A facile solution phase synthesis of directly ordering monodisperse FePt nanoparticles

The ordered Pt-based intermetallic nanoparticles(NPs)with small size show superior magnetic or catalytic properties,but the synthesis of these NPs still remains a great challenge due to the requirement of high temperature annealing for the formation of the ordered phase,which usually leads to sintering of the NPs.Here,we report a simple approach to directly synthesize monodisperse ordered L1₀-FePt NPs with average size 10.7 nm without further annealing or doping the third metal atoms,in which hexadecyltrimethylammonium chloride(CTAC)was found to be the key inducing agent for the thermodynamic growth of the Fe and Pt atoms into the ordered intermetallic structure in the synthetic process.In particular,10.7 nm L1₀-FePt NPs synthesized by the proper amount of CTAC show a coercivity of 3.15 kOe and saturation magnetization of 45 emu/g at room temperature.The current CTAC-assisted synthetic strategy makes it possible to deeply understand the formation of the ordered Pt-based intermetallic NP in solution phase synthesis.     

Sodium lanthanide fluoride core-shell nanocrystals: A general perspective on epitaxial shell growth

Understanding the structural characteristics and growth mechanism（s） are essen-tial for generating core-shell nano-heterostructures with distinctive properties. Especially in lanthanide-based nanocrystals, rational design of the core-shell composition can be utilized to enhance/tune the optical properties of the final nanostructure, or can be used to integrate multiple functional applications （e.g., luminescent/magnetic）. In this article, we review the progress in our current understanding of the epitaxial shell growth in sodium lanthanide fluoride （NaLnF4） nanocrystals. In order to understand epitaxial shell growth the core nanocrystals have to be uniform, and to date the synthesis of high quality near uniform size/shape dispersion controlled synthesis of lanthanide-based nanocrystals has been achieved mainly with this class of nanocrystals. The progress in core-shell synthesis and the epitaxial shell growth mechanism in this class of nanocrystals （NaLnF4） are reviewed, and a general perspective is provided on the core-shell morphology based on different characterization techniques. While there has been tremendous progress in studying the impact of core-shell structures in various functional applications, this review also highlights, in our view, the still limited understanding of ways to control the core-shell morphology and it emphasizes some important, unanswered questions that remain to be addressed to maximize their performance.     

Paclitaxel-loaded hollow-poly(4-vinylpyridine) nanoparticles enhance drug chemotherapeutic efficacy in lung and breast cancer cell lines

Paclitaxel (PTX),one of the most effective cytotoxins for the treatment of breast and lung cancer,is limited by its severe side effects and low tumor selectivity.In this work,hollow-poly(4-vinylpyridine) (hollow-p4VP) nanoparticles (NPs) have been used for the first time to generate PTX@p4VP NPs,employing a novel technique in which a gold core in the center of the NP is further oxidized to produce the hollow structure into which PTX molecules can be incorporated.The hollow-p4VP NPs exhibit good physicochemical properties and displayed excellent biocompatibility when tested on blood (no hemolysis) and cell cultures (no cytotoxicity).Interestingly,PTX@p4VP NPs significantly increased PTX cytotoxicity in human lung (A-549) and breast (MCF-7) cancer cells with a significant reduction of PTX IC50 (from 5.9 to 3.6 nM in A-549 and from 13.75 to 4.71 nM in MCF-7).In addition,PTX@p4VP caused a decrease in volume of A-549 and MCF-7 multicellular tumor spheroids (MTS),an in vitro system that mimics in vivo tumors,in comparison to free PTX.This increased antitumoral activity is accompanied by efficient cell internalization and increased apoptosis,especially in lung cancer MTS.Our results offer the first evidence that hollowp4VP NPs can improve the antitumoral activity of PTX.This system can be used as a new nanoplatform to overcome the limitations of current breast and lung cancer treatments.     

