Crosslinked polymer nanocapsules

Polymer nanocapsules (PNCs) are an important class of nanocarriers, but applications of conventional non‐crosslinked PNCs have been significantly limited because they are susceptible to environmental conditions. Synthesis and applications of crosslinked PNCs (CPNCs) with robust covalently stabilized nanostructures have attracted great interest over the past decade. Three major categories of template synthesis approaches for the preparation of CPNCs have been established: (1) cavitation of shell‐crosslinked nanostructures, (2) vesicle‐based crosslinking and (3) emulsion interfacial crosslinking. This article provides a critical and comprehensive review of these approaches. Several special cases of the synthesis of CPNCs are also reviewed. © 2016 Society of Chemical Industry     

Xanthate‐mediated polymerization of styrene on hyperbranched polyethylenimine: Synthesis,characterization, and guest‐encapsulating property

Hyperbranched polyethylenimine (HPEI) is a highly polar, multifunctional polymer bearing active amines throughout its globular structure. In this article, the amino protons, which were incompatible with living radical polymerization techniques, were alkylated with propylene oxide, leading to tertiary amines and hydroxyls, and part of the hydroxyl groups were further transformed into xanthate groups. The HPEI‐xanthate could mediate the polymerization of styrene, leading to a star‐like, multiarm amphiphilic polymer. It was found that the polymerization was a hybrid of living and conventional radical processes. The resulting amphiphilic, core‐shell‐structured polymer existed as a unimolecular micelle (UIM) in apolar solvent and could irreversibly encapsulate water‐soluble anionic dyes. At high pH, the encapsulated dyes could be partly released. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Multifunctional Carbon–Silica Nanocapsules with Gold Core for Synergistic Photothermal and Chemo‐Cancer Therapy under the Guidance of Bimodal Imaging

Carbon‐based nanomaterials have been developed for photothermal cancer therapy, but it is still a great challenge to fabricate their multifunctional counterparts with facile methods, good biocompatibility and dispersity, and high efficiency for cancer theranostics. In this work, an alternative multifunctional nanoplatform is developed based on carbon–silica nanocapsules with gold nanoparticle in the cavity (Au@CSN) for cancer theranostics. The encapsulated chemodrug doxorubicin can be released from the Au@CSN with mesoporous and hollow structure in a near‐infrared light and pH stimuli‐responsive manner, facilitating spatiotemporal therapy to decrease off‐target toxicity. The nanocapsules with efficient photothermal conversion and excellent biocompatibility achieve a synergistic effect of photothermal and chemotherapy. Furthermore, the nanocapsules can act as a multimodal imaging agent of computed tomography and photoacoustic tomography imaging for guiding the therapy. This new design platform can provide a promising strategy for precise cancer theranostics.     

微乳液聚合法制备天然除虫菊酯纳米胶囊

研究用微乳液聚合法制备以甲基丙烯酸甲酯和苯乙烯共聚体为囊壁,以天然除虫菊酯为囊芯的纳米胶囊。考察了乳化剂的量,壳芯比对纳米胶囊的粒径、粒径分布和结构的影响。当在乳化剂浓度约为10.6%的情况下,微乳液比较稳定,且当单体和农药比率为1∶1时,将得到包覆结构和粒径分布较为理想的天然除虫菊酯纳米胶囊。     

胶体体系中合成纳米胶囊的研究进展

综述了在不同胶体体系(乳液、双重乳液、微乳等)中合成纳米胶囊的研究工作，介绍了纳米胶囊新型的合成手段，包括界面聚合法、界面沉积法、复相乳液溶剂挥发法、聚电解质的逐步沉积法和微乳聚合法等不同的制备方法。并从纳米胶囊的粒径、包裹率、Zeta电位、热敏性和酸碱敏感性等方面分析了纳米胶囊的物理化学性能。     

