Synthesis of Mesoporous Yolk-Shell Magnetic Prussian Blue Particles for Multi-Functional Nanomedicine.

Mesoporous magnetic Prussian Blue (PB) particles are good condidates for theragnostic nanomedicine. However, there are lack of efficient methods for fabrication of such materials. Here, we reported the synthesis of the mesoporous yolk-shell Fe3O4@PB particles by one-pot coordination replication and etching. Time-dependent transmission electron microscopy illustrated that the PB crystals nucleated and grew on the surface of Fe3O4 spheres by coordination replication with the help of protons. The extra protons in the reaction medium further disassociated the Fe3O4 and PB, leading to mesoporous particles. The mesoporous yolk-shell Fe3O4@PB particles showed enhanced efficacy for loading cisplatin. The release of the drug molecules could be facilitated by increasing temperature. Both photo irradiation and alternating magnetic fields could trigger the release of heat from the composite. The obtained materials could delivery cisplatin to kill cancer cell intracellularly.

Rational Synthesis of Hollow Prussian Blue Analogue Through Coordination Replication and Controlled-Etching for Cs-Ion Removal.

Radioactive cesium pollution have received considerable attention due to the increasing risks in development of the nuclear power plants in the world. Although various functional porous materials are utilized to adsorb Cs+ ions in water, Prussian blue analogues (PBAs) are an impressive class of candidates because of their super affinity of Cs+ ions. The adsorption ability of the PBAs strongly relate to the mesostructure and interstitial sites. To design a hollow PBA with large number of interstitial sites, the traditional hollowing methods are not suitable owing to the difficulty in processing the specific PBAs with large number of interstitial sites. In this work, we empolyed a rational strategy which was to form a "metal oxide"@"PBA" core-shell structure via coordination replication at first, then utilized a mild etching to remove the metal oxide core, led to hollow PBA finally. The obtained hollow PBAs were of high crystallinity and large number of interstitial sites, showing a super adsorption performance for Cs+ ions (221.6 mg/g) within a short period (10 min).

Hollow carbon nanobubbles: monocrystalline MOF nanobubbles and their pyrolysis.

While bulk-sized metal-organic frameworks (MOFs) face limits to their utilization in various research fields such as energy storage applications, nanoarchitectonics is believed to be a possible solution. It is highly challenging to realize MOF nanobubbles with monocrystalline frameworks. By a spatially controlled etching approach, here, we can achieve the synthesis of zeolitic imidazolate framework (ZIF-8) nanobubbles with a uniform size of less than 100 nm. Interestingly, the ZIF-8 nanobubbles possess a monocrystalline nanoshell with a thickness of around 10 nm. Under optimal pyrolytic conditions, the ZIF-8 nanobubbles can be converted into hollow carbon nanobubbles while keeping their original shapes. The structure of the nanobubble enhances the fast Na+/K+ ion intercalation performance. Such remarkable improvement cannot be realized by conventional MOFs or their derived carbons.

Spontaneous Weaving of Graphitic Carbon Networks Synthesized by Pyrolysis of ZIF-67 Crystals.

Three-dimensional (3D) networks of graphitic carbon are promising materials for energy storage and conversion devices because of their high electrical conductivity, which is promoted by the good interconnection between the carbon particles. However, it is still difficult to directly synthesize such carbon networks. Herein, we report the novel synthesis of 3D graphitic carbon networks through the pyrolysis of nanosized ZIF-67 crystals. Interestingly, the unusual effect of downsizing the ZIF-67 crystals and the incorporation of catalytic Co nanoparticles was the spontaneous formation of graphitic networks. The obtained graphitic carbon networks show excellent electrochemical performance for the insertion and extraction of potassium ions.

Coordination Polymer Nanoglue: Robust Adhesion Based on Collective Lamellar Stacking of Nanoplates.

Despite a continuously growing interest in the integration of coordination polymer (CP) colloids toward functional materials, collective properties of the CP colloids have rarely been addressed mainly due to the difficulty in assembling pure CP colloids into superstructures with impressive mechanical strength. We demonstrated that CP nanoplates could stack together spontaneously upon drying the slurry of the nanoplates. The stacked CP nanoplates could work like polymeric adhesives. Versatile articles could be glued when the CP nanoplates were sandwiched between two substrates. In addition, the CP nanoplates themselves could form well-defined bulk structures without using any additional adhesives. The anisotropic shape together with the lamellar stacking way of the CP nanoplates were found to be the key points in leading to the adhesion and cohesion effect. The reasonable adhesion strength of the CP nanoglues can allow the exploration of further applications of integrated CP colloids in the future.

Synthesis of Monocrystalline Nanoframes of Prussian Blue Analogues by Controlled Preferential Etching.

Metal cyanide coordination compounds are recognized as promising candidates for broad applications because of their tailorable and adjustable frameworks. Developing the nanostructure of a coordination compound may be an effective way to enhance the performance of that material in application-based roles. A controllable preferential etching method is described for synthesis of monocrystalline Prussian blue analogue (PBA) nanoframes, without the use of organic additives. The PBA nanoframes show remarkable rate performance and cycling stability for sodium/lithium ion insertion/extraction.