Facile synthesis of fully ordered L10-FePt nanoparticles with controlled Pt-shell thicknesses for electrocatalysis

We report a simple one-step approach for the synthesis of ～4 nm uniform and fully L10-ordered face-centered tetragonal (fct) FePt nanopartides (NPs) embedded in ～60 nm MCM-41 (fct-FePt NPs@MCM-41).We controlled the Pt-shell thickness of the fct-FePt NPs by treating the fct-FePt NPs@MCM-41 with acetic acid (HOAc) or hydrochloric acid (HC1) under sonication,thereby etching the surface Fe atoms of the NPs.The fct-FePt NPs deposited onto the carbon support (fct-FePt NP/C) were prepared by mixing the fct-FePt NPs@MCM-41 with carbon and subsequently removing the MCM-41 using NaOH.We also developed a facile method to synthesize acid-treated fct-FePt NP/C by using a HF solution for simultaneous surface-Fe etching and MCM-41 removal.We studied the effects of both surface-Fe etching and Pt-shell thickness on the electrocatalytic properties of fct-FePt NPs for the methanol oxidation reaction (MOR).Compared with the non-treated fct-FePt NP/C catalyst,the HOAc-treated and HCl-treated catalysts exhibit up to 34％ larger electrochemically active surface areas (ECASAs);in addition,the HCl-treated fct-FePt NP (with ～1.0 nm Pt shell)/C catalyst exhibits the highest specific activity.The HF-treated fct-FePt NP/C exhibits an ECASA almost 2 times larger than those of the other acid-treated fct-FePt NP/C catalysts and shows the highest mass activity (1,435 mA.mg~,2.3 times higher than that of the commercial Pt/C catalyst) and stability among the catalysts tested.Our findings demonstrate that the surface-Fe etching for the generation of the Pt shell on fct-FePt NPs and the Pt-shell thickness can be factors for optimizing the electrocatalysis of the MOR.     

Bimetallic Pd-Ni core-shell nanoparticles as effective catalysts for the Suzuki reaction

A simple and efficient solution-based method for the synthesis of Pd-Ni bimetallic nanoparticles （NPs） has been developed. A series of Pd-Ni bimetallic NPs were readily achieved by reduction of PdC12 and Ni（acac）2 （acac = acetyl- acetonate） in the presence of oleylamine （OAm）, oleic acid （OA） and benzyl alcohol. Furthermore, by using high-resolution transmission electron microscopy （HRTEM）, energy-dispersive spectrometry （EDS） mapping and X-ray diffraction （XRD）, we demonstrate that the as-prepared Pd-Ni bimetallic NPs have core-shell structures with a Pd-rich core and a Ni-rich shell. In addition, the as-obtained Pd-Ni bimetallic NPs with varying compositions show excellent catalytic activities in the Miyaura-Suzuki reaction. When the nickel molar percentage was 0.23 to 0.65, the conversion with the as-obtained Pd-Ni bimetallic catalysts was above 90%. It is believed that this strategy can be employed to produce a variety of other well-defined core-shell type multimetallic nanostructures.     

Sorafenib delivery nanoplatform based on superparamagnetic iron oxide nanoparticles magnetically targets hepatocellular carcinoma

Currently,sorafenib is the only systemic therapy capable of increasing overall survival of hepatocellular carcinoma patients.Unfortunately,its side effects,particularly its overall toxicity,limit the therapeutic response that can be achieved.Superparamagnetic iron oxide nanoparticles (SPIONs) are very attractive for drug delivery because they can be targeted to specific sites in the body through application of a magnetic field,thus improving intratumoral accumulation and reducing adverse effects.Here,nanoformulations based on polyethylene glycol modified phospholipid micelles,loaded with both SPIONs and sorafenib,were successfully prepared and thoroughly investigated by complementary techniques.This nanovector system provided effective drug delivery,had an average hydrodynamic diameter of about 125 nm,had good stability in aqueous medium,and allowed controlled drug loading.Magnetic analysis allowed accurate determination of the amount of SPIONs embedded in each micelle.An in vitro system was designed to test whether the SPION micelles can be efficiently held using a magnetic field under typical flow conditions found in the human liver.Human hepatocellular carcinoma (HepG2) cells were selected as an in vitro system to evaluate tumor cell targeting efficacy of the superparamagnetic micelles loaded with sorafenib.These experiments demonstrated that this delivery platform is able to enhance sorafenib's antitumor effectiveness by magnetic targeting.The magnetic nanovectors described here represent promising candidates for targeting specific hepatic tumor sites,where selective release of sorafenib can improve its efficacy and safety profile.     

