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排序方式: 共有249条查询结果,搜索用时 31 毫秒
81.
82.
AbstractDevelopment of novel supported catalysts with high activity and stability is still a challenge. In this study, the Au-polydopamine (Au-PDA) hollow microcapsules with Au nanoparticles embedded into the PDA microcapsule shell have been synthesized through a simple template-induced covalent assembly method, where polystyrene (PS) nanospheres were used as templates to form core/shell structured PS/Au-PDA composites, followed by core removal through tetrahydrofuran etching. Their morphology and composition were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), UV-Vis spectrophotometer and X-ray diffraction (XRD), respectively. Results showed that the Au-PDA microcapsules possessed well-fined hollow structure and uniform sizes with inner diameter of about 385?nm, shell thickness of about 30?nm, and Au nanoparticles with diameter of about 17?nm incorporated. The catalytic performance of Au-PDA hollow microcapsules was evaluated through the reduction of methylene blue (MB) dye with NaBH4 as a reducing agent. Compared to PDA/Au composites with Au nanoparticles loaded on the surface of PDA microspheres, as-prepared Au-PDA hollow microcapsules show good stability and recyclability in the catalytic experiments as the Au nanoparticles were firmly wrapped in PDA matrix, which makes the Au-PDA hollow microcapsules a practicable catalyst candidate for advanced catalytic systems. 相似文献
83.
目的:建立蜂胶铬软胶囊质量控制的方法。方法采用浓硝酸-过氧化氢混合液微波消解样品,火焰原子吸收光谱法测定蜂胶铬软胶囊中铬含量。结果铬元素在0.4~2.5 mg· L-1范围内线性关系良好,样品铬测定值为49.92μg/粒,相对标准偏差为3.29%。茶叶标准物质( GSB-7)中铬元素的测定值与认定值相吻合。结论实验表明,方法简单、准确、可行,可作为蜂胶铬软胶囊中铬的检测方法。 相似文献
84.
We are reporting a novel green approach to incorporate silver nanoparticles (NPs) selectively in the polyelectrolyte capsule shell for remote opening of polyelectrolyte capsules. This approach involves in situ reduction of silver nitrate to silver NPs using PEG as a reducing agent (polyol reduction method). These nanostructured capsules were prepared via layer by layer (LbL) assembly of poly(allylamine hydrochloride) (PAH) and dextran sulfate (DS) on silica template followed by the synthesis of silver NPs and subsequently the dissolution of the silica core. The size of silver nanoparticles synthesized was 60±20 nm which increased to 100±20 nm when the concentration of AgNO(3) increased from 25 mM to 50 mM. The incorporated silver NPs induced rupture and deformation of the capsules under laser irradiation. This method has advantages over other conventional methods involving chemical agents that are associated with cytotoxicity in biological applications such as drug delivery and catalysis. 相似文献
85.
Dr. Michael L. Singleton Geert Pirotte Dr. Brice Kauffmann Dr. Yann Ferrand Dr. Ivan Huc 《Angewandte Chemie (International ed. in English)》2014,53(48):13140-13144
The postsynthetic modulation of capsules based on helical aromatic oligoamide foldamers would be a powerful approach for controlling their receptor properties without altering the initial monomer sequences. With the goal of developing a method to increase the size of a cavity within a helix, a single‐helical foldamer capsule was synthesized with a wide‐diameter central segment that was designed to intercalate with a second shorter helical strand. Despite the formation of stable double‐helical homodimers (Kdim>107 M ?1) by the shorter strand, when it was mixed with the single‐helical capsule sequence, a cross‐hybridized double helix was formed with Ka>105 M ?1. This strategy makes it possible to direct the formation of double‐helical heterodimers. On the basis of solution‐ and solid‐state structural data, this intercalation resulted in an increase in the central‐cavity size to give a new interior volume of approximately 150 Å3. 相似文献
86.
