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The use of carbon-based nanomaterials as effective photocatalysts is an ideal alternative for environmental remediation. Here, (3-aminopropyl)triethoxysilane-functionalized carbon nanoparticles (SiCNPs) were prepared using a simple pyrolysis method with sodium citrate and urea as the precursors. The samples were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and photo-electrochemical measures. The obtained SiCNPs-2.0 showed a better visible light response and more effective photocatalytic activity for degradation of methylene blue (MB) compared with pure CNPs. Under visible light irradiation, 98.8% of the MB was decomposed within 75 min when SiCNPs-2.0 was used as the photocatalyst. The high photocatalytic activities of SiCNPs-2.0 could be attributed to enhanced light absorption in the visible region, and improved photogenerated electron-hole separation efficiency. A possible photocatalytic mechanism for removal of MB over SiCNPs-2.0 was proposed based on active species trapping experiments. Recycling experiments showed that SiCNPs-2.0 had good stability during photocatalysis. This work provides a new easy method to synthesize carbon-based nanomaterials and to catalytically degrade organic pollutants in water under visible light irradiation., (© 2020 John Wiley & Sons, Ltd.)

Gene delivery to stem cells is a critical issue of stem cells-based therapies, still facing ongoing challenges regarding efficiency and safety. Recent advances in the controlled synthesis of biocompatible magnetic iron oxide nanoparticles (IONPs) have provided a powerful nanotool for assisting gene delivery to stem cells. However, this field is still at an early stage, with well-designed and scalable IONPs synthesis highly desired. Furthermore, the potential risks or bioeffects of IONPs on stem cells are not completely figured out. Therefore, in this review, the updated researches focused on the gene delivery to stem cells using various designed IONPs are highlighted. Additionally, the impacts of the physicochemical properties of IONPs, as well as the magnetofection systems on the gene delivery performance and biocompatibility are summarized. Finally, challenges attributed to the potential impacts of IONPs on the biologic behaviors of stem cells and the large-scale productions of uniform IONPs are emphasized. The principles and challenges summarized in this review provide a general guidance for the rational design of IONPs-assisted gene delivery to stem cells., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Single-chain nanoparticles (SCNPs) are generated by intramolecular collapse and crosslinking of single polymer chains, thus conceptually resembling the structures of folded proteins. Their chemical flexibility and ability to form compartmentalised nanostructures sized ∼1 nm make them perfect candidates for numerous applications, such as in catalysis and drug delivery. In this review we discuss principles for the design, synthesis and analysis of SCNPs, with a focus on their compartmentalised structures, highlighting our own previous work. As such compartments offer the potential to generate a specific nanoenvironment e.g. for the covalent and non-covalent encapsulation of catalysts or drugs, they represent a novel, exciting, and expanding research area. Starting from the architectural and chemical design of the starting copolymers by controlling their amphiphilic profile, the embedding of blocks-, or secondary-structure-mimetic arrangements, we discuss design principles to form internal compartments inside the SCNPs. While the generation of compartments inside SCNPs is straightforward, their analysis is still challenging and often demands special techniques. We finally discuss applications of SCNPs, also linked to the compartment formation, predicting a bright future for these special nanoobjects. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyse the potential prospect of electrospinning gelatin nanofiber membranes containing carvacrol nanoparticles (G−Car−NPs−NF) as packaging material in food field. Sustained‐release antioxidant and antibacterial nanofiber membranes were prepared by incorporating the carvacrol nanoparticles (Car−NPs). Carvacrol (Car) was used to form nanoparticles with zein and sodium caseinate, and then electrospinning with gelatin‐based solution to form nanofiber membranes. The biological activities of composite nanofiber membranes were exhibited. The antioxidant capacity was characterized by the scavenging rate of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical. With the increase of the concentration of Car, the antioxidant capacity of G−Car−NPs−NF was gradually improved. In addition, G−Car−NPs−NF exhibited inhibitory effect on Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) and the inhibitory effect was positively correlated with the concentration. Moreover, the nanofiber membranes showed the slow‐release rate in vitro release and kept the appropriate concentration. These results were directly showed that G−Car−NPs−NF could be used as an effective packaging material for Car in food industry. [ABSTRACT FROM AUTHOR]

Highly efficient CO2 reduction to produce fuel driven by solar energy is of great significance to alleviate the greenhouse effect and realize solar energy storage. Herein, a unique nanocomposite of MgO‐cluster‐modified Ni nanoparticles supported on Ni‐doped MgO (MCM–Ni/Ni–MgO) is synthetized by a simple approach. Very high fuel production rate for H2 and CO (78.01 and 88.44 mmol min−1 g−1) as well as a large light‐to‐fuel efficiency (31.7%) are achieved by photothermocatalytic CO2 reduction by CH4 on MCM–Ni/Ni–MgO merely using focused UV–vis–IR illumination. This arises from efficient light‐driven thermocatalysis that is further enhanced by a photoactivation due to the activation energy being considerably reduced upon the illumination. More importantly, it exhibits excellent photothermocatalytic durability due to its extremely low carbon deposition rate of 8.85 × 10−4 gc h−1 g−1catalyst, reduced by 39.2 times as compared with that of a reference sample of Ni nanoparticles supported on Ni‐doped MgO (Ni/Ni–MgO). The experimental evidences and the functional theory calculations reveal that the surface modification of Ni nanoparticles by MgO cluster not only inhibits the carbon deposition side reactions of CO disproportionation and CH4 complete dissociation, but also significantly accelerates the oxidation of carbon species, thus tremendously decreasing carbon deposition rate. [ABSTRACT FROM AUTHOR]