天然除虫菊素和阿维菌素纳米胶囊结构表征及杀虫活性测定

用微乳液聚合法制备了天然除虫菊素和阿维菌素纳米胶囊,产品透明稳定。用激光粒度仪和透射电子显微镜对纳米胶囊的粒度和结构进行了测试和表征。结果表明,纳米胶囊颗粒较小,都在400nm以下,且分布均匀。室内杀虫活性试验证明了天然除虫菊素和阿维菌素纳米胶囊比相应的原药对蚜虫有更好的防治效果,有很好的缓释性和持效性,在喷药45d以后,其相对防效仍然维持在80%以上。     

复配型乳化剂在氯氰菊酯纳米胶囊制备中的应用

实验将可聚合乳化剂烯丙氧基壬基酚聚氧乙烯(10)醚硫酸铵(DNS-86)和非离子型乳化剂OP-10复配,经微乳液聚合法制备了氯氰菊酯纳米胶囊。考察了乳化剂用量、2种乳化剂的配比、壳芯比及聚合温度对纳米胶囊的粒径和粒径分布的影响。结果表明,当w(乳化剂)=9.29%,m(DNS-86):m(OP-10)=4:3,m(农药):m(单体)=3:2.5,聚合温度为60℃时,可得到包裹结构和粒径分布较理想的氯氰菊酯纳米胶囊。     

A New Process for Drug Loaded Nanocapsules Preparation Using a Membrane Contactor

ABSTRACT

In this paper, we describe a new process for the preparation of drug loaded nanocapsules using a membrane contactor which may be scaled up for industrial applications. Nanocapsules are prepared according to the nanoprecipitation method. The organic phase (solvent, polymer, oil, and drug) is pressed through the pores of an ultrafiltration membrane via the filtrate side. The aqueous phase (water and surfactant) circulates inside the membrane module, and sweeps away the nanocaspules forming at the pore outlets. Two model drugs are selected for the preparation of drug loaded nanocapsules: indomethacin and vitamin E. It is shown that indomethacin loaded nanocapsules with a mean diameter of 240 nm and vitamin E loaded nanocapsules with a mean diameter of 230 nm are obtained with a 150,000 daltons ultrafiltration membrane, a transmembrane pressure of 3 bar, and a crossflow rate of 1.7 m.s^{? 1}. High fluxes are also obtained (around 0.6 m³/h.m²), leading to the preparation of 1.8 10^{? 3} m³ drug loaded nanocapsules in 8 min. The advantage of this membrane contactor compared to other processes for drug loaded nanocapsules preparation is shown to be its scale-up ability.     

A multiple emulsion method for loading 5‐fluorouracil into a magnetite‐loaded nanocapsule: a physicochemical investigation

The preparation of 5‐fluorouracil (5‐FU) loaded poly(lactic‐co‐glycolic acid) (PLGA) biodegradable nanocapsules containing magnetite nanoparticles was studied through the modified multiple emulsion solvent evaporation method for magnetically controlled delivery of anticancer drugs. The morphology and size distribution of the prepared magnetite/PLGA nanocapsules were investigated by transmission and scanning electron microscopy. The micrographs showed that the magnetic nanocapsules were almost spherical in shape and their mean diameter was in the nanometer range with a narrow size distribution. Fourier transform infrared and ultraviolet–visible spectroscopy confirmed incorporation of 5‐FU molecules into the PLGA matrix. The magnetite content was assessed by thermogravimetric and magnetometry analysis and the results showed a magnetite content of 35 wt% with high magnetic responsivity. Magnetometry measurements showed superparamagnetic properties of the magnetic nanocapsules with a saturation magnetization of 13.7 emu g^?1. Such biodegradable magnetic nanocapsules could be considered as an appropriate choice for drug targeting. Furthermore, the influence of some important processing parameters such as PLGA concentration, initial loading of 5‐FU and poly(vinyl alcohol) concentration on drug content, encapsulation efficiency and in vitro drug release kinetics was investigated and optimized. The drug content and encapsulation efficiency of the magnetic nanocapsules were 4–7 wt% and 60%–80%, respectively, and the nanocapsules demonstrated controlled release of 5‐FU at 37 °C in a buffer solution. All samples exhibited a burst release at the initial stage and this burst release showed its close dependence on the formulation parameters. Copyright © 2012 Society of Chemical Industry