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Graphical abstract Abstract Hypothesis Capillary interactions play an important role in directing colloidal assembly on fluid interfaces. Interface curvature is expected to influence not only individual particle migration on interfaces but also capillary forces between nearby particles. In drying droplets, we hypothesize that the assembly and deposition of particles bound to droplet surface are controlled by the interplay between capillary effects and evaporation-driven flow. Experiments Using lattice Boltzmann–Brownian dynamics (LB–BD) simulations, we modeled large-scale assembly of nanoparticles on fluid interfaces that have complex geometries and investigate the subsequent deposition upon complete evaporation. A systematic study was performed for geometrically-controlled sessile droplets whose surfaces exhibit varying curvature fields. Findings The simulations show that the particle dynamics on nonuniformly curved interfaces are anisotropic and governed by particle-pair capillary interactions and curvature-induced capillary migration. A theoretical model was developed to predict the capillarity-induced assembly. Using the curved surface as a template, drying droplets with surface-bound particles deposit distinct patterns as a result of the competition between the capillary effects and evaporation-induced convection. These findings could provide new opportunities in the directed assembly and deposition of colloidal particles with potential applications in fabricating functional materials from nanoscale building blocks. [ABSTRACT FROM AUTHOR]

The solvent-induced precipitation in a mixture of good and poor solvents was often used to synthesize organometal halide perovskite nanocrystals (OMHP NCs). Here we investigate the formation of OMHP NCs by using HBr based precursors in various solvents. Various emission colors and morphologies of perovskite NCs were obtained depending on the solvents used. The nanoplatelets with blue emission were produced for the low polar solvents, such as toluene, PhCl and EtOAc. The increase in polarity of poor solvents results in the red shift of emission of obtained NCs. The much more polar solvents like acetone and CH 3 CN lead to formation of CH 3 NH 3 PbBr 3 NCs (MaPbBr 3 ) with cubic phase. The dispersion behaviors of MaPbBr 3 NCs in different solvents was also investigated. MaPbBr 3 NCs can exist stably in most unpolar solvents. However, they will be dissolved in polar solvents, like acetone and acetonitrile, to give rise to a clear solution with red emission of Pb 2+ . By injecting this clear solution to unpolar solvents, OMHP NCs can be reproduced. [ABSTRACT FROM AUTHOR]

We reported a simple and ultrafast route to synthesize the bifunctional Er 3+ /Yb 3+ -codoped NaBiF 4 upconverting nanoparticles. It was found that the phase composition and microstructure of the prepared samples were strongly dependent on the NH 4 F content. When the NH 4 F content was 14 mmol, after 1 min reaction at room temperature, the resultant compounds exhibited pure single phase and were composed of uniform spherical nanoparticles. Under 980 nm light irradiation, the synthesized nanoparticles emitted visible emissions originating from the intra-4f transitions of Er 3+ ions and the involved upconversion luminescence mechanism was associated with the typical two-photon process. With the aid of the fluorescence intensity ratio technique, the optical thermometric behaviors of the studied nanoparticle based on the ( 2 H 11/2 , 4 S 3/2 ) thermally-coupled levels in the temperature range of 303–483 K were systematically analyzed and the maximum sensor sensitivity was determined to be about 0.0057 K −1 at 483 K. Furthermore, the internal heating properties of the resultant nanoparticles induced by the laser power source were also studied. With elevating the pump power from 159 to 658 mW, the temperature of the upconverting nanoparticles was improved from 304 to 464 K. These results suggest that the Er 3+ /Yb 3+ -codoped NaBiF 4 upconverting nanoparticles are promising bifunctional luminescent materials for nanothermometer and optical heater applications. [ABSTRACT FROM AUTHOR]

Hyperbranched polymers have attracted wide research attention owing to their unique topological structure, physicochemical properties and great potential for applications such as additives, drug delivery, catalysts and nanotechnology. Among these, the polyamidoamine (PAMAM) dendrimers are some of the most important dendrimers. However, the synthesis and biomedical applications of fluorescent PAMAM dendrimers have received only limited attention. In this work, we present a rather effective and convenient approach for synthesis of fluorescent PAMAM dendrimers with aggregation-induced emission (AIE) properties through a one-pot catalyst-free Mannich reaction under rather mild experimental conditions (e.g., low reaction temperature, air atmosphere in the presence of water). The obtained AIE-active amphiphiles (PhE-PAD) could self-assemble into fluorescent organic nanoparticles (FONs). The obtained AIE-active FONs (PhE-PAD FONs) were fully characterized, and their successful construction was confirmed by 1 H NMR spectroscopy, FT-IR spectroscopy and transmission electron microscopy. Fluorescence and UV–Visible absorption spectroscopy results demonstrated that the final PhE-PAD FONs showed strong yellow fluorescence, desirable photostability and good water dispersity. The cell viability evaluation and confocal laser scanning microscope imaging results suggested that PhE-PAD FONs possessed low cytotoxicity and excellent biocompatibility. Taken together, these results demonstrate that we have developed a facile and efficient strategy for the fabrication of AIE-active FONs, which possess many desirable features for biomedical applications. [ABSTRACT FROM AUTHOR]

