金属有机纳米粒的制备及其在高强度聚焦超声治疗小鼠肝癌中的增效作用

目的制备一种金属有机纳米粒,并探究其在高强度聚焦超声(HIFU)治疗肿瘤中的增效作用。方法制备二氧化锰(MnO_(2))纳米粒,利用物理吸附法将葡萄糖氧化酶(GOD)、MnO_(2)、三价铁离子(Fe^(3+))与抗癌药物阿霉素(DOX)自组装形成GODMnO_(2)-Fe^(3+)-DOX纳米粒(GMFD NPs)并进行表征。建立HepG2肝癌细胞荷瘤裸鼠模型,随机分为生理盐水+HIFU和GMFD NPs+HIFU组。HIFU治疗声功率为90W,治疗总时间为3 s。观察HIFU辐照前后肿瘤灰度值变化。HIFU辐照结束24 h后观察肿瘤组织凝固性坏死情况,收集肿瘤组织,苏木精-伊红染色法(HE染色)观察各组织的形态结构变化。结果成功制备GMFD NPs,其粒径为131.23±0.84 nm,表面电位为+21.87±1.72 mV。其中DOX的载药率为40.18%,在酸性环境中,DOX在4 h内释放的药物超过77.2%。体内动物实验结果表明HIFU辐照后,GMFD NPs组灰度增强(25.5±4.50)明显高于生理盐水组(18.7±3.85),差异具有统计学意义(P=0.04)、凝固性坏死体积GMFD NPs组(105.80±1.21 mm^(3))明显大于生理盐水组(38.02±0.34 mm^(3))、能效因子(EEF)GMFD NPs组(1.79)明显低于生理盐水组(4.97),差异具有统计学意义(P<0.001)。结论制备的GMFD NPs可增强HIFU对瘤鼠肿瘤组织的消融效果并释放抗癌药物DOX以治疗残留的肿瘤组织。

Ni@Pd core-shell nanoparticles supported on a metal-organic framework as highly efficient catalysts for nitroarenes reduction

Ni@Pd core-shell nanoparticles with a mean particle size of 8–9 nm were prepared by solvothermal reduction of bivalent nickel and palladium in oleylamine and trioctylphosphine.Subsequently,the first-ever deposition of Ni@Pd core-shell nanoparticles having different compositions on a metal-organic framework（MIL-101）was accomplished by wet impregnation in n-hexane.The Ni@Pd/MIL-101 materials were characterized by powder X-ray diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,and energy-dispersive X-ray spectroscopy and also investigated as catalysts for the hydrogenation of nitrobenzene under mild reaction conditions.At 30 °C and 0.1 MPa of H2 pressure,the Ni@Pd/MIL-101 gives a TOF as high as 375 h–1 for the hydrogenation of nitrobenzene and is applicable to a wide range of substituted nitroarenes.The exceptional performance of this catalyst is believed to result from the significant Ni-Pd interaction in the core-shell structure,together with promotion of the conversions of aromatics by uncoordinated Lewis acidic Cr sites on the MIL-101 support.

Ni-based catalysts derived from a metal-organic framework for selective oxidation of alkanes

Ni nanoparticles embedded in nitrogen-doped carbon（Ni@C-N） materials were prepared by ther-molysis of a Ni-containing metal-organic framework （Ni-MOF） under inert atmosphere. The as-synthesized Ni@C-N materials were characterized by powder X-ray diffraction, N_2 adsorp-tion-desorption analysis, scanning electron microscopy, transmission electron microscopy, atomic absorption spectroscopy, and X-ray photoelectron spectroscopy. The MOF-derived Ni-based mate-rials were then examined as heterogeneous catalysts for the oxidation of alkanes under mild reac-tion conditions. The Ni@C-N composites displayed high activity and selectivity toward the oxidation of a variety of saturated C–H bonds, affording the corresponding oxidation products in good-to-excellent yields. Furthermore, the catalysts could be recycled and reused for at least four times without any significant loss in activity and selectivity under the investigated conditions.

Metal–organic-framework-based catalysts for hydrogenation reactions

Metal-organic-framework （MOF）-based materials with novel physicochemical properties have emerged as promising catalysts for various hydrogenation reactions. In addition to metal clusters and multifunctional organic ligands, MOF-based catalysts can incorporate other functional species, and thus provide various active sites for hydrogenation processes. The structural properties of the catalysts play significant roles in enhancing the interactions among the reactants, products, and catalytic sites, which can be rationally designed. Because of the synergistic effects between the ac-tive sites and the structural properties, MOF-based catalysts can achieve higher activities and selec- tivities in hydrogenation reactions than can be obtained using traditional heterogeneous catalysts. This review provides an overview of recent developments in MOF-based catalysts in the hydro-genation of alkenes, alkynes, nitroarenes, cinnamaldehyde, furfural, benzene, and other compounds. Strategies for improving the catalytic performances of MOF-based catalysts are discussed as well as the different active sites and structural properties of the catalysts.