Mesocrystalline coordination polymer as a promising cathode for sodium-ion batteries.

Prussian blue (PB) mesocrystals with Na as the alkaline metal were synthesized and used as cathode materials in Na-ion batteries. The mesocrystalline structure endowed PB with very different phase change behavior and electrochemical performance in contrast to PB single-crystals in cyclic voltammograms and galvanostatic discharge/charge voltage profiles of PB/Na half-cells.

Three-dimensional hierarchical Prussian blue composed of ultrathin nanosheets: enhanced hetero-catalytic and adsorption properties.

Three-dimensional hierarchical Prussian blue composed of ultrathin nanosheets was successfully synthesized by employing a self-aggregation and oriented attachment strategy. The unique structure highly increases the exposure of micropores and metal sites of Prussian blue to guests, thus significantly enhancing its hetero-catalysis and adsorption properties compared to cubic and commercial counterparts.

Synthesis, Characterization and Adsorption Properties of Magnetic γ-Fe2O3/C Nanocomposite.

γ-Fe2O3/C nanocomposite was prepared through a convenient method by which one-pot synthesized Fe3O4/Starch was oxidized and carbonized by calcining at 250 °C. The γ-Fe2O3/C displayed strong magnetism and could adsorb organic molecules from aqueous solution effectively, thus it showed promising application in the dislodgement of organic pollutants in sewage. Adsorption isotherms and kinetics of methylene blue (MB) onto γ-Fe2O3/C were studied in a batch system. The adsorption process reached equilibrium in about 15 min, and the maximum adsorption capacity of MB was found to be 64.9 mg g-1 at 303 K. Adsorption isotherms were well fitted to Langmuir model and the adsorption kinetics could be described by the pseudo-second order kinetic equation. The findings of the present work highlight a new facile method to fabricate magnetic carbon-based composites and the obtained γ-Fe2O3/C with excellent magnetic property and adsorption performance hold great promise for practical application in water treatment.

A versatile strategy to construct multifunctional metal oxide@cyanometallate-based coordination polymer heterostructures.

We have developed one versatile spatially confined self-assembly strategy to integrate cyanometallate-based coordination polymers with functional metal oxides into well-defined core@shell heterostructures. The structure, composition, size and morphology of the heterostructures could be facilely controlled. The obtained Fe3O4@Prussian blue heterostructure was evaluated as an appealing multifunctional thermal ablation agent exhibiting response to both magnetic field and light irradiation.

Three-dimensionalization of ultrathin nanosheets in a two-dimensional nano-reactor: macroporous CuO microstructures with enhanced cycling performance.

Three-dimensional (3D) macroporous CuO structures composed of ultrathin nanosheets were successfully synthesized by employing a liquid-liquid interface as a two-dimensional (2D) nano-reactor. The macroporous structure helped CuO to retain the exposed surface during reactions, thus significantly enhancing the long term cycling performance both in photocatalysis and lithium ion batteries.

HF-free synthesis of anatase TiO2 nanosheets with largely exposed and clean {001} facets and their enhanced rate performance as anodes of lithium-ion battery.

An interface between toluene and water was utilized to synthesize ca. 10 nm thick of anatase TiO2 nanosheets (NSs) with 82% exposure of {001} facets. In this procedure, highly corrosive and toxic HF, which was generally used to prepare TiO2 NSs with largely exposed high energy facets, was avoided. Furthermore, the surfaces of the NSs were quite clean as suggested by XPS analysis. Serving as anode materials in lithium-ion batteries, these as-prepared anatase TiO2 NSs manifested a low initial irreversible capacity loss (12.5% at 1 C), an excellent capacity retention at 10 C charge-discharge rate (101.9 mA h g(-1) after 100 cycles), and enhanced rate performance at 0.5-10 C current rates in compared with Degussa P25 TiO2 nanoparticles (NPs). Their excellent electrochemical performances were mainly derived from the large proportion of {001} exposed facets and a very short diffusion pathway, which allowed fast and efficient Li(+) transportation in the electrodes.

Monocrystalline mesoporous metal oxide with perovskite structure: a facile solid-state transformation of a coordination polymer.

Monocrystalline mesoporous BiFeO3 crystals were obtained via a multi-step single-crystal to single-crystal transformation of a coordination polymer, Bi[Fe(CN)6]·4H2O. This unique transformation process significantly decreased the crystallization temperature of perovskite oxide without losing high crystallinity.

Coordination polymers for catalysis: enhancement of catalytic activity through hierarchical structuring.

We utilized a novel strategy, hierarchical structuring, to enhance the catalytic activity of coordination polymers. Hierarchical Prussian white crystals with hollow structures and kinked surfaces were synthesized by using a self-aggregation and etching strategy. The hierarchical structure significantly enhanced the catalytic activity of Prussian white in the degradation of methylene blue in comparison to the non-hierarchical Prussian white crystals.