Synthesis and Properties of Magnetic Nanoparticles

The uniform mesoporous SBA-15 consisting of SiO2 with long-range channels Offers an excellent host material to synthesize or assemble the magnetic nanocomposites, such as Fe, Ni. In this paper, highly dispersed and uniform iron nanoparticles were incorporated into the pore channels of SBA-15 through a newly developed strategy in which some kinds of coupling agents were used to entrap the nanoparticles into the silica framework. The X-ray diffraction （XRD）, fourier transmission infrared spectroscopy （FTIR）, high-resolution transmission electronic microscopy （HRTEM） and energy dispersive X-ray spectroscopy （EDX） were performed to further identify the successful incorporation and grafting of iron. Compared with other ordinary non-assembled magnetic nanoparticles, the assembled Fe nanoparticles with the diameter even in the size range of 5～6 nm still have better magnetic properties.     

Reaction inside a viral protein nanocage: Mineralization on a nanoparticle seed after encapsulation via self-assembly

Protein nanocages are ideal templates for the bio-inspired fabrication of nanomaterials due to several advantageous properties.During the mineralization of nanoparticles (NPs) inside protein nanocages,most studies have employed a common strategy:seed formation inside protein nanocages followed by seeded NP growth.However,the seed formation step is restricted to gentle reaction conditions to avoid damage to the protein nanocages,which may greatly limit the spectrum of seed materials used for NP growth.We put forward a simple route to circumvent such a limitation:encapsulation of a preformed NP as the seed via self-assembly,followed by the growth of an outer metal layer.Using such a method,we succeeded in mineralizing size-tunable Au NPs and Au@Ag core-shell NPs (＜10 nm in diameter) with narrow size distributions inside the virus-based NPs of simian virus 40.The present route enables the utilization of NPs synthesized under any conditions as the starting seeds for nanomaterial growth inside protein nanocages.Therefore,it potentially leads to novel bioinorganic chimeric nanomaterials with tailorable components and structures.     

Rapid Synthesis of Piezoelectric ZnO-Nanostructures for Micro Power-Generators

In this paper,we report a rapid synthesis of piezoelectric ZnO-nanostructures and fabrication of the nanostructuresbased power-generators demonstrating an energy conversion from an environmental mechanical/ultrasonic energy to an electrical energy.The ZnO nanostructures are grown on a silicon wafer by a modified chemical solution method(CSD,chemical-solution-deposition) with a two-step thermal-oxidation approach.The synthesis process can be completed within 1 h.By varying the mixture-ratio of Zn micro-particles in an oxalic acid solution with0.75 mol/l concentration in the℃SD process,the growth mechanism is well-controlled to synthesize three different types of ZnO-nanostructures(i.e.,dandelion-like nanostructures,columnar nanostructures,and nanowires).Furthermore,through oxidizing at different temperatures in the thermal-oxidation process,the featured geometry of the nanostructures(e.g.,the length and diameter of a nanowire) is modified.The geometry,size,morphology,crystallization,and material phase of the modified nanostructures are characterized by scanning electron microscopy and X-ray diffraction.Finally,the nanostructures are used to fabricate several micro power-generators.Through the piezoelectric effect,a maximum current density output of 0.28 mA cm2generated by a power-generator under an ultrasonic wave is observed.     