Microencapsulation is considered an efficient technique to protect functional materials from oxidization while enabling controlled release. In this study, anti‐solvent precipitation was used to prepare zein‐based microcapsules loaded with Artemisia argyis essence (AAE@ZMs). The impact of different drying methods, namely vacuum drying, freeze drying, and spray drying on AAE@ZMs was evaluated. Quality of AAE@ZMs was evaluated by the determination of color, moisture content, bulk density, chemical structure, and morphology evaluation. Freeze dried AAE@ZMs (F‐AAE@ZMs) and vacuum dried microcapsules (V‐AAE@ZMs) respectively showed stronger water and oil absorption capacities. The residual content of Artemisia argyis essence (AAE) in V‐AAE@ZMs was higher than those in F‐AAE@ZMs and spray dried microcapsules (S‐AAE@ZMs) after continuously releasing for 120 h. Meanwhile, heated from 30 to 600°C, the residues of V‐AAE@ZMs and F‐AAE@ZMs were lower than those of S‐AAE@ZMs. Therefore, drying methods greatly affected key quality parameters of AAE@ZMs. This study provides guidance on the use of drying methods in microcapsules delivery systems with zein or other materials. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction is a sustainable and inexpensive method to solve the energy crisis and the greenhouse effect. However, the major stumbling blocks such as poor product selectivity, low yield of the multi‐carbon products, and serious recombination of electron‐hole pairs hinder practical application of photocatalysts. Herein, a high‐performance Bi@Bi2MoO6 photocatalyst, Bi nanoparticles grown on the surface of Bi2MoO6 nanosheets with oxygen vacancies, was fabricated via a simple solvothermal approach. Benefiting from the abundant active sites and effective separation of photogenerated carriers of Bi2MoO6 nanosheets, and the localized surface plasmon resonance effect of Bi nanoparticles, the Bi@Bi2MoO6 sample exhibited great photocatalytic CO2 reduction activity. Furthermore, adding NaHCO3 into the system not only significantly increased the C2H5OH generation rate but also enhanced the product selectivity. In the photocatalytic measurement (0.17 mol L−1 CO2‐saturated NaHCO3 solution), the highest formation rates of CO, CH3OH, and C2H5OH were reached at 0.85, 0.59, and 17.93 μmol g−1 h−1 (≈92 % selectivity), respectively. [ABSTRACT FROM AUTHOR]

Catalysts containing bimetallic PtCu-nanoparticles deposited onto carbonaceous and composite SnO2/C supports are prepared by liquid-phase borohydride synthesis. The composition and structure of the synthesized materials, their catalytic activity in the reactions of oxygen electroreduction and methanol electrooxidation, as well as corrosion and morphological stability are investigated. The platinum doping with copper atoms is found to increase the materials' catalytic activity and stability in comparison with Pt/C, regardless of the type of support used. In addition, the multicomponent PtCu/(SnO2/C) catalyst exhibits the highest tolerance to intermediate products of methanol electrooxidation. [ABSTRACT FROM AUTHOR]

The effect of annealing on structural defects and d0 ferromagnetism in SnO2 nanoparticles prepared by solution combustion method is investigated. The as-synthesized SnO2 nanoparticles were annealed at 400-800 °C for 2 h, in ambient conditions. The crystallinity, size, and morphology of the samples were studied using x-ray diffraction and transmission electron microscopy studies. The annealing results in grain growth due to coarsening as well as reduction in oxygen vacancies as confirmed by Raman spectroscopy, photoluminescence spectroscopy, and x-ray photoelectron spectroscopy. All the as synthesized and annealed samples exhibit room temperature ferromagnetism (RTFM) with distinct hysteresis loops and the saturation magnetization as high as ∼0.02 emu/g in as-synthesized samples. However, the saturation magnetization is drastically reduced with increasing annealing temperature. Further the presence of singly charged oxygen vacancies (Vo- signal at g-value 1.99) is confirmed by electron paramagnetic resonance studies, which also diminish with increasing annealing temperature. The observed diminishing RTFM and simultaneous evidences of diminishing O vacancies clearly indicate that RTFM is driven by defects in oxide lattice and confirms primary role of oxygen vacancies in inducing ferromagnetic ordering in metal oxide semiconductors. The study also provides improved fundamental understanding regarding the ambiguity in the origin of intrinsic RTFM in semiconducting metal oxides and projects their technological application in the field of spintronics. [ABSTRACT FROM AUTHOR]

This article proposes a novel humidity sensor based on a low-frequency micromachined electromechanical resonator functionalized with nanoparticles of TiO2 deposited on a preparation layer of Al2O3 nanoparticles. Using a low-frequency resonator allows for obtaining a better immunity to the nonidealities of the conditioning electronics components and minimizes the degradation of the resonator quality due to the deposition of the sensing material. In this article, a relationship is derived between the sensor construction parameters, the obtainable sensor resolution, and the requirements in terms of resolution and accuracy of the measurement system, showing the applicability of such sensors in the context of low-cost, low-power distributed sensing systems. An ad hoc characterization system allowed for characterizing the proposed sensor, proving that this solution is viable and requires a simple preparation route and that the sensor has satisfactory performance in a large humidity range. It was shown that the sensitivity can be increased simply by repeating the TiO2 nanoparticle deposition obtaining at least an increase of the relative sensitivity of 5 ppm/1% RH at each deposition step. [ABSTRACT FROM AUTHOR]

