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In this report, a continuous stirring tank reactor (CSTR) and batch reactor were used for synthesis of silver (Ag) plates. The influences of agitation speed, molar ratio of AgNO3 to NaCl, and concentration of reagent were investigated. Size analysis demonstrated that the size of Ag plates synthesized by the CSTR was larger than the size of plates synthesized by the batch reactor. The reason might be that low concentration of reagent and continuous supply of monomer in CSTR are more favorable for growth of anisotropic structures. CSTR demonstrates good advantages for mass synthesis of Ag plates of large size.

We introduce a promising protocol that can be used to fabricate polymer particles with a high degree of shape anisotropy; this method can be utilized with a variety of microfluidic generation methods. Low-density microparticles and high-density nanoparticles vertically migrated in a polymer solution confined in emulsion droplets that were produced via a microfluidic method. As the solvent evaporated in individual droplets at ambient conditions, the low-density microparticles migrated upward because their density was lower than that of the polymer solution. The high-density nanoparticles that were initially well-dispersed in the droplet phase became destabilized upon solvent removal, leading to the formation of aggregates and sedimentation in a downward direction. The migration of the particle components during solvent evaporation induced shape deformation/modification of the emulsion droplets; consequently, polymer particles with highly anisotropic shapes were created after drying.

A customized droplet-based microfluidic reactor was fabricated for the synthesis of silver nanoparticles (Ag NPs) using silver nitrate (AgNO3) and branched polyethyleneimine (BPEI) as a precursor and a reducing agent, respectively. The effects of static mixing, temperature, and the volumetric flow rates of AgNO3 and BPEI on the particle size were investigated. The use of a static mixer and the optimization of the reaction temperature enhanced the monodispersity of the Ag NPs. In addition, the size of the Ag NPs was manipulated by changing the flow rate ratio of AgNO3 to BPEI at 60 °C for 60 min.

Spherical mesoporous γ-Al2O3 (γ-Al) particles, embedded with magnetite nanoparticles (MNPs), were successfully prepared using a novel approach combining sol-gel and spray pyrolysis methods. Due to the magnetism of the embedded MNPs, the MNP/γ-Al particles can be utilized as recyclable catalyst supports. To demonstrate their recovery efficacy, Pd nanoparticles were impregnated on the surface of the MNP/γ-Al particles using the wetness impregnation method, and the resulting Pd/MNP/γ-Al catalysts were used to catalyze hydrogenation reactions of 4-nitrophenol. We demonstrated that when the magnetic nanoparticles were embedded in the catalysts, the recovery efficiency of the catalysts was further improved under the magnetic field.

We successfully synthesized metal hydroxide (Ni(OH)2 and Co(OH)2) nanoplates and platinum/nickel hydroxide hybrid nanostructures (Pt/Ni(OH)2) in an aqueous solution. Transmission electron microscopy studies of the Pt/Ni(OH)2 hybrid nanostructures revealed that a number of 3 nm-sized Pt nanoparticles were well dispersed on the surface of each Ni(OH)2 nanoplate. The Pt/Ni(OH)2 hybrid nanostructures exhibited enhanced electrocatalytic properties due to synergetic effect of Ni(OH)2 and Pt.

We reported on an aqueous-phase synthesis of copper-palladium (Cu-Pd) nanoplates consisting of 5 nm-sized Pd nanoparticles deposited on Cu nanoplates. In the present synthesis, ascorbic acid was used as a reducing agent to prevent galvanic replacement. By controlling the experimental conditions, we could control the weight percent of Pd in the nanoplates from 0.56% to 2.02%. The Cu-Pd nanoplates with Pd content of 2.02% exhibited high catalytic performance in the direct H2O2 generation reaction.