Monodisperse and uniform high-quality MCM( M obil C omposition of M atter)-48-type CMSNs ( C ubic M esoporous S ilica N anoparticle s ) are readily prepared by simply optimizing the molar ratio of ethanol and surfactant in the system TEOS-CTAB-NaOH-H 2 O-EtOH (TEOS = t etra e thyl o rtho s ilicate, CTAB = c etyl t rimethyl a mmonium b romide, EtOH = ethanol). In the absence of ethanol only hexagonal mesoporous silica with ellipsoidal and spherical morphology are obtained. The presence of ethanol drives a mesophase transformation from hexagonal to mixed hexagonal/cubic, further to purely cubic, and finally to a mixed cubic/lamellar. This is accompanied by a morphology evolution involving a mixture of ellipses/spheres, regular rods, uniform spheres, and finally a mixture of spheres/flakes. Preserving the three-dimensional (3D) cubic MCM-48 structure, use of a small amount of ethanol is beneficial to the improvement of the monodispersity of the CMSNs. Moreover, the quality of the CMSNs can also be controlled by changing the surfactant concentration or adjusting the stirring rate. All MSNs were characterized using powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and N 2 physisorption, indicating highly long-range ordered pore arrays, high specific surface areas (max. 1173 m 2 g −1 ) as well as high pore volumes (max. 1.14 cm 3 g −1 ). The monodispersity of the CMSNs was verified by statistical particle size distribution from SEM ( s canning e lectron m icroscopy)/TEM ( t ransmission el ectron m icroscopy) images and DLS ( d ynamic l ight s cattering). The mesophase transformation can be rationalized on the basis of an ethanol-driven change of the surfactant packing structure and charge matching at the surfactant/silicate interface. The corresponding morphology evolution can be elucidated by an ethanol-controlled hydrolysis rate of TEOS and degree of condensation of oligomeric silicate species via a nucleation and growth process. [ABSTRACT FROM AUTHOR]

[Display omitted] A flexible solid rechargeable Zn-air battery for advanced energy conversion and storage has extensive applications in portable electric sources, wildlife rescue and flexible wearable systems. Herein, the CoSe 2 nanoparticles anchored on cobalt-embedded N -doping carbon nanoplates (CoSe 2 /CoNC) is developed as a highly active bifunctional catalyst via pyrolysis and selenization of bimetallic zeolitic imidazolate frameworks containing Zn and Co. The introduction of inactive Zn generates strong electrochemically active surface areas due to the synergistic effect between CoSe2 nanoparticles and CoNC matrix. Further, CoSe2/CoNC exhibits prominent Zn–air battery performance and even outperforms the commercially available noble-metal catalysts. Notably, a high-rate flexible Zn-air battery enabled by an alkaline composite polyacrylic acid-carboxymethyl cellulose electrolyte delivers the open-circuit potential of 1.51 V. The battery offers high wearability and performs very well under various conditions, such as soaking, drilling and sewing. [ABSTRACT FROM AUTHOR]

Abstract: Although nanoparticle impacts on a solid surface always occur in natural or engineering processes and cause extensive investigations, less works have been reported on the nanoparticle–wall collisions in a liquid. In present paper, by considering the inertial effect and the Brownian motion of nanoparticles, a theoretical model was established for calculating the collision frequency between the nanoparticles and the solid surface in a laminar cylindrical liquid jet impacting normally on the solid surface. The analysis showed that the collision frequency grows as the square root of the impacting speed for low impacting speed regime in which the Brownian motion is predominant, whereas increases as the second power of the impacting speed for high impacting speed regime in which the inertial effect is predominant. Meanwhile, an observation system for nanoparticle–wall collisions in a laminar cylindrical liquid jet has been developed. The adsorption of the nanoparticles on the solid surface after collision has also been observed. Because of their lower attractive energy with the solid surface, these adsorbed nanoparticles are easier to be removed by the Fundamental Research Funds for the Central Universities (Grant No. YX2011-9), the Beijing Forestry University Young Scientist Fund (Grant No. 2010BLX08), the hydrodynamic force of the impacting liquid than that deposited on a dry surface. [Copyright &y& Elsevier]

