell thickness. The phase and morphology have been investigated by an X-ray diffraction technique (XRD) and transmission electron microscopy (TEM) respectively. Au@SnO2 core–shell nanocomposites have shown a distinct surface plasmon peak in the UV-visible spectrum at 540 nm. The core–shell morphology is confirmed from the TEM images. XRD patterns have suggested the formation of gold and tin dioxide in the face-centered cubic and Cassiterite form respectively. Our investigations suggested that the formation of a core–shell structure results in the enhanced thermal stability of the system. The synthesized material is used for the detection and oxidation of acetaldehyde gas. Our investigations suggest the potential application of sonochemically synthesized Au@SnO2 nanoparticles for realization of a sense and shoot device for indoor air purification.

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.

Au/SnO2core-shell 나노구조 센서의 구동온도가 CO 감동에 미치는 영향

Au/<TEX>$SnO_2$</TEX> core-shell structure nanoparticles (NPs) were synthesized by microwave hydrothermal method, and the effect of working temperature on sensitivity of Au/<TEX>$SnO_2$</TEX> core-shell NPs for CO gas was investigated. The <TEX>$SnO_2$</TEX> shell layer was consisted of <TEX>$SnO_2$</TEX> primary particles with 4.5 nm diameter. The response of Au/<TEX>$SnO_2$</TEX> core-shell NPs for CO gas was maximized at the working temperature of <TEX>$350^{\circ}C$</TEX> while the sensitivity increased with decreasing the working temperature due to the low grain size effect of <TEX>$SnO_2$</TEX> NPs on the response of CO gas.

Preparation of magnetic polyurethane rigid foam nanocomposites

Super paramagnetic Fe3O4@SiO2 nanoparticle was incorporated into polyurethane rigid foams in order to prepare new corresponded magnetic nanocomposite foams via one-shot method. The core–shell-structured nanoparticles were prepared by sol–gel method and characterized by transmission electron microscopy, X-ray diffraction, as well as Fourier transform infrared spectroscopy techniques. Magnetic nanoparticles were used up to 3 % in the foam formulations and the samples prepared successfully. Thermal, mechanical, and magnetic properties of nanocomposites were studied and the results showed superior properties in comparison with pristine foams.

Development of Gold Nanoparticle Radiotracers for Investigating Multiphase System in Process Industries

This paper describes the development of colloidal Au-SiO2 with core-shell structure nanoparticle radioactive tracers by neutron activation in nuclear reactor that produce Au-198 (T1/2=2.7 d) emitting gamma ray of 412 keV. Using conventional citrate-reduction method, gold nanoparticles were prepared from its corresponding metal salts in aqueous solution then coated with uniform shells of amorphous silica via a sol-gel reaction. The citrate-reduction-based method provides gold nanoparticles with higher concentration and narrow size distribution. By using transmission electron microscopy (TEM), the resultant of particle size and silica coatings could be varied from tens to several hundred of nanometers by controlling the catalyzer and precipitation time. Au-SiO2 core-shell nanostructure is good to prevent the particles from getting agglomerated resulting in a big mass. In addition, silica surface offer very good chances that make the hydrophobic and hydrophilic behavior on the gold nanoparticles. EDXRF spectrum has proven that Au-SiO2 core-shell nanoparticles sample consists purely of a gold and silica particles. This target material of radiotracer application used to investigate multiphase system in process industries without disturbing the system operation.

Synthetic core–shell Ni@Pd nanoparticles supported on graphene and used as an advanced nanoelectrocatalyst for methanol oxidation

In this study, the uniform dispersion of new highly active Ni@Pd core–shell nanoparticle catalysts supported on graphene (Ni@Pd/graphene) was prepared via a two-step procedure involving a microwave synthesis method and a replacement method. Several characterization tools, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to study the phase structures, morphologies and properties of the Ni@Pd/graphene composite. The results indicated that a uniform dispersion of Ni@Pd core–shell structure nanoparticles on graphene have an average particle size of 4 nm. The Ni@Pd/graphene composite was used as an electrocatalyst for alcohol oxidation in alkaline media for fuel cells. The electrocatalytic activity of Ni@Pd/graphene for ethanol oxidation is 3 times higher than that of the Pd/graphene electrocatalyst at the same Pd loading. The enhanced electrocatalytic properties could be attributed not only to the electric synergistic effect between Pd, Ni and graphene, but also the high use ratio of Pd due to its shell structure.

Microstructure and CO gas sensing property of Au/SnO2 core–shell structure nanoparticles synthesized by precipitation method and microwave-assisted hydrothermal synthesis method

Au/SnO2 core–shell structure NPs were prepared by a precipitation method and a microwave hydrothermal synthesis method, and their CO responses were measured by a high resistance meter. It was found that the CO response of the sample prepared by the precipitation method was extremely low, 0.18, with comparison to the one by the hydrothermal synthesis method, 0.965. Microstructures achieved by two-dimensional TEM characterization showed that both samples maintained the similar core–shell structures with their sizes ranging between 30 and 50nm, as the core consists of Au NP and the shell consists of SnO2 NPs. The average grain sizes of SnO2 NPs of precipitation method and hydrothermal synthesis method were measured as 5.2nm and 8.3nm, respectively. The thickness and the porosity variation of SnO2-shell layers were characterized further by three-dimensional electron tomography, and correlated with the sensing properties. It was found that the porosity within SnO2-shell layers prepared by the precipitation method was lower than the one prepared by the hydrothermal synthesis method. Since Au NP could act as the catalyst for CO oxidation reaction, high porosity within SnO2-shell layers would have lead the accessibilities of Au NP to the CO gas molecules and resulted high CO responses.