Synthesis of magnetite nanocrystals typically requires harsh reaction conditions, including high reaction pressures and/or temperatures, to obtain morphology-controlled nanocrystals like cubic magnetite nanocrystals. We report the synthesis of cubic magnetite nanocrystals with a size of 9 nm at reaction temperatures less than 100 °C in air. The synthesized magnetite nanocubes exhibited uniform size and highly crystalline nature. In addition, we synthesized size-controlled spherical magnetite nanocrystals in the size range of 2.5 nm to 9 nm by modifying the reaction conditions.

We report the external field-guided shape transformation of magnetite-polymer composite particles that play multiple roles in heterogeneous chemical reactions, such as catalysts, catalyst supports, and micro-stirrers. A microfluidic method was used to generate monodispersed emulsion droplets composed of polystyrene, magnetite nanoparticles (MNPs), and chloroform. While the solvent in the droplets was dried in the presence of an external magnetic field, the emulsion droplets were deformed or elongated along the field direction, consequently leading to magnetically responsive particles with anisotropic shape after complete removal of the solvent. Coarse-grained molecular dynamic simulations demonstrated that the shape deformation was due to destabilization of the MNPs upon solvent drying and migration of the aggregated MNPs in the polymer matrix along the external field. The particle shape could be readily tunable by modulating the field strength and direction as well as the concentrations of the MNPs and polymer. We further revealed that these magnetic anisotropic particles coated with palladium nanoparticles could be used as catalysts, catalyst supports, micro-stirrers when the particles were dispersed in a small confined volume of a catalytic precursor solution.

The efficiency of two prototype catalysis systems using palladium (Pd)-coated microparticles was investigated with regard to the recovery and recyclability of the catalytic particles. One such system was the interface-adsorption method, in which polymer particles coated with Pd nanoparticles strongly and irreversibly attach to the oil-water interface. Due to the irreversible adsorption of the catalytic particles to the interface, particle loss was completely prevented while mixing the aqueous solution and while collecting the products. The other system was based on the magnetic field-associated particle recovery method. The use of polymeric microparticles containing Pd nanoparticles and magnetite nanoparticles accelerated the sedimentation of the particles in the aqueous phase by applying a strong magnetic field, consequently suppressing drainage of the particles from the reactor along the product stream. Upon multiple runs of the catalytic reactions, it was found that conversion does not change significantly, demonstrating the excellent recyclability and performance efficiency in the catalytic processes.

As a joint investigation principle using experimental and theoretical approaches, we report that the anisotropic growth of Pt on Pd nanocubes significantly promotes the direct synthesis of hydrogen peroxide (H2O2) from hydrogen (H2) and oxygen (O2). The superior H2O2 productivity of the anisotropic Pd@Pt core@shell nanocrystals results from the enhanced H2 conversion and the H2O2 selectivity compared to Pd and Pt. From the joint investigation, during the anisotropic growth of the Pd@Pt nanocrystals, high-index facets such as (2 1 0) are generated, and they provide numerous active sites for hydrogen dissociation. Notably, even the nano-catalyst is enclosed by Pt shell, the high-index facets are favorable for opening a new route for hydrogen dissolution into the Pd bulk lattices of the Pd@Pt nanocrystals, in which the dissolved hydrogen can react with chemisorbed O2 over the nanocrystals to form H2O2. This mechanism is suggested by a hydrogen temperature programmed reduction (H2-TPR) analysis, in situ transmission electron microscopy (TEM), and density functional theory (DFT) calculations. This study provides another option to improve the catalytic performance of core@shell nanocrystals via the generation of high-index facets through anisotropic growth of nanocrystals, in addition to the well-known strain and charge transfer effects. We expect that the anisotropic growth approach could be extended to other catalytic reactions.