Abstract: Cryogenic scanning electron microscopy (cryo-SEM) was used to investigate microstructure development of composite coatings prepared from dispersions of antimony-doped tin oxide (ATO) nanoparticles (∼30 nm) or indium tin oxide (ITO) nanoparticles (∼40 nm) and latex particles (polydisperse, : ∼300 nm). Cryo-SEM images of ATO/latex dispersions as-frozen show small clusters of ATO and individual latex particles homogeneously distribute in a frozen water matrix. In contrast, cryo-SEM images of ITO/latex dispersions as-frozen show ITO particles adsorb onto latex particle surfaces. Electrostatic repulsion between negatively charged ATO and negatively charged latex particles stabilizes the ATO/latex dispersion, whereas in ITO/latex dispersion, positively charged ITO particles are attracted onto surfaces of negatively charged latex particles. These results are consistent with calculations of interaction potentials from past research. Cryo-SEM images of frozen and fractured coatings reveal that both ceramic nanoparticles and latex become more concentrated as drying proceeds; larger latex particles consolidate with ceramic nanoparticles in the interstitial spaces. With more drying, compaction flattens the latex–latex particle contacts and shrinks the voids between them. Thus, ceramic nanoparticles are forced to pack closely in the interstitial spaces, forming an interconnected network. Finally, latex particles partially coalesce at their flattened contacts, thereby yielding a coherent coating. The research reveals how nanoparticles segregate and interconnect among latex particles during drying. [Copyright &y& Elsevier]

Abstract: Silica nanoparticle/mesoporous silica composite films were prepared by direct mixing with mechanical stirring and thermal imidization. The structural morphology was elucidated by scanning electron microscopy and the surface of the film was imaged by atomic force microscopy. The functional groups and desorption process of the films were elucidated by Fourier transform infrared spectroscopy and thermal desorption spectroscopy. The mechanical properties were investigated using a nanoindenter system. The gel matrix and the filler are very compatible because they have similar molecular content. The composite films had a higher mechanical strength than pure porous silica film. Their strength is related to the silica nanoparticle content. The interfacial compatibility, dispersion effect, and interfacial strength also affect the mechanical strength of composite films. [Copyright &y& Elsevier]

Abstract: Surface enhanced Raman scattering (SERS) spectra of C60 (C70) were obtained in nonaqueous colloidal systems with newly developed methods. The enhancement factor was estimated to be over 105. This paper aims at the investigation of a fine influence mechanism for SERS in the nonliquid phase, which may help bring forth the perfect SERS mechanism. The detailed investigation is based on abundant comparative experiments where we found that the SERS effect is sensitive not only to the character of colloidal particles, dielectric constants, and polarizability, but also to the substrates, the solvent intermediate, and even the coating techniques. These detailed comparisons enrich the proofs of the SERS mechanism and provide a new way to optimize SERS systems. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles were prepared under mild conditions by exploiting poly(ethylene glycol) (PEG) in the absence of other chemicals. The chain length of PEG was discovered to play the key role in the formation of silver nanoparticles. Ethylene glycol, which was used as a reducing agent for the preparation of metal particles at high temperatures (>170 °C), was inactive for the reducing of Ag+ at 80 °C. Surprisingly, Ag+ can be smoothly reduced to silver nanoparticles at the same condition in PEG 2000. Further studies demonstrated that the reducing rate of Ag+ to nano-Ag was remarkably enhanced with the increase of polymer chain length of PEG. The particle size depended upon the reaction temperature and concentration of the precursor and an increase in temperature effected a shift of particle size range from ca. 10 to 80 nm. In addition, a noticeable change of sphere to polyprism nanosilver was observed when the reaction temperature was elevated to 120 °C. [Copyright &y& Elsevier]

Abstract: SERS of C60/C70 adsorbed on gold nanoparticles coated on filter paper or filter film was studied. As a new SERS substrate, dried gold-coated filter paper or filter film has a high SERS activity, whose enhancement factor can be up to about 105, because it avoided the influence of solvents in C60/C70 solution and water in gold hydrosols. The influence of the gold thickness coated on filter paper or filter film to SERS of C60/C70 adsorbed on gold nanoparticles was mainly discussed. It is indicated that the SERS effect of C60/C70 was very sensitive to the distribution and aggregated characteristics of gold nanoparticles, and the SERS intensity of each mode increased at its own proportion, but it integrally tended to saturation when the thickness of colloidal gold coatings increased. [Copyright &y& Elsevier]

[Display omitted] Coffee rings formed by evaporation of analyte-containing droplets are widely observed in micropatterning, bio-arrays, and trace detection. The coffee-ring effect caused by contact line pinning significantly affects the detection uniformity and sensitivity. Here, we propose a simple and operable method to effectively suppress coffee rings through controllable nanoparticles aggregation by superhydrophobicity-enabled dynamic evaporation. The gold nanoparticles (AuNPs) deposition footprint formed after dynamic evaporation on an integrated superhydrophobic surface was reduced by ∼3 orders of magnitude compared to that of non-interventional evaporation. Detailed experiments, numerical simulations, and theoretical studies have revealed that substrate wettability, temperature and droplet motion behaviors play significant roles in suppressing coffee-ring effect. More critically, based on the force mechanism of AuNPs at the interface/contact line, universal mathematical models and regime maps were established to classify the different deposition modes for AuNPs under different evaporation conditions by introducing dimensionless parameter G, revealing the enrichment mechanism of AuNPs in droplets under superhydrophobicity-enabled dynamic evaporation. The accuracy of the theoretical model and enrichment mechanism was demonstrated through the single-molecule detection of rhodamine 6G with excellent sensitivity (10–17 M, enhancement factor ∼1013) and perfect uniformity (relative standard deviation ∼5.57 %), which provides a valuable guide for research and applications of nanoparticle aggregation. [ABSTRACT FROM AUTHOR]

