Wang Huixia, Pu Ximing, Zhou Yaquan, Chen Xianchun, Liao Xiaoming, Huang Zhongbing, Yin Guangfu
College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
Materials (Basel). 2018 Aug 23;11(9):1508. doi: 10.3390/ma11091508.
Macroporous magnetic Fe₃O₄ microparticles, which might act as both drug carriers and magnetocaloric media, were expected to have broad application prospects on magnetocaloric-responsively controlled drug release systems. A kind of macroporous magnetic Fe₃O₄ microparticle was prepared by an organic matter assisted open-cell hollow sphere (hollow sphere with holes on shell) assembly method in this study. 1-vinyl-2-pyrrolidinone (NVP) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) were selected as the template and the binder, respectively. Ferrous ions were specifically bound to carbonyl groups on NVP and were then reduced by NaBH₄. The reduced irons underwent heterogeneous nucleation and grain growth to form Fe⁰/Fe₃O₄ microspheres consisting of a lot of nano-Fe⁰ grains, and were then assembled into Fe⁰/Fe₃O₄ microparticles wrapped by AMPS. Results indicate that NVP binding with ferrous ions can promote a self-polymerization process and the formation of Fe⁰/Fe₃O₄ microspheres, while AMPS enwrapping around the resultant microspheres can facilitate their assembly into larger aggregates. As a result, macroporous Fe₃O₄ microparticles composed of several open-cell hollow Fe₃O₄ microspheres can be obtained under a Kirkendall-controlled oxidation. Moreover, these as-prepared macroporous Fe₃O₄ microparticles possess a narrow particle size distribution and exhibit ferromagnetism (Ms = 66.14 emu/g, Mr = 6.33 emu/g, and Hc = 105.32 Oe). Our work, described here, would open up a novel synthesis method to assemble macroporous magnetic Fe₃O₄ microparticles for potential application in magnetocaloric-responsively controlled drug release systems.
大孔磁性Fe₃O₄微粒有望在磁热响应控制药物释放系统中具有广阔的应用前景，它既可以作为药物载体，又可以作为磁热介质。本研究采用有机物辅助开孔空心球（壳上有孔的空心球）组装法制备了一种大孔磁性Fe₃O₄微粒。分别选用1-乙烯基-2-吡咯烷酮（NVP）和2-丙烯酰胺基-2-甲基丙磺酸（AMPS）作为模板和粘结剂。亚铁离子特异性结合到NVP上的羰基上，然后被NaBH₄还原。还原后的铁发生异质形核和晶粒生长，形成由许多纳米Fe⁰晶粒组成的Fe⁰/Fe₃O₄微球，然后组装成被AMPS包裹的Fe⁰/Fe₃O₄微粒。结果表明，NVP与亚铁离子的结合可以促进自聚合过程和Fe⁰/Fe₃O₄微球的形成，而AMPS包裹在所得微球周围可以促进它们组装成更大的聚集体。因此，在柯肯达尔控制氧化条件下，可以得到由几个开孔空心Fe₃O₄微球组成的大孔Fe₃O₄微粒。此外，这些制备的大孔Fe₃O₄微粒具有窄的粒径分布，并表现出铁磁性（Ms = 66.14 emu/g，Mr = 6.33 emu/g，Hc = 105.32 Oe）。我们在此描述的工作将开辟一种新颖的合成方法来组装大孔磁性Fe₃O₄微粒，用于磁热响应控制药物释放系统的潜在应用。