Hierarchically porous S-scheme CdS/UiO-66 photocatalyst for efficient 4-nitroaniline reduction

Unveiling the pore-size performance of metal organic frameworks(MOFs)is imperative for controllable design of sophisticated catalysts.Herein,UiO-66 with distinct macropores and mesopores were intentionally created and served as substrates to create advanced CdS/UiO-66 catalysts.The pore size impacted the spatial distribution of CdS nanoparticles(NPs):CdS tended to deposit on the external surface of mesoporous UiO-66,but spontaneously penetrated into the large cavity of macroporous UiO-66 nanocage.Normalized to unit amount of CdS,the photocatalytic reaction constant of macroporous CdS/UiO-66 over 4-nitroaniline reduction was~3 folds of that of mesoporous counterpart,and outperformed many other reported state-of-art CdS-based catalysts.A confinement effect of CdS NPs within UiO-66 cage could respond for its high activity,which could shorten the electron-transport distance of NPs-MOFs-reactant,and protect the active CdS NPs from photocorrosion.The finding here provides a straightforward paradigm and mechanism to rationally fabricate advance NPs/MOFs for diverse applications.

Highly selective hydrogenation of furfural to tetrahydrofurfuryl alcohol over MIL-101(Cr)-NH_2 supported Pd catalyst at low temperature

An efficient heterogeneous catalyst,Pd@MIL‐101(Cr)‐NH2,is prepared through a direct pathway of anionic exchange followed by hydrogen reduction with amino‐containing MIL‐101as the host matrix.The composite is thermally stable up to350°C and the Pd nanoparticles uniformly disperse on the matal organic framework(MOF)support,which are attributed to the presence of the amino groups in the frameworks of MIL‐101(Cr)‐NH2.The selective hydrogenation of biomass‐based furfural to tetrahydrofurfuryl alcohol is investigated by using this multifunctional catalyst Pd@MIL‐101(Cr)‐NH2in water media.A complete hydrogenation of furfural is achieved at a low temperature of40°C with the selectivity of tetrahydrofurfuryl alcohol close to100%.The amine‐functionalized MOF improves the hydrogen bonding interactions between the intermediate furfuryl alcohol and the support,which is conducive for the further hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol in good coordination with the metal sites.

Synthesis of Cerium Doped Zirconium-Based Metal-Organic Framework Nanoparticles and Their Photocatalytic Performance for Carbon Dioxide Cycloaddition

Cerium-doped zirconium-based NH_(2)-UiO-66 nanoparticles were synthesized in ionic liquid 1-butyl-3-methylimidazolium acetate at room temperature.The crystal structure and morphology were studied using X-ray diffraction,infrared spectroscopy,scanning electron microscopy and transmission electron microscopy.The valence state and distribution of elements in the obtained materials were examined using X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy.Catalytic performance studies show that the cerium-doped NH_(2)-UiO-66 exhibits improved catalytic efficiency in the cycloaddition reaction of 1,2-butylene oxide and carbon dioxide than pure NH_(2)-UiO-66.Studies on the photoelectric properties indicate that the cerium-doped NH_(2)-UiO-66 catalyst possesses strong photocurrent response,low interfacial charge transfer resistance,narrow band gap,and low flat band potential.This work provides a new approach of synthesizing high-performance catalyst for photocatalytic CO_(2) cycloaddition.

Recent advances in plasmonic organic photovoltaics

Light trapping based on the localized surface-plasmon resonance(LSPR)effect of metallic nanostructures is a promising strategy to improve the device performance of organic solar cells(OSCs).We review recent advances in plasmonic-enhanced OPVs with solution-processed metallic nanoparticles(NPs).The different types of metallic NPs(sizes,shapes,and hybrids),incorporation positions,and NPs with tunable resonance wavelengths toward broadband enhancement are systematically summarized to give a guideline for the realization of highly efficient plasmonic photovoltaics.

In-situ characterization of metal nanoparticles and their organic coatings using laser-vaporization aerosol mass spectrometry

The development of methods to produce nanoparticles with unique properties via the aerosol route is progressing rapidly. Typical characterization techniques extract particles from the synthesis process for subsequent offiine analysis, which may alter the particle characteristics. In this work, we use laser-vaporization aerosol mass spectrometry （LV-AMS） with 70-eV electron ionization for real-time, in-situ nanoparticle characterization. The particle characteristics are examined for various aerosol synthesis methods, degrees of sintering, and for controlled condensation of organic material to simulate surface coating/functionalization. The LV-AMS is used to characterize several types of metal nanoparticles （Ag, Au, Pd, PdAg, Fe, Ni, and Cu）. The degree of oxidation of the Fe and Ni nanoparticles is found to increase with increased sintering temperature, while the surface organic-impurity content of the metal particles decreases with increased sintering temperature. For aggregate metal particles, the organic-impurity content is found to be similar to that of a monolayer. By comparing different equivalent-diameter measurements, we demonstrate that the LV-AMS can be used in tandem with a differential mobility analyzer to determine the compactness of synthesized metal particles, both during sintering and during material addition for surface functionalization. Further, materials supplied to the particle production line downstream of the particle generators are found to reach the generators as contaminants. The capacity for such in-situ observations is important, as it facilitates rapid response to undesired behavior within the particle production process. This study demonstrates the utility of real-time, in-situ aerosol mass spectrometric measurements to characterize metal nanoparticles obtained directly from the synthesis process line, including their chemical composition, shape, and contamination, providing the potential for effective optimization of process operating parameters.