Guo Jia, Wang Changchun, Mao Weiyong, Yang Wuli, Liu Changjia, Chen Jiyao
Key Laboratory of Molecular Engineering of Polymers (Minster of Education) and Department of Macromolecular Science, Fudan University, Shanghai 200433, People's Republic of China.
Nanotechnology. 2008 Aug 6;19(31):315605. doi: 10.1088/0957-4484/19/31/315605. Epub 2008 Jun 24.
In this paper, we present a facile and robust approach to synthesize multifunctional organic/inorganic composite microspheres with chitosan-poly(methacrylic acid) (CS-PMAA) shells and cadmium tellurium/iron oxide nanoparticle cores. Due to the strong electrostatic interaction between the negatively charged nanoparticles and the protonated CS polymers, the CS/nanoparticle complexes were utilized as templates for the subsequent polymerization of methacrylic acid. The resulting composite microspheres with luminescence and magnetic properties have regular morphologies and narrow size distributions. In contrast to previous reports, this route was based on a one-pot strategy without the aid of surfactants, organic solvent, or polymerizable ligands in aqueous solution. The encapsulated CdTe semiconductor nanocrystals inside the microspheres exhibited strong and stable photoluminescence properties in the pH range 5.0-11.0. When the pH was adjusted below 4, the photoluminescence decreased sharply and even quenched completely. However, the weakened fluorescence emission could be recovered to some degree upon an increase of pH above 5. Additionally, when both Fe(3)O(4) and CdTe nanoparticles were encapsulated within CS-PMAA microspheres, the magnetic content of the microspheres could be efficiently controlled by tuning the feeding molar ratio of MAA monomers and glucosamine units of CS. From the preliminary attempts, it was found that the multifunctional microspheres as imaging agents could improve the rate and extent of cellular uptake under short-term exposure to an applied magnetic field, and so exhibit a great potential as bioactive molecule carriers.
在本文中，我们提出了一种简便且稳健的方法来合成具有壳聚糖 - 聚（甲基丙烯酸）（CS - PMAA）壳层和碲化镉/氧化铁纳米颗粒核的多功能有机/无机复合微球。由于带负电荷的纳米颗粒与质子化的CS聚合物之间存在强静电相互作用，CS/纳米颗粒复合物被用作甲基丙烯酸后续聚合的模板。所得具有发光和磁性的复合微球具有规则的形态且尺寸分布狭窄。与先前的报道不同，该方法基于一锅法策略，在水溶液中无需表面活性剂、有机溶剂或可聚合配体的辅助。微球内部封装的CdTe半导体纳米晶体在pH值为5.0 - 11.0的范围内表现出强且稳定的光致发光特性。当pH值调节至低于4时，光致发光急剧下降甚至完全猝灭。然而，当pH值升高到5以上时，减弱的荧光发射可以在一定程度上恢复。此外，当Fe(3)O(4)和CdTe纳米颗粒都封装在CS - PMAA微球内时，通过调节MAA单体与CS的葡糖胺单元的进料摩尔比，可以有效地控制微球的磁性含量。从初步尝试中发现，作为成像剂的多功能微球在短期暴露于外加磁场的情况下可以提高细胞摄取的速率和程度，因此作为生物活性分子载体具有巨大潜力。