Thorium/uranium mixed oxide nanocrystals: Synthesis, structural characterization and magnetic properties

One of the primary aims of the actinide community within nanoscience is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects （e.g., nanocrystals） are necessary. Hence, a ＂library＂ dedicated to the preparation of various actinidebased nanoscale building blocks is currently being developed. Nanoscale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nanocrystals （both for thorium and uranium, and recently extended to neptunium and plutonium）. In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nanocrystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate （together with additional capping agents） into benzyl ether can be used to synthesize thorium/uranium mixed oxide nanocrystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium：uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nanocrystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nanocrystals of non-magnetic oxides as recently claimed in the literature.     

Magnetic Flux Alignment Studies on Entrapped Ferrofluid Nanoparticles in Poly Vinyl Alcohol Matrix

Highly surface active super paramagnetic colloidal suspensions of nano crystalline ferrofluid have been synthesized through wet-chemical route. Entrapment of magnetic domains presented in the nano ferrofluid in a polymer matrix like poly vinyl alcohol film was accomplished by developing polymer composite film in between two magnetic poles by solvent casting method. Similarly poly vinyl alcohol-ferrofluid composite films were also developed in the absence of magnetic field. Atomic force microscopy image of nano-composite film makes it clear that the film developed in the absence of magnetic field possesses randomly oriented domains, whereas film developed with magnetic field shows well aligned flux lines. The characteristics and nature of forces acting between magnetic domains along the magnetic flux lines were explored from magnetic force microscopy imaging. The number of flux lines developed in the polymer matrix was observed to be directly proportional to applied external magnetic field. Approximate number of magnetic lines passing through unit area of composite film was evaluated from line profile data analysis of atomic force microscopy image. The particle sizes of the nanoparticles encapsulated in the polymer matrix were found to be in the range of 10- 20 nm. Scanning electron microscopy micrographs confirm aggregation of ferrofluid particles of ribbon like morphology along the magnetic flux lines. Magnetic properties of the entrapped nanoparticles in polymer matrix film were analyzed using vibrating sample magnetometer at room temperature. The super paramagnetic nature and other magnetic properties were evaluated from the hysteresis loop.     

Mechanosynthesis of polymer-stabilized lead bromide perovskites: insight into the formation and phase conversion of nanoparticles

The application of polymers to replace oleylamine(OLA)and oleic acid(OA)as ligands for perovskite nanocrystals is an effective strategy to improve their stability and durability especially for the solution-based processing.Herein,we report a mechanosynthesis of lead bromide perovskite nanoparticles(NPs)stabilized by partially hydrolyzed poly(methyl methacrylate)(h-PMMA)and highmolecular-weight highly-branched poly(ethylenimine)(PEI-25K).The as-synthesized NP solutions exhibited green emission centered at 516 nm,possessing a narrow full-width at half-maximum of 17 nm and as high photoluminescence quantum yield(PL QY)as 85%,while showing excellent durability and resistance to polar solvents,e.g.,methanol.The colloids of polymer-stabilized NPs were directly processable toform stable and strongly-emitting thin films and solids,making them attractive as gain media.Furthermore,the roles of h-PMMA and PEI-25K in the grinding process were studied in depth.The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs.The PEI-25K with large amounts of amino groups induced significant enrichment of PbBr₂in the reaction mixture,which in turn caused the formation of CsPb₂Br₅-mPbBr₂and CsPbBr₃-Cs₄PbBr₆-nCsBr NPs.The presence of CsPbBr₃-Cs₄PbBr₆-nCsBr NPs was responsible for the high PL QY,as the Cs₄PbBr₆phase with a wide energy bandgap can passivate the surface defects of the CsPbBr₃phase.This work describes a direct and facile mechanosynthesis of polymer-coordinated perovskite NPs and promotes in-depth understanding of the formation and phase conversion for perovskite NPs in the grinding process.     