Angiogenesis plays a critical role within the human body, from the early stages of life (i.e., embryonic development) to life-threatening diseases (e.g., cancer, heart attack, stroke, wound healing). Many pharmaceutical companies have expended huge efforts on both stimulation and inhibition of angiogenesis. During the last decade, the nanotechnology revolution has made a great impact in medicine, and regulatory approvals are starting to be achieved for nanomedicines to treat a wide range of diseases. Angiogenesis therapies involve the inhibition of angiogenesis in oncology and ophthalmology, and stimulation of angiogenesis in wound healing and tissue engineering. This review aims to summarize nanotechnology-based strategies that have been explored in the broad area of angiogenesis. Lipid-based, carbon-based and polymeric nanoparticles, and a wide range of inorganic and metallic nanoparticles are covered in detail. Theranostic and imaging approaches can be facilitated by nanoparticles. Many preparations have been reported to have a bimodal effect where they stimulate angiogenesis at low dose and inhibit it at higher doses. [ABSTRACT FROM AUTHOR]

Chemiresistors were constructed using 3-D silica nanospring mats coated with a contiguous film of ZnO nanocrystals. Chemiresistors with an average ZnO nanocrystal radius <3 nm, or >20 nm, were found to exhibit a relative change in conductance of a factor of 50 upon exposure to a gas flow of 20% O2 and 80% N2 with ∼500 ppm of toluene and an operational temperature of 400 °C. Samples with an average ZnO nanocrystal radius of 15 nm were found to be the most responsive with a relative conductance change of a factor of 1000. The addition of metal nanoparticles (average radius equal to 2.4 nm) onto the surface of the ZnO nanocrystals (average radius equal to 15 nm) produced a relative change in conductance of a factor of 1500. For the optimum conditions (T = 400 °C, grain size ∼15 nm) well-defined spikes in conductance to explosive vapors (TNT, TATP) were obtained for 0.1 ms exposure time at ppb levels. [ABSTRACT FROM AUTHOR]

TiO2–CsxWO3 composite particles with mesoporous structure were synthesized in situ via a template-free solvothermal method followed by heat treatment under a hydrogen atmosphere. The effects of the Ti/W molar ratio on the microstructure, transparent thermal insulation, and adsorption/photocatalytic properties of the composite particles were investigated. The introduction of a small amount of n-butyl titanate in the solvothermal reaction solution could induce the formation of mesoporous TiO2–CsxWO3 composite nanoparticles with a particle size of less than 30 nm. With increasing Ti/W molar ratio, the specific surface area of the TiO2–CsxWO3 particles increased, and the crystalline phase was transformed from Cs0.3WO3 to Cs0.32WO3 and gradually to Cs0.2WO3 with a small amount of emerging Ti3O5 crystals. In comparison with the pure CsxWO3 and CsxWO3@TiO2 composite particles with TiO2 coated on CsxWO3, the as-synthesized TiO2–CsxWO3 composite particles in situ showed excellent adsorption/photocatalytic properties for rhodamine B. The mesoporous structure of the composite particles and the good synergistic effect between TiO2 and CsxWO3 greatly improved the adsorption/photocatalytic performance. When the Ti/W ratio was 0.4, TiO2–CsxWO3 particles had the highest adsorption/photocatalytic degradation efficiency for rhodamine B and excellent visible light transmission and near-infrared shielding properties. The results of this work are important for the research and development of nanoparticles with transparent thermal insulation, self-cleaning, and environmental protection functions to alleviate the current building energy consumption and pollutant emissions. [ABSTRACT FROM AUTHOR]

The GO/SnO2 micronanostructure was synthesized by a simple and effective hydrothermal method. The combined characterization methods such as Scanning Electron Microscope (SEM), Transmission electron microscope (TEM), X-ray diffraction (XRD), Element mapping, Energy Dispersive X-Ray Spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), the Raman spectroscopy, the Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), photoluminescence (PL) the Ultraviolet–visible spectroscopy (UV-Vis) and Diffuse reflectance spectrum (DRS) indicated the successful formation of GO/SnO2 micronanostructure. Moreover, the photocatalytic activity tested with RhB aqueous solution revealed that GO/SnO2 had excellent photocatalytic properties compared with SnO2. The photocatalytic efficiency of GO/SnO2 was much higher (about 2.5 times) than that of pure SnO2 under visible light irradiation. Based on these test results, we believe that the present work will provide some thoughts for further fabrication of other novel nanostructures and exploration of their applications. [ABSTRACT FROM AUTHOR]

The selective recognition of nanoparticles (NPs) can be achieved by nanoparticle-imprinted matrices (NAIMs), where NPs are imprinted in a matrix followed by their removal to form voids that can reuptake the original NPs. The recognition depends on supramolecular interactions between the matrix and the shell of the NPs, as well as on the geometrical suitability of the imprinted voids to accommodate the NPs. Here, gold NPs stabilized with citrate (AuNPs-cit) were preadsorbed onto a conductive surface followed by electrografting of p-aryldiazonium salts (ADS) with different functional groups. The thickness of the matrix was carefully controlled by altering the scan number. The AuNPs-cit were removed by electrochemical dissolution. The recognition of the NAIMs was determined by the reuptake of the original AuNPs-cit by the imprinted voids. We found that the recognition efficiency is a function of the thickness of the NAIM layer and is sensitive to the chemical structure of the matrix. Specifically, a subtle change of the functional group of the p-aryldiazonium building block, which was varied from an ether to an ester, significantly affected the recognition of the NPs. [ABSTRACT FROM AUTHOR]