A series of PtCoCu ternary nanoalloys decorated carbon nanotube composites (TS-PtCoCu/CNTs) were synthesized by a facile ultrafast thermal shock strategy via Joule heating. The synthesized TS-PtCoCu/CNTs achieved superb catalytic activity toward EOR. An underlying EOR catalytic mechanism of PtCoCu/CNTs was put forward as follows: (i) The small and good dispersed ternary Pt-Co-Cu nanoparticles, the CNT supports and the lattice defects/atomic steps synergistically contribute to the superior catalytic activity and stability. (ii) The incorporation of Co-Cu results in the downshifted d-band center of Pt and enhanced anti-poisoning ability toward CO. (iii) The Co-Cu atoms efficiently assist the adsorption of OH, leading to the preferable C1 reaction path. [Display omitted] • TS-PtCoCu/CNTs was obtained via an ultrafast thermal shock (TS) synthesis. • TS synthesis enables high load and uniform dispersion of nanosized PtCoCu alloys. • TS-PtCoCu/CNTs displays high activity and long stability toward EOR. • Incorporation of Co/Cu atoms into Pt lattice results in downshifted d-band center. • DFT calculations reveals weakened CO adsorption, increased OH affinity and optimized C1 path. Due to the challenges involved in achieving high metal load, uniform metal dispersion and nanosized metal particles simultaneously, it is difficult to develop a simple protocol for the rapid and efficient synthesis of Pt-based composites for electrocatalytic ethanol oxidation reaction (EOR). In this study, a facile ultrafast thermal shock strategy via Joule heating was applied to fabricate a series of PtCoCu ternary nanoalloys decorated carbon nanotube composites (TS-PtCoCu/CNTs), without the need for a reducing agent or surfactant. The TS-PtCoCu/CNTs with optimal Pt content (∼15 %) exhibited excellent EOR activity, with mass and specific activity of 3.58 A mg Pt −1 and 5.79 mA cm−2, respectively, which are 3.8 and 13.5 times higher than those of Pt/C. Compared with the control prepared through the traditional furnace annealing, the catalyst also showed excellent activity and stability. DFT calculations revealed that the TS-PtCoCu/CNTs possesses a downshifted d-band center, weakened CO adsorption and higher OH affinity compared with monometallic Pt, all of which lead to the preferred C1 pathway for EOR. This study demonstrates an ultrafast construction of a highly efficient Pt-Co-Cu ternary catalyst for EOR. Additionally, it provides insights into the reaction mechanism based on structural characterization, electrochemical characterization, and theoretical calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen doped carbon nanotubes with encapsulated Ni nanoparticles have been coated with Ni-MOF. • Ni-MOF@Ni-NCNT exhibited a superior UOR activity due to its lower binding strength with CO 2 and more active sites. • HER-UOR system requires only 1.33 V to reach 10 mA cm−2 for Ni-MOF@Ni-NCNT, 270 mV lower than Pt/C-IrO 2. In this work, we report a robust bifunctional electrocatalyst composed of 2D Ni- organic frameworks (Ni-MOF) and nitrogen doped carbon nanotubes encapsulated Ni nanoparticles (Ni-MOF@Ni-NCNT) for C N and H O bonds dissociation. Due to the presence of Ni-NCNT, adsorption of OH– species is enhanced and CO 2 binding strength is simultaneously weakened leading to a boosted urea oxidation reaction performance reflected by decrement in potential at 100 mA cm−2 by 69 mV. The loosened binding strength with CO 2 specie is highlighted by in-situ electrochemical impedance spectroscopy (EIS) test and DFT calculation. Moreover, the alkaline hydrogen evolution reaction (HER) performance of Ni-MOF@Ni-NCNT is better than Ni-MOF and Ni-NCNT evidenced by the overpotential at 50 mA cm−2 decreased by 224 mV and 900 mV ascribed to the synergistic effect, in which Ni-MOF, Ni nanoparticles and Ni-Nx-C facilitates water adsorption, dissociation and adsorption/combination of hydrogen ions, respectively. The assembled HER- urea oxidation reaction (UOR) system requires only 1.33 V to reach 10 mA cm−2, 70 mV lower than water splitting driven by Pt/C-IrO 2. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical nitrate (NO 3 −) reduction is a promising approach to relieve nitrate pollution and produce value-added ammonia (NH 3), but efficient and durable catalysts are required due to the large bond dissociation energy of nitrate and low selectivity. Herein, we propose chromium carbide (Cr 3 C 2) nanoparticles loaded carbon nanofibers (Cr 3 C 2 @CNFs) as electrocatalysts to convert nitrate to ammonia. In phosphate buffer saline containing 0.1 mol L−1 NaNO 3 , such catalyst achieves a large NH 3 yield of 25.64 mg h−1 mg−1 cat. and a high faradaic efficiency of 90.08% at −1.1 V vs the reversible hydrogen electrode, which also shows excellent electrochemical durability and structural stability. Theoretical calculations reveal the adsorption energy for nitrate at Cr 3 C 2 surfaces reaches −1.92 eV and the potential determining step (*NO→*N) for Cr 3 C 2 hits a low energy increase of 0.38 eV. [ABSTRACT FROM AUTHOR]