Metal and oxide nanoparticles (NPs) are attracting extensive attention in biomedical applications, including bioimaging and drug delivery. However, it is difficult to use these NPs as therapeutic agents for specific cell and tissue treatments because of limitations such as material oxidization and cell toxicity. Herein, we synthesized Cu-based angiogenic metal nanoparticles (Cu-AMNs), using a galvanic replacement reaction of Cu NPs and Au precursor, which stabilized and upregulated intracellular behaviors in human adipose-derived stem cells (hADSCs). Our novel therapeutic Cu-AMNs showed remarkable advantages in cell treatment, such as low mitochondrial damage, reduced ATP consumption, decreased cytotoxicity, mild reactive oxygen species generation with enhanced angiogenic paracrine factor secretion, and improved hypoxia inducible factor-1 alpha (HIF-1α) expression. Through the improved expression of HIF-1α, vascular endothelial growth factor (VEGF) secretion was prolonged for 3 days, even in re-attached hADSCs. In addition, Cu-AMNs improved other angiogenic factors and the amount of exocytosed Cu from hADSCs, resulting in strong development of tubular formation by human umbilical vein endothelial cells in vitro. Finally, transplantation of Cu-AMN-treated hADSCs in mice led to a significant in vivo increase in angiogenesis and blood perfusion in a mouse hindlimb ischemia model compared with conventional hADSC therapy.

Electrochemical activity and stability depend on the composition and morphology of nanocrystals. Mn3O4 nanoplates, Mn2O3 nanoplates, and porous Mn2O3 nanoplates were synthesized by heat treatment of Mn-glycolate nanoplates prepared by the wet-chemical method. In this research, the morphology and composition of the nanoplates could be easily controlled by varying the annealing temperature. The synthesized porous Mn2O3 nanoplates exhibited better electrocatalytic activities compared with Mn3O4 and Mn2O3 nanoplates, as similar as commercial IrO2 catalyst.

Uniform silica particles were synthesized by synergistic combination of sodium 4-styrene sulfonate (NaSS) anionic surfactant and organic amine base catalyst such as ethylenediamine (EDA) or diethylenetriamine (DETA). The EDA and DETA organic amine base catalysts could promote the growth reaction rate so that they produced larger silica particles compared to the NH4OH base catalyst because the organic amines provide more basic micro-environment near the surface of the silica particle due to multiple amine groups in a single molecule. Accordingly, the size of the silica particle was 450 ± 12 nm (NH4OH), 725 ± 21 nm (EDA), and 942 ± 130 nm (DETA) in similar pH conditions.

In the synthesis of nanoparticles, the reaction rate is important to determine the morphology of nanoparticles. We investigated morphology evolution of Cu nanoparticles in this two different reactors, microemulsion reactor and batch reactor. In comparison with the batch reactor system, the enhanced mass and heat transfers in the emulsion system likely led to the relatively short nucleation time and the highly homogeneous environment in the reaction mixture, resulting in suppressing one or two dimensional growth of the nanoparticles. We believe that this work can offer a good model system to quantitatively understand the crystal growth mechanism that depends strongly on the local monomer concentration, the efficiency of heat transfer, and the relative contribution of the counter ions (Br− and Cl−) as capping agents.

We report a facile aqueous-phase synthetic route to vine-like copper sulfide (CuS) nanofibers prepared by reacting elemental sulfur with Cu+-branched polyethyleneimine (BPEI) complex obtained by the reaction of Cu2+ with ascorbic acid in the presence of BPEI. By controlling the concentration of BPEI, we could easily control the morphology of CuS from nanofibers to hollow nanoparticles. We also found that concentration of BPEI and the presence of halide anion would play important roles in the formation of vine-like CuS nanofibers.