A method of continual ZnO nanoparticle (NP) generation was tested for use in follow-up long-term inhalation exposure experiments with small laboratory animals. NPs were synthesized in an externally heated tube reactor by the evaporation of metallic zinc into a stream of nitrogen carrier gas, followed by the oxidation of zinc vapor in a stream of air and the formation of NPs by a chemical vapor condensation method. The NP production was studied at various evaporation temperatures, reactor flow rates and flow rates of mixing air. Particle generation for more than 100 h in two experimental runs with one batch of the zinc precursor was performed without a considerable decrease in the particle production rate. As a result, particle production with a number concentration much greater than 1.0  107 #/cm3, a mean particle/agglomerate size well below 50 nm and an emission rate greater than 5 μg/min was obtained under most of the investigated experimental conditions. A maximum emission rate of 16.3 μg/min was obtained at an evaporation temperature of 530 °C, a reactor flow rate of 800 cm3/min and a mixing flow rate of 2000 cm3/min and could be further increased by an increase in the evaporation temperature. The particle characteristics were studied, and estimates of the lung surface deposition area were calculated on the basis of the model developed by the International Commission of Radiological Protection. Copyright © 2019 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

MoO3, with advantages of abundance, non‐toxicity and multiple oxidation states, has recently been attracted increasing attention in supercapacitors field as a potential electrode material. Here, a novel composite TiO2/MoO3 had been synthesized and characterized by X‐ray diffraction (XRD), Raman spectra, XPS, scanning electron microscope and transmission electron microscope. The electrochemical results showed the composite has enhanced electrochemical properties with the maximum specific capacitance of 141 F g−1 at the current density of 1 A g−1, which is higher than pure MoO3 at the same test condition. The improved electrochemical properties could be attributed to the synergetic effect and the formation of Ti−O−Mo bonds between TiO2 nanoparticles and MoO3 nanobelts and the increment of specific surface area. This work would not only promote the study about MoO3‐based electrode materials in supercapacitors, but also extended to other transition metal oxides with similar structures. Supercapacitor, as a kind of electrochemical energy‐storage device,has attracted increasing attention in scientific fields. Here, a novel composite TiO2/MoO3 has been synthesized as a potential electrode material. This work could not only promote the study about MoO3‐based electrode materials in supercapacitors, but also extend to other transition metal oxides with similar structures. [ABSTRACT FROM AUTHOR]

Here, we report the design of upconversion nanoparticle-coupled perovskite quantum dots that are full-color tunable under single near-infrared (NIR) excitation. Consequently, we demonstrate the use of these hybrid nanomaterials in printable, NIR-excitable, dual-model anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Abstract: Expanded poly(tetrafluoroethylene) (ePTFE) has been widely used as a vascular graft material due to the fact that it is durable, porous, flexible, and inert. However, ePTFE grafts easily induce thrombosis, calcification and neointimal hyperplasia in small‐diameter (<6 mm) graft bypass surgeries and thus cause surgical failure. Therefore, it is necessary to improve the in vitro and in vivo performances of ePTFE grafts. In this work, we first prepared a polyurethane/polyurethane nanoparticles (PU/PU‐NPs) composite film by a simple cosedimentation method. Compared with the pure PU film, the blood compatibility and the cell compatibility of the PU/PU‐NPs composite film were significantly improved. Then, we constructed a PU/PU‐NPs/ePTFE vascular patch (PPVP) by coating PU and PU‐NPs onto the surface of an ePTFE graft. PU‐NP modification endowed the ePTFE graft with the nanopatterned surface similar to the luminal surface of a blood vessel. PU NPs and the structural likeness of the surface synergistically optimized the overall performance, and thus improved the blood and cell compatibilities, effectively inhibited platelet adhesion, enhanced cell attachment and proliferation, and facilitated the formation of endothelial tissue—endothelialization. The abdominal artery patched with PPVP was not blocked and the endothelialization was achieved 30 days after the implantation. All the results taken together indicate that PPVP may be a promising alternative for a vascular patch. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2131‐2140, 2018. [ABSTRACT FROM AUTHOR]

Abstract: Here, we report the synthesis and near‐infrared photoluminescence properties of small‐diameter (∼2–3 nm) silver and copper nanoparticles. Periodic trends in nanoparticle quantum yields, observed lifetimes, and emission peak features are studied and compared to each other as well as to previously reported small diameter gold nanoparticles. These trends are distinct from optoelectronic features observed from either their cluster (4–100 atoms) or larger NP (diameter >5 nm) counterparts. Taken together, the successful synthesis and characterization of these materials introduces potential alternatives to small, Au‐based nanoparticles in photoluminescence‐driven applications such as bio‐labeling and sensing, as well as provides additional insight into particle properties at this important size range between molecular and bulk materials. [ABSTRACT FROM AUTHOR]