Graphical abstract Fe/ZnFe 2 O 4 or Fe@ZnFe 2 O 4 flakes or microspheres were produced by an in-situ growth method and their effective absorption properties covered 6.2 GHz. Abstract In this research, a facile in-situ growth method was applied to load ZnFe 2 O 4 nanoparticles on carbonyl iron (Fe) flakes. These loaded ZnFe 2 O 4 exhibited cone shape with an average size of ∼200 nm. The results revealed that the frequency region with reflection loss <−10 dB (f E) was up to 6.2 GHz (d = 1.5 mm), suggesting excellent wideband electromagnetic absorption (EM) properties. The electromagnetic absorption mechanism was discussed in depth which attributed to the synergetic effect of Fe and ZnFe 2 O 4. The loaded ZnFe 2 O 4 played a key role on suppressing inverse electromagnetic radiation, eddy effect, simultaneous maintaining moderate magnetic loss ability. Besides, the formed interface of ZnFe 2 O 4 /Fe could induce interface polarization relaxation effect at external electromagnetic field, which greatly boosted the effective dielectric loss ability (ε'' E). Meanwhile, the interface polarization intensity was controllable by tuning the weight ratio of Fe. [ABSTRACT FROM AUTHOR]

Cu nanoparticles decorated juncus-derived carbon performs efficiently for electrocatalytic NH 3 production via NO 2 – reduction reaction, capable of achieving a high Faradaic efficiency of 93.2% and a large NH 3 yield of 523.5 μmol h−1 mg cat. −1. [Display omitted] Electrocatalytic nitrite reduction to value-added NH 3 can simultaneously achieve sustainable ammonia production and N -contaminant removal in natural environments, which has attracted widespread attention but still lacks efficient catalysts. In this work, Cu nanoparticles decorated juncus-derived carbon can be proposed as a high-active electrocatalyst for NO 2 −-to-NH 3 conversion, obtaining a high Faradaic efficiency of 93.2% and a satisfactory NH 3 yield of 523.5 μmol h−1 mg cat. −1. Density functional theory calculations were applied to uncover insightful understanding of internal catalytic mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] Effective removal of polybrominated diphenyl ethers (PBDEs) from the environment is essential for the ecosystem and human health. Reductive debromination of PBDEs by nanoscale zerovalent iron (nZVI) has become an important technology. However, the agglomeration and low persistence catalytic activity of nZVI particles have become urgent problems to be improved. Herein, we report the first application of a new organo-attapulgite (OA) supported Fe/Pd nanoparticles (OA-Fe/Pd) composite for decabromodiphenyl ether (BDE209) removal. BDE209 was efficiently removed using OA-Fe/Pd with a reaction rate that was 9.97 times greater than that of the nZVI due to the synergetic effect of support material OA and Pd loading. OA could prevent nZVI particles from agglomeration and adsorb BDE209 molecules to its surface. Pd could supply atomic hydrogen and also prevent the oxidation of nZVI particles. The degradation of BDE209 by OA-Fe/Pd was affected by many factors and followed pseudo first-order kinetics. The degradation of BDE209 by OA-Fe/Pd underwent a stepwise debromination manner with the H-transfer dominant mechanism. BDE209 (25 mg∙L-1) could be degraded to penta-BDEs to diphenyl ether (DE) by 3.0 g∙L-1 OA-Fe/Pd within 240 min under neutral condition. This study provides some inspiration for improving the removal efficiency of PBDEs with nZVI-based materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The development of efficient carbon-carbon cross-coupling catalysts with low noble metal amounts. • The Cu/C-700/Pd nanocomposite is obtained by loading trace Pd2+ onto carbon support derived from a novel mononuclear copper complex. • The Cu/C-700/Pd nanocomposite shows excellent catalytic activity and selectivity in Suzuki-Miyaura cross-coupling reaction, which implied a good synergistic effect in the bimetallic composite catalyst. • The bimetallic composite catalyst has excellent stability and recyclability. The development of efficient carbon–carbon cross-coupling catalysts with low noble metal amounts attracts much attention recently. Herein, a Cu/C-700/Pd nanocomposite is obtained by loading trace Pd2+ onto carbon support derived from a novel mononuclear copper complex, {[Cu(POP) 2 (Phen) 2 ]BF 4 }. The as-prepared nanomaterial features the facial structure of highly dispersed copper phosphide nanoparticles as well as Pd nanoparticles via neighboring Cu-Pd sites. The Cu/C-700/Pd nanocomposite shows excellent catalytic activity (99.73%) and selectivity in Suzuki-Miyaura cross-coupling reaction, at trace Pd loading (0.43 mol%). Compared with the reported palladium nano catalysts, its advantages are proved. The appealing gateway to this stable, innovative and recyclability, Cu/C-700/Pd nanostructure recommends its beneficial utilization in carbon–carbon coupling and other environmentally friendly processes. [ABSTRACT FROM AUTHOR]