Katrin‐Stephanie Tücking Verena Grützner Ronald E. Unger Holger Schnherr 《Macromolecular rapid communications》2015,36(13):1248-1254
The synthesis of novel amphiphilic hyaluronic acid (HYA) and poly(lactic acid) (PLA) block copolymers is reported as the key element of a strategy to detect the presence of pathogenic bacterial enzymes. In addition to the formation of defined HYA‐block‐PLA assemblies, the encapsulation of fluorescent reporter dyes and the selective enzymatic degradation of the capsules by hyaluronidase and proteinase K are studied. The synthesis of the dual enzyme‐responsive HYA‐b‐PLA is carried out by copper–catalyzed Huisgen 1,3‐dipolar cycloaddition. The resulting copolymers are assembled in water to form vesicular structures, which are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering (DLS), and fluorescence lifetime imaging microscopy (FLIM). DLS measurements show that both enzymes cause a rapid decrease in the hydrodynamic diameter of the nanocapsules. Fluorescence spectroscopy data confirm the liberation of encapsulated dye, which indicates the disintegration of the capsules and validates the concept of enzymatically triggered payload release. Finally, cytotoxicity assays confirm that the HYA‐b‐PLA nanocapsules are biocompatible with primary human dermal microvascular endothelial cells. 相似文献
87.
毛细管气相色谱法测定速效伤风胶囊中对乙酰氨基酚、咖啡因、马来酸氯苯那敏的含量 总被引:3,自引:0,他引:3
用5%Ph-Me-Silicone毛细管色谱柱,FID,二阶程序升温,以正十六烷作为内标物测定速效伤风胶囊中对乙酰氨基酚、咖啡因、马来酸氯苯那敏的含量。浓度线性范围:对乙酰氨基酚4~20g/L,咖啡因0.084~0.42g/L,马来酸氯苯那敏0.15~0.75g/L。平均回收率(n=5):对乙酰氨基酚99.62%(RSD=0.44%)咖啡因96.46%(RSD=1.32%),马来酸氯苯那敏98.55%(RSD=0.65%)。 相似文献
88.
Dr. Jiangping Xu Dr. Jun Li Yi Yang Dr. Ke Wang Nan Xu Dr. Jingyi Li Dr. Ruijing Liang Prof. Lei Shen Prof. Xiaolin Xie Prof. Juan Tao Prof. Jintao Zhu 《Angewandte Chemie (International ed. in English)》2016,55(47):14633-14637
Although high‐boiling non‐solvent induced macrophase separation in emulsion droplets has been widely applied for the fabrication of polymeric capsules, precise control of their structures remains a great challenge. Herein, block copolymer capsules with tunable shell structures were fabricated by employing a non‐solvent as a liquid template in emulsion droplets. The properties of the non‐solvents dictate the phase separation sequence in the droplets and the capsule formation mechanism. Two different pathways for capsule formation were observed, and could be applied to predict the shell structure. The structured capsules could be transformed into mesoporous capsules, which demonstrated an intriguing structure‐dependent release behavior. Capsules with spherical shell structures displayed the best permeability, while those with lamellar shell structures showed the slowest release, but with a stepwise profile. After loading with an anticancer drug, different capsules induced different apoptosis ratios in cancer cell studies. 相似文献
89.
Hongyan Pei Yanyan Bai Jianman Guo Zhiliang Gao Qiong Dai Qun Yu Jiwei Cui 《中国化学快报》2020,31(2):505-508
Over the past two decades,layer-by-layer(LbL) assembly of micro/nanocapsules has been of interest for the investigation of bio-nano interactions to explore bio-applications,such as drug delivery.The choice of an appropriate template that can be easily dissolved under mild conditions is one of the challenges for the assembly of LbL capsules.Herein,we report the engineering of LbL capsules with tunable morphologies using cuprous oxide(Cu_2O) particles as templates.Cu_2O particles with cubic,tetradecahedral or spherical morphologies were synthesized via hydrothermal processes,which can be dissolved under mild condition(e.g.,sodium thiosulfate solution).The influence of capsule morphologies on cell association was investigated,which indicates that LbL capsules with cubic geometry promoted cell association up to 4 and 9-fold than tetradecahedral and spherical capsules,respectively.The reported method provides a new avenue for the assembly of LbL capsules with different morphologies,which has the potential for better understanding of biological interactions of LbL capsules. 相似文献
90.