A Couette-Taylor crystallizer is developed to enhance the l -Lysine crystal size distribution and recovery in the case of continuous cooling crystallization. When using the proposed Couette-Taylor (CT) crystallizer, the size distribution and crystal product recovery were much narrower and higher, respectively, than those from a conventional stirred tank (ST) crystallizer. Here, the coefficient of the size distribution for the crystal product from the CT crystallizer was only 0.45, while it was 0.78 in the case of the conventional ST crystallizer at an agitation speed of 700 rpm, mean residence time of 20 min, and feed concentration of 900 (g/L). Furthermore, when using the CT crystallizer, the crystal product recovery was remarkably enhanced up to 100%wt with a mean residence time of only 20 min, while it required a mean residence time of at least 60 min when using the conventional ST crystallizer. This result indicates that the CT crystallizer was much more effective than the conventional ST crystallizer in terms of controlling a narrower size distribution and achieving a 100%wt l -lysine crystal product recovery from continuous cooling crystallization. The advantage of the CT crystallizer over the conventional ST crystallizer was explained based on the higher energy dissipation of the Taylor vortex flow and larger surface area for heat transfer of the CT crystallizer. Here, the energy dissipation of the Taylor vortex flow in the CT crystallizer was 13.6 times higher than that of the random fluid motion in the conventional ST crystallizer, while the surface area per unit volume for heat transfer of the CT crystallizer was 8.0 times higher than that of the conventional ST crystallizer. As a result, the mixing condition and heat transfer of the CT crystallizer were much more effective than those of the conventional ST crystallizer for the cooling crystallization of l -lysine, thereby enhancing the l -lysine crystal size distribution and product recovery.

We could synthesize the Ag nanocubes highly reproducibly by conducting the polyol synthesis using HCl etchant in dark condition because the photodecomposition/photoreduction of AgCl nanoparticles formed at initial reaction stage were greatly depressed and consequently the selective self-nucleation of Ag single crystals and their selective growth reaction could be promoted. Whereas the reproducibility of the formation of Ag nanocubes were very poor when we synthesize the Ag nanocubes in light condition due to the photoreduction of AgCl to Ag.

The authors describe a material for the sensitive and selective voltammetric determination of mercury(II). Core-shell nanoparticles (NPs) of the type Ag@Au were prepared and modified with an oligoner with the sequence 5′-CCC CCC CCC CCC TTC TTT CTT CCC CTT GTT TGT T-3′. The NPs were characterized by transmission electron microscopy, UV-vis spectroscopy and electrochemical impedance spectroscopy. The modified NPs were examined by cyclic voltammetry (CV) and square wave voltammetry (SWV). It is shown that the material, if placed on a screen printed carbon electrode, is a viable sensor for Hg(II). If operated at a voltage as low as 10 mV (vs Ag/AgCl), it has a linear response that convers the 10 to 160 pM concentration range and a 6 pM detection limit (at an S/N ratio of 3). The sensor is rapid, convenient, inexpensive and selective. It was applied successfully to the determination of Hg(II) in spiked wastewater samples. Its low working potential makes it a highly attractive sensing tool that is not readily interfered by other redox-active species.

Here, we report that Fe ions delivered into human mesenchymal stem cells (hMSCs) by bioreducible metal nanoparticles (NPs) enhance their angiogenic and cell-homing efficacy by controlling ion-triggered intracellular reactive oxygen species (ROS) and improve cell migration, while reducing cytotoxicity. Endosome-triggered iron-ion-releasing nanoparticles (ETIN) were designed to be low-pH responsive to take advantage of the low-pH conditions (4-5) of endosomes for in situ iron-ion release. Due to the different redox potentials of Fe and Au, only Fe could be ionized and released from our novel ETIN, while Au remained intact after ETIN endocytosis. Treatment with an optimal amount of ETIN led to a mild increase in intracellular ROS levels in hMSCs, which enhanced the expression of HIF-1α, a key trigger for angiogenic growth factor secretion from hMSCs. Treatmetn of hMSCs with ETIN significantly enhanced the expression of angiogenesis- and lesion-targeting-related genes and proteins. Transplantation of ETIN-treated hMSCs significantly enhanced angiogenesis and tissue regeneration in a wound-closing mouse model compared with those in untreated mice and mice that underwent conventional hMSC transplantation.

Multi-metallic nanoparticles continue to attract attention, due to their great potential in various applications. In this paper, we report a facile aqueous-phase synthesis for multi-metallic nanoparticles, including AgPt, AgPd, CuPt, and AgCuPt, by a co-reduction method within a short reaction time of 10 min. The atomic ratio of bimetallic nanoparticles was easily controlled by varying the ratio of each precursor. In addition, we found that AgCuPt trimetallic nanoparticles had a core-shell structure with an Ag core and CuPt shell.