Synthesis of Macroscopic Zr（C6H5PO3）2 Tubes

A new method of infiltration-diffusion is used to synthesize macroscopic α-Zr（C6H5PO3）2 （α-ZrBP） tube. Compared to the routine method, no HF was used and a fiberlike product with several millimeters in length was obtained. SEM （scanning electronic microscopy） result indicates that these fibers are tubes. The wall of the tubes is composed of the flake of α-ZrBP overlapped with each other. As we know, it is the first report on the synthesis of millimeter-scale supramolecular assembly of α-ZrBP.     

Interfacial Synthesis of δ-MnO_2 Nano-sheets with a Large Surface Area and Their Application in Electrochemical Capacitors

Birnessite-type MnO_2(δ-MnO_2) nano-sheets were successfully synthesized by an interfacial synthesis method in this work.The properties and electrochemical performance of the as-prepared δ-MnO_2 were analyzed and evaluated by scanning electron microscopy(SEM),X-ray diffraction(XRD),nitrogen adsorption measurement and electrochemical tests.This facile synthesis method enables δ-MnO_2 nanosheets to show a large specific surface area(257.5 m~2 g~(-1)).The electrochemical test results show that the specific capacitance is 272 Fg~(-1) and the specific capacitance retention is over 96.7%after 1000 cycles at a scan rate of 10 mV s~(-1).All results demonstrate that δ-MnO_2 has a great potential application in highperformance electrochemical capacitors,and this interfacial synthesis method will be a very promising method to synthesize highly active MnO_2 materials in a large scale.     

Reactivity of Nanostructured MnO2 in Alkaline Medium Studied with a Microcavity Electrode: Effect of Oxidizing Agent

The synthesis of MnO2 powders by hydrothermal method with different oxidizing agents has been successfully achieved. The characterizations by scanning electron microscopy, energy-dispersive X-ray analyses, transmission electron microscopy, and X-ray diffraction techniques confirm the synthesis of nanostructured γ-MnO2 powders. The electrochemical reactivity of these powders in 1 mol/l KOH is investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) by using microcavity electrode. The results reveal that the MnO2 synthesized with Na2S2O8 shows the highest electrochemical reactivity in the test medium. This is due both to its large expanded surface area and its crystallographic variety γ-MnO2 formed in the matrix of ramsdellite, which is largely used as cathodic material for primary batteries. However, the presence of pyrolusite in the structure of γ-MnO2 synthesized with (NH4)2S2O8 decreases its electrochemical reactivity due to its narrow 1×1 size tunnel, which hinders the protons insertion.     

Facile Synthesis of Bimetallic Au@Pd Nanoparticles with Core-shell Structures on Graphene Nanosheets

In this paper, we report a simple one-step thermal reducing method for synthesis of bimetallic Au@Pd nanoparticles with core-shell structures on the graphene surface. This new type of Au@Pd-G composites is characterized by transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. It is found that Au@Pd nanoparticles with an average diameter of 11 nm are well dispersed on the graphene surface, and the Au core quantity as well as the Pd shell thickness can be quantitatively controlled by loading different amounts of metallic precursors, and the involved core-shell structure formation mechanism is also discussed. The ternary Pt/Au@Pd-G composites can also be synthetized by the subsequent Pt doping. The catalytic performance of Au@Pd-G composites toward methanol electro-oxidation in acidic media is investigated. The results show that Au@Pd-G composites exhibit higher catalytic activity, better stability and stronger tolerance to CO poisoning than Pd-G and Au-G counterparts.     

A biotechnological perspective on the application of iron oxide nanoparticles

In recent decades,magnetic iron nanoparticles (NPs) have attracted much attention due to properties such as superparamagnetism,high surface area,large surface-to-volume ratio,and easy separation under external magnetic fields.Therefore,magnetic iron oxides have potential for use in numerous applications,including magnetic resonance imaging contrast enhancement,tissue repair,immunoassay,detoxification of biological fluids,drug delivery,hyperthermia,and cell separation.This review provides an updated and integrated focus on the fabrication and characterization of suitable magnetic iron NPs for biotechnological applications.The possible perspective and some challenges in the further development of these NPs are also discussed.     