One-step hydrothermal synthesis of Fe3O4@C nanoparticles with great performance in biomedicine.

Core-shell structured Fe3O4@C nanoparticles were fabricated by a facile one-pot hydrothermal route. The structure and component of the nanoparticles were fully characterized by transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy, Raman spectroscopy, thermogravimetric analysis, magnetometry and Brunauer-Emmett-Teller specific surface area measurements. The obtained Fe3O4@C nanoparticles possessed favorable dispersibility, high saturation magnetization (61.4 emu g-1) that could quickly respond to external magnetic field and excellent biocompatibility. Excitingly, the experiments of the Fe3O4@C nanoparticles as drug carriers revealed an efficient drug-loading as high as 1.08 mg mg-1. More importantly, the drug loading composite exhibited pH-responsive release profiles and the duration was as long as 200 h; at the pH value of 5.8 and 7.4, the release rate was 93.7% and 33.6%, respectively. Furthermore, the obtained Fe3O4@C nanoparticles had good magneto-thermal ability. All these positive attributes make the as-prepared Fe3O4@C nanoparticles a promising platform for further biomedical evaluations.

Nanofluids Containing γ-Fe2O3 Nanoparticles and Their Heat Transfer Enhancements.

Homogeneous and stable magnetic nanofluids containing γ-Fe2O3 nanoparticles were prepared using a two-step method, and their thermal transport properties were investigated. Thermal conductivities of the nanofluids were measured to be higher than that of base fluid, and the enhanced values increase with the volume fraction of the nanoparticles. Viscosity measurements showed that the nanofluids demonstrated Newtonian behavior and the viscosity of the nanofluids depended strongly on the tested temperatures and the nanoparticles loadings. Convective heat transfer coefficients tested in a laminar flow showed that the coefficients increased with the augment of Reynolds number and the volume fraction.

Prussian blue microcrystals prepared by selective etching and their conversion to mesoporous magnetic iron(III) oxides.

A new morphology of Prussian blue microcrystals has been prepared by selective etching. By thermal decomposition, PB has been transformed into mesoporous magnetic iron(III) oxide.

Preparation and properties of a novel drug delivery system with both magnetic and biomolecular targeting.

By loading doxorubicin (DOX) on 5-carboxyl-fluorescein (FAM) labeled AGKGTPSLETTP peptide (A54) coupled starch-coated iron oxide nanoparticles (SIONs), we prepared a novel aqueous drug delivery system with both magnetic and biomolecular targeting, which was specific to human hepatocellular carcinoma cell line BEL-7402. The saturated extent of adsorption reached 2.0 mg DOX/mg A54-SIONs at 28 degrees C, which provided a rather high dose of DOX loading for application. Tests in vitro demonstrated the specificity of DOX-loaded A54-SIONs to BEL-7402 cells. The microscopy images proved that DOX-loaded A54-SIONs were successfully targeted to tumor tissue of nude mice with an external magnetic field in vivo. MTT assay showed higher cytostatic effect of DOX-loaded A54-SIONs to hepatocellular carcinoma cells BEL-7402 than that of DOX-loaded SIONs.

Preparation of Fe3O4Spherical Nanoporous Particles Facilitated by Polyethylene Glycol 4000.

Much interest has been attracted to the magnetic materials with porous structure because of their unique properties and potential applications. In this report, Fe3O4nanoporous particles assembled from small Fe3O4nanoparticles have been prepared by thermal decomposition of iron acetylacetonate in the presence of polyethylene glycol 4000. The size of the spherical nanoporous particles is 100-200 nm. Surface area measurement shows that these Fe3O4nanoporous particles have a high surface area of 87.5 m2/g. Magnetization measurement and Mössbauer spectrum indicate that these particles are nearly superparamagnetic at room temperature. It is found that the morphology of the products is greatly influenced by polyethylene glycol concentration and the polymerization degree of polyethylene glycol. Polyethylene glycol molecules are believed to facilitate the formation of the spherical assembly.

Immobilization of homing peptide on magnetite nanoparticles and its specificity in vitro.

As a homing peptide, A54 is the most effective peptide specific to the human hepatocellular carcinoma cell. Homing peptide labeled with green fluorescent protein (A54-GFP) was successfully immobilized on the surfaces of magnetic nanoparticles and characterized by Fourier transform infrared spectroscopy as well as fluorescence microscopy. The binding efficiency was analyzed by performing adsorption equilibrium and SDS-PAGE electrophoresis. Specific binding of the nanoparticles functionalized with A54-GFP to human hepatocellular carcinoma cells in vitro was visualized using fluorescence microscopy. The results demonstrated the specificity of A54-GFP-coated magnetic nanoparticle to tumor cell, pointing to its great potential in magnetic cell separation and purification, magnetic resonance imaging (MRI), magnetic hyperthermia, and drug targeting.