Additional file 1: Additional experiment.

Pd@Pt core–shell nanocubes with a partially covered Pt shell on the Pd nanocubes were synthesized by a direct seed-mediated growth method without a washing process. The FAO activity of Pd@Pt 0.4 at% was 4.3 times and 2.2 times higher than that of Pd cubes and commercial Pt/C, respectively.

Injecting human mesenchymal stem cells (hMSCs) at wound sites is known to have a therapeutic effect, however, hMSCs have several limitations, such as low viability and poor engraftment after injection, as well as a potential risk of oncogenesis. The use of a conditioned medium (CM) was suggested as an alternative method for treating various wounds instead of direct hMSC administration. In addition to not having the adverse effects associated with hMSCs, a CM can be easily mass produced and can be stored for long-term, thereby making it useful for clinical applications. In general, a CM is collected from hMSCs with low passage number, whereas, the hMSCs with high passage number are usually discarded because of their low therapeutic efficacy as a result of reduced angiogenic factor secretion. Herein, we used a CM collected from high passage number (passage 12, P12) hMSCs treated with gold-iron nanoparticles (AuFe NPs). Our AuFe NPs were designed to release the iron ion intracellularly via endocytosis. Endosomes with low pH can dissolve iron from AuFe NPs, and thus, the intracellularly released iron ions up-regulate the hypoxia-inducible factor 1&alpha, and vascular endothelial growth factor (VEGF) expression. Through this mechanism, AuFe NPs improve the amount of VEGF expression from P12 hMSCs so that it is comparable to the amount of VEGF expression from low passage number (passage 6, P6), without treatment. Furthermore, we injected the CM retrieved from P12 MSCs treated with AuFe NPs in the mouse skin wound model (AuFe P12 group). AuFe P12 group revealed significantly enhanced angiogenesis in the mouse skin wound model compared to the high passage hMSC CM-injected group. Moreover, the result from the AuFe P12 group was similar to that of the low passage hMSC CM-injected group. Both the AuFe P12 group and low passage hMSC CM-injected group presented significantly enhanced re-epithelization, angiogenesis, and tissue remodeling compared to the high passage hMSC CM-injected group. This study reveals a new strategy for tissue regeneration based on CM injection without considering the high cell passage count.

Despite its effectiveness in improving the properties of materials, strain engineering has not yet been employed to endow catalytic characteristics to apparently nonactive metals. This limitation can be overcome by controlling simultaneously lattice strains and charge transfer originated from the epitaxially prepared bimetallic core-shell structure. Here, we report the experimental results of the direct H

Residual elastic strains imposed on atomically thin films coated onto substrate materials cause changes in the electronic structures of such films. This knowledge has been employed in various industrial sectors as a means of tuning the optical, electrical, magnetic, and chemical properties of materials. Although the magnitudes of residual strains and properties of materials are closely related to the thickness of coating layers, the measurement of residual strains that develop in atomically thin films is challenging owing to the experimental complexities of conventional measurement methods. In this work, the residual strains developed in atomically thin Au overlayers grown epitaxially on Pd nanoparticles were measured using transmission electron microscopy based on nanobeam precession electron diffraction. Experiments revealed that a 1-nm-thick Au film can withstand an exceptionally high compressive strain of 4.3%, which is reduced to nearly zero as the film thickness increases beyond 5 nm. The microstructural evolution of Au films was monitored using high-resolution transmission electron microscopy and the large strain storage capacity and plastic relaxation behavior of Au films were interpreted by comparing them with the previous computer simulations and theoretical models.