Abstract: A straightforward approach to the synthesis of “clickable” thermoresponsive core cross-linked (CCL) nanoparticles was developed. This approach was based on reversible addition-fragmentation chain transfer (RAFT) radical cross-linking polymerization of styrene and divinylbenzene with azide-functionalized poly(N-isopropylacrylamide) (PNIPAM-N3) as macro chain transfer agent in a selective solvent. Spherical nanoparticles with a diameter of 12nm were obtained after 24h polymerization. When the lyophilized CCL nanoparticles were dispersed in THF, spherical nanoparticles were observed, confirming the stability of CCL nanoparticles. The transmission electron microscopy (TEM) studies demonstrated that spherical nanoparticles and wormlike structure coexisted in the aqueous solution. The CCL nanoparticles have a lower critical solution temperature (LCST) at about 29.6°C, a little lower than that of PNIPAM homopolymer. Biotin molecules were conjugated to the surface of CCL nanoparticles via “click” chemistry in aqueous media. After bioconjugation, the LCST shifted to 28.3°C. The bioavailability of biotin to protein avidin was evaluated by a 4′-hydroxyazobenzene-2-carboxylic acid/avidin (HABA/avidin) binding assay and TEM. [Copyright &y& Elsevier]

Abstract: An amphiphilic star block copolymer comprised of a hydrophobic PMMA block and a hydrophilic tri-arm poly(NIPAAm-co-DMAEMA) block was synthesized by copolymerization of NIPAAm and DMAEMA, with Ce4+ ions and tris(hydroxymethyl)methylamine as a redox initiatory system. The star copolymer undergoes self-assembly to the micellar nanoparticles with a core–shell structure and the thermo/pH dual-response, originated from the thermo-sensitivity of PNIPAAm and the pH-sensitivity of PDMAEMA. A fluorescence probe study showed the pH-dependent low CMCs (7.5 to 11.2 mg/L) of the micelles, confirming the formation of stable micelles. Morphological investigations showed that the blank and drug-loaded micelles both had spherical and uniform shapes. The sizes of the blank and drug-loaded nanoparticles were between 80 and 120 nm, depending on the given pH. The LCSTs of the star copolymer were determined to be 32 °C, 36.6 °C and 39.5 °C, corresponding to pH 5, pH 7.4 and pH 9, respectively, demonstrating a pH-dependent thermo-response. As a drug delivery, the micellar nanoparticles showed the dual-responsive release profiles in vitro, which were confirmed by the drug release studies. The obtained results showed the thermo-triggered accelerated release at pH 7.4, and the pH-triggered accelerated release at 37 °C, indicating the micelles nanoparticles would be a promising site-specific drug delivery for enhancing the accumulation of drug in targeting pathological areas. [Copyright &y& Elsevier]

Hybrid Pt/EMT nanomaterials in size of about 15–20 nm were synthesized by highly dispersing Pt nanoparticles (5–8 nm) on the support of ultrasmall EMT zeolite, which were utilized as peroxidase mimics for accurate detection of H 2 O 2 and glucose with a sensitive and reliable colorimetric assay, based on the catalytic oxidation of colorless TMB into blue ox-TMB using uniformly loaded Pt nanoparticles as active sites on microporous EMT zeolite with large surface area and pore volume. In past decade, Pt-based nanomaterials as peroxidase mimics have attracted much attention for H 2 O 2 and glucose detection. However, easy aggregation of Pt nanoparticles (Pt NPs) greatly decreases their peroxidase-like activity. In this work, novel Pt/EMT nanocomposites were prepared by uniformly loading Pt NPs (5–8 nm) onto the support of ultrasmall EMT zeolite (15–20 nm), a kind of low-silica microporous aluminosilicate material. The hybrid Pt/EMT nanomaterials could be well dispersed in water to form a homogeneous suspension, and were then utilized as a superior peroxidase-like catalyst for oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H 2 O 2). The optimal catalyst of 2.6Pt/EMT nanocomposite exhibited excellent catalytic performance toward H 2 O 2 and TMB than natural enzyme of horseradish peroxidase (HRP) by using a steady-state kinetic analysis based on the typical Michaelis-Menten kinetics theory. The peroxidase-like catalyst showed a promising activity in a wide pH and temperature range as well as the long-term stability. A facile and reliable colorimetric assay based on the peroxidase mimic of Pt/EMT nanocomposite was constructed for precise detection of H 2 O 2 and glucose in a wide linear range, with low limits of detection of 1.1 μM and 13.2 μM, respectively. Due to high selectivity to glucose against other sugars on the catalyst, the method was demonstrated to accurately measure the concentration of glucose in real samples including human blood serum and fruit juices, indicating a potential application of the Pt/EMT nanocomposites as a robust peroxidase mimic and a reliable biosensor in the fields of clinical diagnosis, pharmaceutical, food research and so on. [ABSTRACT FROM AUTHOR]