Abstract: The molecular level DNA logic gates assisted by nanomaterials hold great promise for disease diagnosis applications. However, designing convenient and sensitive logic gates for molecular diagnostics still remains challenging. In this work, a DNA logic gate platform for miRNA inputs analysis based on the observation of localized surface plasmon resonance variation of gold nanoparticles (AuNPs) is fabricated. As a demonstration, two biomarkers to differentiate indolent and aggressive forms of prostate cancer, miR‐200c and miR‐605, are selected as examples of logical inputs. In addition, five DNA probes are designed according to strand displacement reaction and hybridization chain reaction which are required for DNA logical operation. Since target miRNA inputs are able to trigger DNA structural transformations, which are further used to precisely regulate salt‐induced AuNPs aggregation, miRNA inputs information can be converted to the information of AuNPs states as outputs. This developed system performs amplified detection of low‐abundant target miRNAs without the requirement of any enzymes. In addition, single base‐pair mismatched miRNAs can be effectively differentiated. High‐order logic gates can also be developed with further modifications. Therefore, the DNA AND logic gate is successfully constructed with flexible operations, which has potential in biochemical study and disease diagnosis. [ABSTRACT FROM AUTHOR]

Platinum nanoparticles stabilized by an imidazolium-based cross-linked polymer (with chloride as the counteranion) efficiently catalyzed the oxidation of 5-hydroxymethylfurfural to form 2,5-furandicarboxylic acid in water under mild conditions with oxygen as the oxidant. This catalyst system is explored herein by varying the counteranion, that is, replacing chloride by BF4-, PF6-, bis(trifluoromethylsulfonyl)imide, hexanoate, or laurate anions, in the cationic polymer. The counteranion influences the structure of the obtained platinum nanoparticles, the surface electronic properties, and their catalytic activity. The highest reaction rates were obtained with the weakly nucleophilic bis(trifluoromethylsulfonyl)imide anion, which also favored platinum in the zero oxidation state, leading to complete conversion of the substrate and a high yield of 2,5-furandicarboxylic acid under mild conditions. [ABSTRACT FROM AUTHOR]

In hybrid materials containing plasmonic nanoparticles such as Au and Ag, charge-transfer processes from and to Au or Ag can affect both activities and selectivity in plasmonic catalysis. Inspired by the widespread utilization of commercial Si wafers in surface-enhanced Raman spectroscopy (SERS) studies, we investigated herein the effect of the native SiO2 layer on Si wafers over the surface plasmon resonance (SPR)-mediated activities of the Au and Ag nanoparticles (NPs). We prepared SERS-active plasmonic comprised of Au and Ag NPs deposited onto a Si wafer. Here, two kinds of Si wafers were employed: Si with a native oxide surface layer (Si/SiO2) and Si without a native oxide surface layer (Si). This led to Si/SiO2/Au, Si/SiO2/Ag, Si/Au, and Si/Ag NPs. The SPR-mediated oxidation of p-aminothiophenol (PATP) to p, p′-dimercaptoazobenzene (DMAB) was employed as a model transformation. By comparing the performances and band structures for the Si/Au and Si/Ag relative to Si/SiO2/Au and Si/SiO2/Ag NPs, it was found that the presence of a SiO2 layer was crucial to enable higher SPR-mediated PATP to DMAB conversions. The SiO2 layer acts to prevent the charge transfer of SPR-excited hot electrons from Au or Ag nanoparticles to the Si substrate. This enabled SPR-excited hot electrons to be transferred to adsorbed O2 molecules, which then participate in the selective oxidation of PATP to DMAB. In the absence of a SiO2 layer, SPR-excited hot electrons are preferentially transferred to Si instead of adsorbed O2 molecules, leading to much lower PATP oxidation. [ABSTRACT FROM AUTHOR]

ZnO and NiO nanopowders are prepared using a simple, cost-effective and eco-friendly green soft chemical method. The XRD studies shows that the prepared powders have high crystallinity with an average crystallite size of 35 and 30 nm, respectively. The EDX study confirms the presence of elements the Zn, Ni and O. Test to find the photocatalytic of ZnO and NiO nanopowders for the degradation of MB dye is performed under visible light. The results reveal that the photocatalytic efficiency of ZnO nanopowders is higher than that of NiO nanopowders. From the antibacterial studies, it is found that the prepared ZnO nanopowder exhibits higher antibacterial efficiency against Escherichia coli and Staphylococcus aureus bacteria than NiO nanopowders. The binding affinity of the bacterial strains with the prepared nanoparticles has been calculated by performing a molecular dynamics simulation and the results are found to be matched well with the experimental studies. [ABSTRACT FROM AUTHOR]

This account provides an overview of current research activities that focus on the synthesis and applications of nanomaterials from noble metal (e.g., Au, Ag, Pd) and iron oxide (Fe3O4) hybrids. An introduction to the synthetic strategies that have been developed for generating M-Fe3O4 nanomaterials with different novel structures is presented. Surface functionalization and bioconjugation of these hybrid nanoparticles and nanocomposites are also reviewed. The utilization of the advantageous properties of both noble metals and iron oxide for a variety of applications, such as theranostics, gene delivery, biosensing, cell sorting, bioseparation, and catalysis, is discussed and highlighted. Finally, future trends and perspectives of these sophisticated nanocomposites are outlined. The fundamental requirements underpinning the effective preparation of M-Fe xO y hybrid nanomaterials shed light on the future development of heterogeneous catalysts, nanotheranostics, nanomedicines, and other chemical technologies. [ABSTRACT FROM AUTHOR]