We describe a facile synthetic route to α-Co(OH)2 nanostructures by heating a solution containing CoCl2, ethylene glycol, and oleylamine. Electron microscopy and X-ray diffraction analyses revealed that flower-like nanostructures of α-Co(OH)2 were formed by assembly of thin α-Co(OH)2 nanosheets. These nanostructures exhibited high activity for electrochemical water splitting with a current density comparable to that obtained on the commercial Pt wire electrode. In addition, these flower-like α-Co(OH)2 nanostructures showed specific capacitance as high as 440 F/g at a current density of 1 A/g and excellent stability without any noticeable loss in capacitance after 5000 cycles of the galvanostatic charge–discharge test.

This work describes a simple aqueous-phase synthesis of single-crystal ZnO nanobolts with sizes of 250 nm by reacting Zn(NO 3 ) 2 with octylamine. The synthesized ZnO nanobolts exhibit a hierarchical structure consisting of two well-defined hexagonal nanorods of different sizes. In a study of the growth behavior of the ZnO nanobolts, we observed that aggregates of around 600 nm in size became single-crystal ZnO nanobolts with sizes of 250 nm. We also investigated the influence of reaction temperature and Zn(NO 3 ) 2 concentration on the synthesis, demonstrating that these experimental factors were critical in terms of the size, morphology, and aggregation of ZnO nanobolts.

One of the challenges of using nanoparticles as catalysts is the presence of reaction-disturbing stabilizers that surround the nanoparticle surface. In this report, we demonstrate a method to synthesize stabilizer-free bismuth oxychloride (BiOCl) nanoparticles to increase photocatalytic activity. This synthesis method is remarkably simple, involving only BiCl3 and deionized water. After heating an aqueous solution containing BiCl3, plate-shaped BiOCl nanoparticles were formed. The stabilizer-free BiOCl nanoplates exhibited higher photocatalytic activities compared to polyvinylpyrrolidone- and polyethyleneimine-stabilized nanoplates for the degradation of methylene blue.

A continuous and defect-free ZIF-8 membrane was successfully grown on a positive surface curvature of a porous tubular alumina support that was prepared from zinc nitrate precursor solution at 120 °C for 4 h of synthesis time. The membrane produced the highest propylene permeation of 198 × 10−10 mol⋅m−2⋅s−1⋅Pa−1 and moderate separation factor of 48. Despite its modest level of separation factor, the membrane was able to enrich propylene from 50 vol%. to 98 vol% from a binary feed mixture containing equal flowrate of propylene and propane. The high purity however came with low propylene recovery of merely 5% because there was a trade-off between the separation factor and permeance as a result of an inversed relationship between the two.

The synthesis of Pd@Pt core&ndash, shell nanocubes was achieved through a direct seed-mediated growth method. This process represents a simple and cost-effective way to produce core&ndash, shell nanocubes. The morphology of the Pd@Pt core&ndash, shell nanocubes varied from simple cubic to concave cubic, depending on the reducing agent and the Pt content. The selection of the reducing agent is important because the reduction rate is directly related to the shell growth. The catalytic activity and stability of the Pd@Pt core&ndash, shell nanocubes in the methanol oxidation reaction were different for the nanocubes with partial and full Pt shells.

Additional file 1: Figure S1. (a) size distribution of nanoparticles, (b) XRD patterns of synthesized Cu-Ag-Pt-Pd nanoparticles. Figure S2. UV-vis spectrum of prepared Ag-Cu bimetallic nanoparticles. Table S1. ICP data of Cu-Ag-Pt-Pd nanoparticles.

Transition metal layered double hydroxide (LDH) nanomaterials have been considered as good catalytic materials for various applications; however, there has been a limit in the economic efficiency and convenience of the synthetic method. In this work, we report a facile aqueous-phase route to the synthesis of transition metal LDH nanoplates including Mn-Ni and Zn-Ni. Electrochemical characterization of the synthesized Mn-Ni LDHs with different intercalated halogen anions was carried out for the oxygen evolution reaction (OER) and a Tafel slope of about 80 mV per decade was obtained which is comparable to those of the previously reported LDH nanoplates.