To explore alkaline fuel cells in practice, searching low-cost and efficient alternatives to Pt-based catalysts is urgent yet challenging for oxygen reduction reaction (ORR). Herein, Co 3 Fe 7 alloy nanoparticles wrapped in N -doped defect-rich carbon nanosheets (Co 3 Fe 7 /CNs) were synthesized at 800 °C by a one-step pyrolysis of the mixture (dicyandiamide, iron (II) phthalocyanine (FePc), cobalt (II) phthalocyanine (CoPc) and Fe 2 O 3), defined as Co 3 Fe 7 /CNs-800 for simplicity. The pyrolysis temperature and the dosages of dicyandiamide closely correlated to the ORR performance of the resultant catalysts in 0.1 M KOH solution. Significantly, the optimized Co 3 Fe 7 /CNs-800 exhibited encouraging onset potential (E onset = 0.97 V) and half-wave potential (E 1/2 = 0.85 V) in the alkaline media, surpassing commercial Pt/C (50 wt %, E onset = 0.96 V, E 1/2 = 0.84 V). This work provides a feasible strategy for developing efficient non-noble metal ORR electrocatalysts in the alkaline condition. [ABSTRACT FROM AUTHOR]

Ni@NTMCs was synthesized though a facile method, displaying a high removal efficiency (250 mg g−1) and stability in the acid solution, which is the best performance for the Ni based adsorbents in the environmental remediation. Nitrogen doped tubular magnetic carbons embedded with nickel nanoparticles (Ni@NTMCs) were prepared via a simple pyrolysis process and employed as the effective adsorbents for the Cr(VI) removal. Ni@NTMCs with as high as 10.63 at.% N doping exhibited the excellent Cr(VI) removal capacities of 24.4 and 250 mg g−1 in neutral and acidic solution, respectively. Adsorption kinetics and isotherm study revealed that the monolayer chemical adsorption was the rate-controlling step for the Cr(VI) removal. The high removal performance can be ascribed to the combination of adsorption and reduction reaction between Cr(VI) ions, and Ni nanoparticles. N dopant and edge carbons acted as the Cr(VI) adsorption site. The surface Ni nanoparticles mainly made contributions to the reduction process. The embedded Ni nanoparticles steadily provided magnetism for the separation and helpful for the recycles stability, showing a high acid corrosion resistance in this study. [ABSTRACT FROM AUTHOR]

To develop an injectable formulation and improve the stability of disulfiram (DSF), DSF was encapsulated into mixed nanoparticles (DSF-NPs) through a high-pressure homogenization method. The Flory-Huggins interaction parameters (χ FH ) were calculated to predict the miscibility between DSF and the hydrophobic core, resulting in PCL 5000 selected as the hydrophobic block to encapsulate the DSF, as PCL 5000 had a lower χ FH 3.39 and the drug loading of the nanoparticles prepared by mPEG 5000 -PCL 5000 was relatively higher. mPEG 5000 -PCL 5000 and PCL 5000 were blended to reduce the leakage of DSF during preparation, as well as increase the stability of the nanoparticles. The cargo-loading capacity of the nanoparticles was improved from 3.35% to 5.50% by reducing the crystallinity of the PCL nanoparticle core, and the crystallinity decreased from 51.13% to 25.15% after adding medium chain triglyceride (MCT). The DSF-NPs prepared by the above method had a small particle size of 98.1 ± 10.54 nm, with a polydispersity index (PDI) of 0.036, as well as drug loading of 5.50%. Furthermore, DSF-NPs containing MCT showed higher stability than DSF-NPs without MCT and DSF-sol (DSF dissolved in Cremophor EL and ethanol) in water and 90% plasma-containing PBS. The pharmacokinetics proved that DSF-NPs containing MCT enhanced the DSF concentration in the blood. Finally, DSF-NPs effectively inhibited H22 xenograft tumor growth in vivo. [ABSTRACT FROM AUTHOR]