Pure magnesium aluminate (MgAlO) nanoparticles were successfully synthesized by novel sol-gel method with the aid of Mg(NO).6HO, Al(NO)·9HO, and starch without adding external surfactant. Moreover, starch plays role as capping agent, reducing agent, and natural template in the synthesis MgAlO nanoparticles. The structural, morphological and optical properties of as obtained products were characterized by techniques such X-ray diffraction, energy dispersive X-ray microanalysis, scanning electron microscopy, and ultraviolet-visible spectroscopy. The sample indicated a ferromagnetic behavior, as evidenced by using vibrating sample magnetometer at room temperature. To evaluate the photocatalyst properties of nanocrystalline magnesium aluminate, the photocatalytic degradation of methyl orange under ultraviolet light irradiation was carried out. [ABSTRACT FROM AUTHOR]

A new method is presented for preparing gram amounts of very small core/shell upconversion nanocrystals without additional codoping of the particles. First, ca. 5 nm β-NaYF4:Yb,Er core particles are formed by the reaction of sodium oleate, rare-earth oleate, and ammonium fluoride, thereby making use of the fact that a high ratio of sodium to rare-earth ions promotes the nucleation of a large number of β-phase seeds. Thereafter, a 2 nm thick NaYF4 shell is formed by using 3-4 nm particles of α-NaYF4 as a single-source precursor for the β-phase shell material. In contrast to the core particles, however, these α-phase particles are prepared with a low ratio of sodium to rare-earth ions, which efficiently suppresses an undesired nucleation of β-NaYF4 particles during shell growth. [ABSTRACT FROM AUTHOR]

Pure bismuth aluminate (BiAlO) nanoparticles were successfully synthesized by novel sol-gel method with the aid of Bi(NO), Al(NO)·9HO, and starch without adding external surfactant, capping agent or template. Moreover, starch plays role as capping agent, reducing agent, and natural template in the synthesis BiAlO nanoparticles. The structural, morphological and optical properties of as obtained products were characterized by techniques such X-ray diffraction , energy dispersive X-ray microanalysis, scanning electron microscopy, and ultraviolet-visible spectroscopy. The samples indicated a ferromagnetic behavior, as evidenced by using vibrating sample magnetometer at room temperature. To evaluate the photocatalyst properties of nanocrystalline bismuth aluminate, the photocatalytic degradation of methyl orange under ultraviolet light irradiation was carried out. [ABSTRACT FROM AUTHOR]

A new phase, where peroxo groups are incorporated into titania particles, along with anatase and hydrated η-TiO2 with peroxo groups on the surface of titania nanoparticles were prepared by introduction of H2O2 into reaction mixtures while synthesizing TiO2 from TiOSO4 or by cold impregnation of pre-synthesized TiO2. The samples were studied by a range of methods (classical and synchrotron-radiation X-ray powder diffraction, small-angle X-ray scattering, high-resolution scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray absorption spectroscopy, IR and Raman spectroscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance and absorption spectroscopy, DSC). The [TiOx(O2)2−x(H2O)m] phase was first structurally characterized and compared to η-TiO2. Most samples of H2O2-sensitized TiO2 discolor methyl orange under visible light irradiation faster than commercial Hombikat UV100 treated with H2O2. The activity of the samples strongly relating to their phase composition was associated with the existence of a large amount of titanium peroxo complexes along with formation of mixed-phase samples. [ABSTRACT FROM AUTHOR]

Ag nanoparticle (NP)-decorated MIL-125(Ti) microspheres (Ag@MIL-125(Ti)) were firstly fabricated via a facile hydrothermal and following photo-reduction method. The photocatalysts were characterized using X-ray diffraction, scanning and transmission electron microscopies, and UV-visible spectroscopy. The characterization results indicated that Ag NPs were dispersed on the surface of MIL-125(Ti) microspheres, and the Ag NPs had a uniform diameter of about 40 nm. The composites exhibited excellent visible-light absorption, due to the modification with the Ag NPs. The photocatalytic activity for the visible-light-promoted degradation of Rhodamine B was improved through the optimization of the amount of Ag loaded as a co-catalyst, this amount being determined as 3 wt%. Additionally, studies performed using radical scavengers indicated that O2− and e− served as the main reactive species. The catalyst can be reused at least five times without significant loss of its . Furthermore, a photocatalytic mechanism for degradation of organics over Ag@MIL-125(Ti) is also proposed. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

An ultrasensitive surface-enhanced Raman spectroscopy (SERS) sensor based on rolling-circle amplification (RCA)-increased 'hot-spot' was developed for the detection of thrombin. The sensor contains a SERS gold nanoparticle@Raman label@SiO2 core-shell nanoparticle probe in which the Raman reporter molecules are sandwiched between a gold nanoparticle core and a thin silica shell by a layer-by-layer method. Thrombin aptamer sequences were immobilized onto the magnetic beads (MBs) through hybridization with their complementary strand. In the presence of thrombin, the aptamer sequence was released; this allowed the remaining single-stranded DNA (ssDNA) to act as primer and initiate in situ RCA reaction to produce long ssDNAs. Then, a large number of SERS probes were attached on the long ssDNA templates, causing thousands of SERS probes to be involved in each biomolecular recognition event. This SERS method achieved the detection of thrombin in the range from 1.0×10−12 to 1.0×10−8 M and a detection limit of 4.2×10−13 M, and showed good performance in real serum samples. [ABSTRACT FROM AUTHOR]