The catalytic properties of materials are determined by their electronic structures, which are based on the arrangement of atoms. Using precise calculations, synthesis, analysis, and catalytic activity studies, we demonstrate that changing the lattice constant of a material can modify its electronic structure and therefore its catalytic activity. Pd/Au core/shell nanocubes with a thin Au shell thickness of 1 nm exhibit high H

Facile synthesis and electrochemical performance of a Co3O4 nanoparticles/porous carbon composite used as an anode in Li-ion batteries is reported in this work. Co3O4 nanoparticles (5-10 nm in size) were embedded in a disordered porous carbon network using a simple template-free chemical method. The synthesized composite work well as an anode material for Li-ion batteries by delivering stable cycle life and highly reversible capacities of 480 mAhg-1 at 500mAg-1, which is higher than that of commercially available graphite electrodes and is comparable to values reported for Co3O4/graphene composites.

We investigated the effect of Fe3O4 nanoparticle orientation on the magnetic properties of hybrid polymer nanocomposite thin films. A multilayer thin film consisting of alternating layers of polymers and assembled iron oxide nanoparticles was prepared by spin coating and Langmuir–Blodgett techniques. Transmission electron microscopy and neutron reflectivity measurements were employed to determine structural information related to the lateral orientation of the Fe3O4 nanoparticle monolayer and the layered architecture along the depth of the multilayer, respectively. The magnetic properties of the hybrid multilayer were characterized by SQUID magnetometry and compared with the properties of a spin-coated polymer nanocomposite thin film containing homogenously dispersed Fe3O4 nanoparticles. We found that the closely-packed monolayer structure of the Fe3O4 nanoparticles changed the magnetic properties on account of the dipolar interactions between particles, whereas the homogeneously-dispersed nanoparticles embedded in the polymer matrix exhibited zero remanent magnetization and coercivity due to isolation of the nanoparticles and lack of dipolar interactions.

Flower-like shaped rutile-rich TiO 2 nanoparticles were synthesized by the reaction of HCl with titanium diisopropoxide bis(acetylacetonate) immobilized in reverse micelles composed of oleic acid, water, and xylene. Brunauer Emmett Teller (BET) analysis showed large surface area of the synthesized TiO 2 nanoparticles of 177.8 m 2 /g. We investigated the effect of the concentration of Ti precursor and role of oleic acid in the formation of TiO 2 nanoparticles. Rutile-rich TiO 2 nanoparticles with large surface area showed better photocatalytic activity in decomposing methyl orange under visible-light irradiation than anatase and rutile mixed phase TiO 2 particles.

Here, we report a simple and fast synthetic route to Ag/AgBr hybrid nanostructures prepared by reducing AgBr nanoparticles synthesized by the reaction of Ag+ with Br− in the presence of polyethyleneimine (PEI). By controlling the experimental conditions including reaction temperature and amount of reducing agent, we could easily control the morphology and composition of a variety of Ag/AgBr hybrid nanostructures including Ag nanoparticles decorated with AgBr nanoparticles and hollow cage-like Ag-rich nanostructures. The Ag/AgBr hybrid nanostructures exhibited enhanced photocatalytic activity and recyclability for decomposing methylene blue (MB) under visible-light illumination because of a small bandgap (2.6 eV) and strong SPR effect. In particular, we found that the Ag/AgBr hybrid nanostructures showed a photocatalytic reaction rate that was 1000 times faster than commercial TiO2 (P-25). In addition, the Ag/AgBr hybrid nanostructures had a higher photocatalytic activity compared to Ag/AgCl hybrid nanostructures towards the decomposition of methyl orange (MO) under visible light illumination.

