Polymersomes from Dual Responsive Block Copolymers: Drug Encapsulation by Heating and Acid-Triggered Release

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• 作者：Zeng-Ying Qiao ; Ran Ji ; Xiao-Nan Huang ; Fu-Sheng Du ; Rui Zhang ; De-Hai Liang ; Zi-Chen Li
• 刊名：Biomacromolecules
• 出版年：2013
• 出版时间：May 13, 2013
• 年：2013
• 卷：14
• 期：5
• 页码：1555-1563
• 全文大小：468K
• 年卷期：v.14,no.5(May 13, 2013)
• ISSN：1526-4602

文摘

A series of well-defined thermoresponsive diblock copolymers (PEO₄₅-b-PtNEA_n, n = 22, 44, 63, 91, 172) were prepared by the atom transfer radical polymerization of trans-N-(2-ethoxy-1,3-dioxan-5-yl) acrylamide (tNEA) using a poly(ethylene oxide) (PEO₄₅) macroinitiator. All copolymers are water-soluble at low temperature, but upon quickly heating to 37 掳C, laser light scattering (LLS) and transmission electron microscopy (TEM) characterizations indicate that these copolymers self-assemble into aggregates with different morphologies depending on the chain length of PtNEA and the polymer concentration; the morphologies gradually evolved from spherical solid nanoparticles to a polymersome as the degree of polymerization (鈥?i>n鈥? of PtNEA block increased from 22 to 172, with the formation of clusters with rod-like structure at the intermediate PtNEA length. Both the spherical nanoparticle and the polymersome are stable at physiological pH but susceptible to the mildly acidic medium. Acid-triggered hydrolysis behaviors of the aggregates were investigated by LLS, Nile red fluorescence, TEM, and ¹H NMR spectroscopy. The results revealed that the spherical nanoparticles formed from PEO₄₅-b-PtNEA₄₄ dissociated faster than the polymersomes of PEO₄₅-b-PtNEA₁₇₂, and both aggregates showed an enhanced hydrolysis under acidic conditions. Both the spherical nanoparticle and polymersome are able to efficiently load the hydrophobic doxorubicin (DOX), and water-soluble fluorescein isothiocyanate-lysozyme (FITC-Lys) can be conveniently encapsulated into the polymersome without using any organic solvent. Moreover, FITC-Lys and DOX could be coloaded in the polymersome. The drugs loaded either in the polymersome or in the spherical nanoparticle could be released by acid triggering. Finally, the DOX-loaded assemblies display concentration-dependent cytotoxicity to HepG2 cells, while the copolymers themselves are nontoxic.