Recently, we have reported several catalytic applications of new PdFe3O4 heterodimeric nanocrystals as magnetically separable catalysts. Successful applications of the nanocrystals towards various useful organic reactions such as Suzuki, Heck, and Sonogashira coupling reactions, direct CH arylation, and Wacker oxidation have been recorded. However, detailed mechanistic courses of the reactions have not been delineated, and it was not clear whether these processes proceeded through a homogeneous or heterogeneous mechanism. Here, we report detailed mechanistic investigations of the reactions employing the PdFe3O4 nanoparticle catalysts. Suzuki coupling and Wacker oxidation reactions were chosen as two representative heterogeneous reactions employing the PdFe3O4 catalysts, and general kinetic studies, hot filtration tests, and three-phase tests were carried out for the two reactions. The studies showed that the reactions most probably proceed via a solution-phase mechanism. [ABSTRACT FROM AUTHOR]

SnZn(OH)6 (ZHS) hollow cubes were synthesized by a facile self-templated method at room temperature, and Ag/AgCl/ZHS particles were prepared by a photodepositing method. The crystalline structure and morphology of the prepared particles were characterized by x-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, and N2 adsorption. The results indicated that the particles had almost uniform monoclinic geometry and size. The photocatalytic oxidation of Rhodamine B was used to evaluate the photocatalytic activity of the synthesized photocatalysts. It is found that the hollow Ag/AgCl/ZHS showed the highest catalytic performance under visible or UV light, which can be attributed to the synergetic effect of Ag, AgCl, and ZHS. [ABSTRACT FROM PUBLISHER]

Heavy metal fluorides like BiF3 as a host for lanthanide ions are of interest as bismuth is the only heavy metal that is nontoxic. In this work, we report the synthesis of highly water-dispersible ultrasmall BiF3 nanoparticles about 6 nm in size within a poly(vinyl pyrrolidone) matrix by a hydrothermal method. Microscopy analysis reveals that the nanoparticles are well separated and confined within the polymer network. These nanoparticles were found to be excellent hosts for lanthanide (Ln3+) ions. Through suitable Ln3+ doping, BiF3 exhibits strong emissions in the visible region upon both UV and near infrared (NIR) excitations. The non-toxicity of both bismuth and PVP can be advantageous for the potential use of BiF3 nanoparticles in drug delivery and bioimaging. [ABSTRACT FROM AUTHOR]

One-dimensional mesoporous TiO2-Bi2WO6 hollow superstructures are prepared using a hydrothermal method and their photocatalysis and recycle properties are investigated. Experimental results indicate that anatase TiO2 nanoparticles are coupled with hierarchical Bi2WO6 hollow tubes on their surfaces. The TiO2-Bi2WO6structure has a mesoporous wall and the pores in the wall are on average 21 nm. The hierarchical TiO2-Bi2WO6heterostructures exhibit the highest photocatalytic activity in comparison with P25, pure Bi2WO6 hollow tube and mechanical mixture of Bi2WO6 tube and TiO2 nanoparticle in the degradation of rhodamine B (RhB) under simulated sunlight irradiation. The as-prepared TiO2-Bi2WO6heterostructures can be easily recycled through sedimentation and they retains their high photocatalytic activity during the cycling use in the simulated sunlight-driving photodegradation process of RhB. The prepared mesoporous TiO2-Bi2WO6with hollow superstructure is therefore a promising candidate material for water decontamination use. [ABSTRACT FROM AUTHOR]

In this article, hexagonal phase NaYF4:Yb,Er (β-NaYF4:Yb,Er) nanoparticles with a controlled size and morphology were synthesized via a simple and environmentally friendly method under relatively mild conditions. The different F−/Y3+ molar ratios were used in the synthesis of hexagonal Yb3+,Er3+ codoped NaYF4 nanocrystals as a means of controlling the size and morphology of the nanocrystals. Subsequently, the morphology and structure of the products were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effect of the F−/Y3+ molar ratio on the size and morphology of the products was examined. When the F−/Y3+ molar ratio was gradually increased, the products transformed from spherical hexagonal nanocrystals to regular hexagonal nanocrystals and the size of the products changed from 8 to 400 nm. That is to say, excessive F− ions were capable of accelerating for the formation of larger β-NaYF4:Yb,Er nanoparticles in our synthesis procedure. Meanwhile the upconversion photoluminescence of the nanocrystals was investigated in detail by fluorescent spectroscopy to reveal the relationship between the optical properties and the morphology and size of the products. As a consequence, the upconversion photoluminescence of the nanocrystals demonstrated a morphology and size dependence. Thus the fabrication of β-NaYF4:Yb,Er nanoparticles with different sizes and morphologies would satisfy the diverse requirements in various fields. [ABSTRACT FROM AUTHOR]

We employed metal-induced lateral crystallization (MILC), using Ni nanoparticles synthesized within cage-shaped protein molecules, to crystallize an amorphous Si film into a polycrystalline film. This process allowed us to choose the crystallization sites of the polycrystalline silicon (poly-Si) film and enlarged the average grain size. We fabricated cantilever resonators from the poly-Si film to characterize them and extract quality factors. The reference resonator, fabricated without MILC, had a quality factor of 12 100, while the resonator crystallized along the axial direction had a quality factor of 26 200. Two-fold increase was achieved by tuning the crystal structure of the poly-Si film. [ABSTRACT FROM AUTHOR]