Exploitation of lipid nanoparticles for oral delivery of nutrients and drugs is limited by their poor stability under gastrointestinal tract and low loading capacity, unless a high concentration of synthetic surfactants is formulated. The main objective of present study is to design a series of new formulations for solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) that are suitable for potential oral delivery applications, using natural biopolymers, i.e. sodium caseinate (NaCas) as emulsifier and pectin as coating, with minimal addition of a synthetic surfactant, Tween 80. Effects of pectin coating, concentration of Tween 80, thermal treatment (80 °C for 30 min), as well as two chemical cross-linkers on the particulate characteristics, stability, encapsulation efficiency, controlled release and drying feasibility were comprehensively investigated. The intermolecular interactions and cross-linking reactions were studied using Fourier transform infrared spectroscopy. Tween 80 at 0.15% (w/v) together with 0.15% (w/v) NaCas was proved effective to obtain stable cross-linked pectin-coated SLN (PSLN) under 200 nm with high loading capacity for curcumin, while NLC prepared under the same condition failed to pass storage stability test. The 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/ N- hydroxysuccinimide (EDC/NHS) cross-linked PSLN exhibited superior characteristics than glutaradehyde (GA) cross-linked PSLN, especially for the stability and controlled release under simulated gastrointestinal conditions, with curcumin studied as a model compound. The feasibility of both nano spray drying and freeze-drying technologies were both investigated to transform of colloidal lipid nanoparticles into dry powders. Our results demonstrated a novel strategy to prepare small and homogenous SLN with exceptional GI stability and high loading capacity as a potential oral delivery system. [ABSTRACT FROM AUTHOR]

The Yb 3+ and Er 3+ codoped orthorhombic LuF 3 rectangular nanocrystals (NCs) with the size of about 10 nm were synthesized by a facile and effective solvothermal process. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), upconversion (UC) luminescence spectra and decay curves were used to characterize the resulting samples. Compared with YF 3 and α-NaYF 4 NCs, owning the similar size and the same doping levels of Yb 3+ ions and Er 3+ ions as LuF 3 NCs, the green UC emission of LuF 3 NCs is 18.7 times and 5.1 times stronger than that of YF 3 and α-NaYF 4 NCs respectively; the red UC emission of LuF 3 NCs is 13.2 times and 0.6 times stronger than that of YF 3 and α-NaYF 4 NCs respectively. Under 980 nm wavelength excitation, the decay curves of both 4 S 3/2 → 4 I 15/2 transition and 4 F 9/2 → 4 I 15/2 transition exhibit a single exponential function, resulting from the fast energy migrations among Yb 3+ ions caused by the high concentration of Yb 3+ ions (20 mol%). Meanwhile, at relatively low power density, the slopes of the linear plots between log(I) and log(P) for green UC and red UC are 1.7 and 1.9 respectively, which are less than 2 due to the quenching of the thermal effect, indicating a two-photon process for them. At high power density, the slopes are decreased caused by the saturation effect. In addition, we proved the existence of the thermal effect by the pump power dependence of the intensity ratio of 2 H 11/2 → 4 I 15/2 transition to 4 S 3/2 → 4 I 15/2 transition. [ABSTRACT FROM AUTHOR]

A MnO 2 nanosheet (MnO 2 -NS) suspension was prepared from tetramethylammonium hydroxide (TMA⋅OH), H 2 O 2 , and MnCl 2 ⋅4H 2 O, and its efficiency for Cd(II) removal from aqueous solutions was investigated. The maximum adsorption capacity of the MnO 2 -NS for Cd(II) was evaluated to be about 348 mg/g, which is thus far the highest value reported for MnO 2 at pH 6.0. This high adsorption capacity is attributed to efficient ion exchange. X-ray photoelectron spectroscopy (XPS) revealed that Cd(II) was adsorbed on MnO 2 as CdO and Cd(OH) 2 . After Cd(II) adsorption, the suspended MnO 2 -NS aggregated and precipitated within 5.0 min from solution. Therefore, dispersive MnO 2 -NS can be used to remove Cd(II) from wastewater rapidly and with high efficiency. [ABSTRACT FROM AUTHOR]

Allyl isothiocyanate (AITC), an organosulfur compound in cruciferous vegetables, is a natural antimicrobial and potential chemopreventive agent. However, the instability of AITC in aqueous systems restrains its applications. In this study, oil-in-water AITC nanoemulsion was prepared by the emulsion inversion point (EIP) method, aiming at improving the aqueous stability of AITC. The optimal hydrophilic–lipophilic balance (HLB op ) value of surfactants containing Tween 80 and Span 80 was established at 11.0–13.0, yielding nanodroplets with diameters of 137–215 nm. The mechanism of droplet formation within the HLP op region was discussed in terms of the possible structure of adsorbed surfactant layers at the oil–water interface in multiple emulsion droplets. In a 6.5-month storage test, the droplet sizes and the count rates (intensity of scattered light) of nanoemulsions decreased only slightly by 4–13% (depending on surfactant-to-oil ratio), even in highly diluted status, indicating the desirable stability of the nanoemulsions. Moreover, the nanoemulsion demonstrated superior protection against AITC degradation (78% remaining after 60 d at 30 °C), compared with protein nanoparticles as well as non-encapsulated aqueous dispersion. This work shows for the first time that AITC can be formulated into nanoemulsions and thus obtains satisfactory aqueous solubility and chemical stability. [ABSTRACT FROM AUTHOR]