A versatile cooperative template-directed coating method to synthesize hollow and yolk-shell mesoporous zirconium titanium oxide nanospheres as catalytic reactors

The design of hollow mesoporous nanostructures for cascade catalytic reactions can inject new vitality into the development of nanostructures. In this study, we report a versatile cooperative template-directed coating method for the synthesis of hollow and yolk-shell mesoporous zirconium titanium oxide nanospheres with varying compositions （ZrO2 content from 0 to 100%）, high surface areas （465 m2·g-1） and uniform mesopores. In particular, the hexadecylamine （HDA） used in the coating procedure serves as a soft template for silica@mesostructured metal oxide core-shell nanosphere formation. By a facile solvothermal treatment route with an ammonia solution and calcination in air, the silica@mesostructured zirconium titanium oxide spheres can be converted into highly uniform hollow zirconium titanium oxide spheres. By simply replacing hard template silica nanospheres with core-shell silica nanocomposites, the synthesis approach can be further used to prepare yolk-shell mesoporous structures through the coating and etching process. The approach is similar to the preparation of mesoporous silica nanocomposites from the self-assembly of the core, the soft template cetyltrimethylammonium bromide （CTAB） and a silica precursor and can be extended as a general method to coat mesoporous zirconium titanium oxide on other commonly used hard templates （e.g., mesoporous silica spheres, mesoporous organosilica ellipsoids, polymer spheres, and carbon nanospheres）. The presence of highly permeable mesoporous channels in the zirconium titanium oxide shells has been demonstrated by the reduction of 4-nitrophenol with yolk-shell Au@mesoporous zirconium titanium oxide as the catalyst. Moreover, a cascade catalytic reaction including an acid catalyzed step and a catalytic hydrogenation to afford benzimidazole derivatives can be carried out very effectively by using the accessible acidity of the yolk-shell structured mesoporous zirconium titanium oxide spheres containing a Pd core as a bifunctional catalyst, which mak     

Structural & Magnetic Characterizations of NiLiZn Nanoferrites Synthesized by Co-precipitation Method

Synthesis of Ni0.5LixZn(0.5-x)Fe2O4 nanoparticles with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 were realized via co-precipitation method. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) measurements were performed on the samples to determine the characteristics of the crystal structures and the magnetic properties of the samples, respectively. The spinel phase structures of the samples were confirmed by XRD analysis. Patterns of decreased lattice parameter and increased crystallite size values were observed by increasing the Li concentration at longer synthesis reaction periods. Similarly, for the magnetic properties, both the saturation magnetization (Ms) and coercivity (Hc) were found to vary with increasing patterns at higher Li doping levels and longer synthesis reaction periods. The results and mechanisms concerned were discussed.     

Aluminum nanocrystals evolving from cluster to metallic state:Size tunability and spectral evidence

Sub-3 nm aluminum(Al)nanocrystal is an emerging class of nanomaterial with properties distinct to noble metal nanoclusters.The complete solution synthesis of aluminum nanoclusters was recently reported,and their photoluminescence(PL)was observed for the first time.At the moment,there exists no method to tune the size of ultrasmall aluminum nanocrystals in solution thus no knowledge on the boundary state between aluminum nanoclusters to plasmonic nanoparticles.In this work,it is demonstrated a study of size-controlled solution synthesis of ultrasmall aluminum nanocrystals with size controlled between -2.2 and -3.8 nm.Increasing the size results in three sets of spectral responses:(1)absorption due to nascent plasmons generated at -340 nm for larger particles,confirmed by Mie theory calculations;(2)significant decreased quantum yield of PL from -7.8%to -2.4%,indicating reduced quantum confinement effects and increased metallicity;(3)drop of fluorescence lifetime was observed,especially when the diameter of aluminum nanoparticles was changed from -3.0 to -3.8 nm.This study provides experimental evidence and insights to the transitional state between aluminum nanoclusters and plasmonic nanoparticles,which seems to occur at size larger than gold nanoclusters.