Colloidal micelles of block copolymers as nanoreactors,templates for gold nanoparticles,and vehicles for biomedical applications

Target drug delivery methodology is becoming increasingly important to overcome the shortcomings of conventional drug delivery absorption method. It improves the action time with uniform distribution and poses minimum side effects, but is usually difficult to design to achieve the desire results. Economically favorable, environment friendly, multifunctional, and easy to design, hybrid nanomaterials have demonstrated their enormous potential as target drug delivery vehicles. A combination of both micelles and nanoparticles makes them fine target delivery vehicles in a variety of biological applications where precision is primarily required to achieve the desired results as in the case of cytotoxicity of cancer cells, chemotherapy, and computed tomography guided radiation therapy.     

Control of reactions between surfactant reagents in miniemulsions. Surface nanoreactors

Emulsions may be used to speed up reactions of surface-active reagents. In this paper, a theoretical analysis of a simple catalytic reaction (A + B → P + B) is performed, where the substrate A in the presence of the catalyst B in an emulsion is converted into the product P, and both the substrate A and the catalyst B are surfactants. It was shown that, because molecules A and B are concentrated in surface layers of the emulsion, these layers act as nanoreactors ensuring a significant acceleration of the catalytic reaction within a certain range of emulsion droplet sizes. The reaction rate depends significantly on the emulsion droplet’s size and there exists an optimal droplet size at which the reaction acceleration is maximal. If the product of the reaction is not surface-active, the reaction rate can remain practically unchanged up to virtually complete substrate conversion. Besides, it was shown that the Michaelis–Menten-type dependence of the reaction rate on the substrate concentration (i.e., the increase in the rate with subsequent saturation) can be observed in the system under consideration.     

反应性嵌段共聚物自组装制备无机纳米粒子研究进展

具有"核-壳"结构的嵌段共聚物胶束具有广泛的用途.本文介绍了反应性嵌段共聚物的自组装技术应用于制备具有独特的光、电、磁等以及催化特性的无机纳米粒子,特别是介绍了近年来在制备纳米贵金属粒子的研究进展.     

In-situ formation of silver nanoparticles stabilized by amphiphilic star-shaped copolymer and their catalytic application

Silver nanoparticles (Ag NPs) were prepared via in situ reduction of silver nitrate (AgNO₃) using polymeric micelles as nanoreactors without any additional reductant. The micelles were constructed from the amphiphilic star-shaped copolymer composed of poly(?-caprolactone) (PCL) segment, 2-(dimethylamino)ethyl methacrylate (DMAEMA or DMA) units and oligo(ethylene glycol)monomethyl ether methacrylate (OEGMA or OEG) units. The Ag NPs stabilized by those star-shaped copolymers were characterized using UV-vis spectrum, DLS, TEM and FTIR. It confirmed that PDMAEMA exhibited the reducing property unless pH was above 7. The Ag NPs were sphere-like with a diameter of 10-20 nm, which was independent of the architecture of the copolymer and AgNO₃ concentration. Furthermore, the catalytic activity of these Ag NPs was investigated by monitoring the reduction of p-nitrophenol (4-NP) by NaBH₄. The result showed that the Ag NPs formed by coordination reduction can be effectively applied in catalytic reaction.     

CoP@SiO2nanoreactors: A core-shell structure for efficient electrocatalytic oxygen evolution reaction

Metallic phosphides as a crucial class of metal-like compounds show high electric conductivity and electrochemical properties. It is of significant benefit to understanding the relationship between the electrocatalytic performance and phosphating degree of precursors. In this work, using Co₃O₄@SiO₂ as precursor, core-shell structured CoP@SiO₂ nanoreactors with outstanding oxygen evolution reaction performance were synthesized through a facile calcination method. The electrocatalytic performance of CoP@SiO₂ modified electrode that treated with 500 mg NaH₂PO₂ was greatly enhanced. The obtained product displays a low overpotential of 280 mV at a current density of 10 mA/cm² and a Tafel value 89 mV/dec in alkaline conditions. The easy available CoP@SiO₂ with outstanding catalytic performance and stability possesses huge potential in future electrochemical applications.     

Size control of spherical metallic nanocrystals

In this review, we show that the use of AOT reverse micelles favors the formation of spherical metallic nanomaterials, magnetic or not, such as cobalt and copper. The size is controlled by varying different parameters like the water content of the micelles, the intermicellar interactions, the capping with the AOT surfactant and the reducing agent concentration. As expected theoretically, the change in size of copper nanocrystals induces changes in their optical properties. By controlling both the size and the size distribution of cobalt nanocrystals, well-defined, two-dimensional superlattices can spontaneously form.     

纳米反应器的研究进展

介绍了近年来见诸于研究中的四种纳米反应器，分别是反相微乳液，嵌段共聚物，多孔材料和层状硅酸盐，总结了这些纳米反应器的研究进展并讨论了它们的应用前景。     

“蛋黄-蛋壳”结构纳米反应器的设计、调控及在锂硫电池正极中的应用研究

锂硫电池具有理论能量密度高等优势,被认为是最有前景的一类新型二次电池.硫正极存在硫和硫化锂的导电性差、可溶性多硫化物的扩散/穿梭、循环过程中硫的体积膨胀以及氧化还原过程慢等问题,严重制约着电池的活性和循环稳定性.设计“蛋黄-蛋壳”结构纳米反应器应用于锂硫电池正极,可通过调控其“蛋黄”、“蛋壳”和“空腔”结构缓解充放电过程中电极的体积变化,为离子/电子输运提供快速通道,强化对多硫化物的吸附和催化转换作用等,进而提高电极的活性和循环性能,有利于推进锂硫电池的商业化进程.本文总结了“蛋黄-蛋壳”结构纳米反应器的设计和调控策略,包括单核-单壳、单核-多壳、多核-单壳以及多核-多壳等,并结合锂硫电池的工作特点和目前应用存在的问题,对未来发展前景进行了展望.     

Nanoreactors derived from silica-protection-assisted metal-organic framework

The construction of highly stable and regular nanoreactors is a major challenge. In this work, we use a facile template protection method to obtain ZIF-67@SiO₂ (JS) and to encapsulate metal oxide nanoparticles (Co₃O₄) into nanoreactors (SiO₂). ZIF-67 crystals provide a cobalt species; SiO₂ was first used as a protective layer of ZIF-67 and then as a nanoreactor for metastable metal oxide nanoparticles. On this basis, Co₃O₄@SiO₂ with dodecahedron morphology were synthesized by calcining JS at different temperatures, followed by a hydrothermal reaction to obtain Co₃(OH)₄Si₂O₅. Subsequently, CoS_x and CoP-SiO₂ were fabricated through sulfuration and phosphorization. The results in this work show that nanoreactors derived from metal-organic frameworks (MOFs) with a rational structure have broad development prospects.