We report the colloidal synthesis of rare earth oxide nanoplates with square and disk shapes using thermal decomposition of Ln(CH3CO2)3·xH2O in the presence of a mixture of oleylamine and oleic acid (Ln=La, Pr, Nd, Dy, Er, and Y). In this synthesis, oleylamine plays an important role in the formation of ultra-thin nanoplates with thickness of 1.1 nm, which corresponds to a single unit cell dimension of rare earth oxides, and oleic acid serves as a capping agent for the formation of nanoplates having nano-sized side dimension (around 15-40 nm). By varying the rare earth precursors, we obtained square-shaped nanoplates (La2O3, Pr2O3, and Nd2O3) and disk-shaped nanoplates (Dy2O3, Er2O3, and Y2O3), respectively, confirming that our synthesis could be extended to the synthesis of various rare earth oxide nanoplates.

At high concentrations, manganese (Mn) promotes cellular neurodevelopment but causes toxicity. Here, we report that Mn ion at high concentrations can be delivered to pheochromocytoma 12 (PC12) cells using gold nanoparticles (AuNPs) to enhance cellular neurodevelopment without toxicity. Mn(2+) release from AuNPs was designed to be pH-responsive so that low pH condition of the cell endosomes can trigger in situ release of Mn(2+) from AuNPs after cellular uptake of Mn-incorporated AuNPs (MnAuNPs). Due to the differences in reduction potentials of Mn and Au, only Mn ionized and released while Au remained intact when MnAuNPs were uptaken by cells. Compared to PC12 cells treated with a high concentration of free Mn(2+), PC12 cells treated with an equal concentration of MnAuNPs resulted in significantly enhanced cellular neurodevelopment with decreased apoptosis and necrosis. Treatment with a high concentration of free Mn(2+) led to an abrupt consumption of a large amount of ATP for the intracellular transport of Mn(2+) through the ion channel of the cell membrane and to mitochondrial damage caused by the high intracellular concentration of Mn(2+), both of which resulted in cell necrosis and apoptosis. In contrast, MnAuNP-treated cells consumed much smaller amount of ATP for the intracellular transport of MnAuNPs by endocytosis and showed pH-triggered in situ release of Mn(2+) from the MnAuNPs in the endosomes of the cells, both of which prevented the cell death caused by ATP depletion and mitochondrial damage. To our knowledge, this is the first report on the use of AuNPs as a vehicle for pH-responsive, intracellular delivery of metal ion, which may open a new window for drug delivery and clinical therapy.

The synthesis of highly uniform alloy nanocrystals with a concave feature is desirable for applications in catalysis but is an arduous task. This article proposes an initiative protocol for the fabrication of novel Cu-Pd alloy nanocrystals, wherein the volume of decylamine (DA) in the reaction system was found to greatly influence the formation of different morphologies, including the tetrahedron (TH), concave tetrahedron (CTH), rhombohedral-tetrapod (RTP), and tetrapod (TP). The alloy structure of the products arises from the coordination interaction between the DA and metal ions, which affects the reduction potential of Cu and Pd species, and thus yields co-reduction. Other reaction parameters, such as the type of ligand, amount of reductant, and temperature, were also altered to study the growth mechanism, yielding consistent conclusions in the diffusion-controlled regime. As a catalyst, 48-nm Cu-Pd concave tetrahedral nanocrystals were highly active for the hydrogenation of 3-nitrostyrene and exhibited >99.9% chemoselectivity to C=C instead of -NO2.

The hydrothermal decomposition of sodium alginate was analyzed in subcritical water as a function of pH in order to investigate the effects of catalysts on the production of value-added chemicals. A base-catalysed reaction at pH 13 promoted the decomposition of alginate, resulting in the production of lactic acid, fumaric acid and malic acid as major species. At pH 1, monomers (mannuronic acid and guluronic acid), furfural and glycolic acid were predominantly produced by the acid-catalysed hydrothermal decomposition of alginate. Increasing the reaction temperature enhanced both the acid- and base-catalysed reactions, albeit by varying degrees dependent upon the catalyst type. Our results demonstrate that optimizing the reaction temperature and pH is critical for the efficient conversion of seaweed-derived biomass into valuable products.