A magnetic personality: Magnetofection and gene delivery have been investigated in HepG2 cells using ternary organic–inorganic hybrid nanocomposites that contain deferoxamine ‐ coated iron oxide nanoparticles (NPs), circular plasmid DNA, and branched polyethylenimine (PEI). It was found that the cellular uptake efficacies depend on the ratio of components in PEI/DNA/NP, as assessed by Prussian staining, magnetic resonance imaging, and luciferase expression in the presence and absence of a magnet during transfection. [ABSTRACT FROM AUTHOR]

Low temperature (25 °C–80 °C) synthesis of zinc oxide (ZnO) nanoparticles (<20 nm) at short synthesis periods (∼30 min) was achieved by precipitation. The precipitation system was formed using zinc acetate dihydrate as zinc source, ethylene glycol (EG) as solvent and polyvinyl pyrrolidone (PVP) as chelating agent. The size of spherical ZnO nanoparticles was manipulated by the choice of precipitation temperature (13.0 ± 1.9 nm at 25 °C and 9.0 ± 1.3 nm at 80 °C), which essentially changes the nature of adsorption events between ZnO crystals and organic molecules. The particle size can also be regulated by the amount of chelating agent as a result of further enhancement in adsorption between ZnO crystals and organic additives. The spherical ZnO nanoparticles were agglomerated into triangular form when different solvent was used – by substituting water for EG, which has different adsorption ability. Accordingly, formation and growth mechanisms controlling the size and morphology of ZnO nanoparticles have been proposed. [ABSTRACT FROM PUBLISHER]

Intriguing ZnO three-dimensional (3D) dendritic nanorods on silicon substrates have been successfully synthesised by thermal evaporation of pure zinc powder at a relative low temperature of 478°C without any metal catalyst. ZnO dendritic nanostructure exhibits unique shape and it is composed of stems and nanorod branches. It is found that the nanorods are single crystalline wurtzite structures, and each nanorod grows along the [0001] direction. At different growth temperatures, the shapes of ZnO nanostructures can be altered. System analysis reveals that the formation and morphology of ZnO dendritic nanostructures are sensitive to the growth temperature. Finally, room temperature photoluminescence spectrum is also investigated, revealing that the ZnO dendritic nanostructure could find application in UV optoelectronic devices; the nanostructure implies some potential applications for nanoscale functional devices. [ABSTRACT FROM AUTHOR]

Nanoparticles of bismuth iron oxide were synthesized via a soft chemical route. X-ray diffraction measurements indicated that the nanoparticles are of a pure perovskite phase. The gas-sensing properties of the nanoparticles were examined. It is found that bismuth iron oxide nanoparticles are sensitive to several organic gases (e.g., acetone and alcohol) with an ultralow detection limit, rapid response, fast recovery, and good selectivity. [ABSTRACT FROM AUTHOR]

UCNPs (NaYF4) were efficiently converted to a self-assembled network of a low molecular-weight gelator, thus reinforcing the gel structure and leading to the formation of hybrid multi-colour system through excitation by NIR light. [ABSTRACT FROM AUTHOR]

Nanoparticle (NP) assemblies have been studied over the past several decades, and the field is advancing more quickly and reaching into more diverse fields. Reports issued from academic and industrial laboratories have driven these advances. Countless breakthroughs have been reported in widely different fields, including thermoelectronics, photoelectronics, catalysts, energy sources, and medical carriers. A "family tree" is clearly needed to accurately trace the developments in the study of NP assemblies. This review uses the unconventional approach of comparing the atomic and NP worlds to describe the development of NP research during the past several decades. The corresponding classifications, such as atoms and NPs, molecules and molecular‐type NP assemblies, crystals and crystalline‐type NP assemblies, biological organisms and analogous artificial assemblies, and biologically functional NP complex assemblies, are discussed in detail. It concludes with remarks concerning the trend from nonliving to living applications of NP assemblies. The architectural evolution of the nanoparticle world in analogy to the development of biological life from the nonliving atom world is reviewed. The structural classifications of the nonliving nanoparticle world are summarized as well as their special properties in various applications. Inspired architectural nanoparticle assemblies with living function and future evolution direction are also forecasted. [ABSTRACT FROM AUTHOR]

Conductive, carbon-free, electrocatalytically active, nanostructured electrodes with ultra-low platinum loading were fabricated using self-assembly of octadecanethiol-coated Au@Pt nanoparticles followed by RF plasma treatment. Bilayer arrays of Au@Pt nanoparticles with platinum loadings of 0.50, 1.04, 1.44, and 1.75 μg cm−2 (corresponding to 0.5, 1, 1.5 and 2 atomic layer coverage of platinum on nominally 5 nm gold core) were subjected to RF argon plasma treatment for various durations and their electrical conductivity, morphological evolution, and electrocatalytic activity characterized. Samples with monolayer and above platinum coverages exhibit maximum electrochemically active surface areas values of ∼100 m2/gpt and specific activities that are ∼4× to 6× of a reference platinum nanoparticle bilayer array. The underlying gold core influences the structural evolution of the samples upon RF plasma treatment and leads to the formation of highly active Pt(110) facets on the surface at an optimal plasma treatment duration, which also corresponds to the onset of a sharp decline in lateral sheet resistance. The sample having a two atom thick platinum coating has the highest total mass activity of 48 ± 3 m2/g(pt+au), corresponding to 44% Pt atom utilization, while also exhibiting enhanced CO tolerance as well as high methanol oxidation reaction and oxygen reduction reaction activity. [ABSTRACT FROM AUTHOR]