自供电纳米复合材料在外旋转磁场下用于非侵入性的电刺激

外源性电刺激在临床和实验研究中得到了广泛的应用，如刺激轴突生长，调节分化和大脑皮层，修复受损皮肤，建立大鼠断肢残端组织的再生模型，促进心肌细胞成熟。然而，由于电刺激过程中使用生物电极，芯片、细胞膜以及作为内外导电介质的导电聚合物，连接外部电源是非常不方便的。因此，制备一种简单的电子传输无线电源供应系统仍然是一个挑战。

最近，西南交通大学的郑晓彤教授和杨维清教授团队研发了一种m-MWNT包覆Fe₃O₄ / PCL自供电的复合纳米纤维。由于电磁感应效应，自供电纳米复合材料可在外加磁场作用下产生电流，切割磁通量的电流密度可达191.1 A/m²。当设计的磁场停止旋转时，CNFs可以自由地控制自供电运动的开/关。其制备过程如下，首先通过静电纺丝将 Fe₃O₄/PCL/DCE/DMF混合溶液制备Fe3O4/PCL纤维毡，接着，分散在混合溶液中（乙醇和二氯甲烷）的碳纳米管通过真空辅助喷雾技术将包覆在纤维的表面制备复合纳米纤维。PCL由于其良好化学稳定性、机械稳定性，生物相容性而作为纤维的基体材料。此外，复合纳米纤维能替代牛蛙坐骨神经实现功能性电刺激。碳纳米纤维具有较低的细胞毒性和优异的生物相容性，植入体内无炎症反应。

Exogenous electrical stimulation has been effectively used in both clinical practice and laboratory research to stimulate neurite outgrowth, regulate differentiation and cerebral cortex, heal injured skin, establish a regeneration model of specific tissues in the stump of a rat limb amputation and promote cardiomyocyte maturation. However, the connecting requirement of an external power source to enable the electrical stimulation process is inconvenient in biomedical applications because of the use of bioelectrodes, chips, cell-membranes and a conductive polymer platform as the internal−external conducting medium. Developing a wireless power source supply with simple electronic transport remains a challenge, especially for electrical stimulation.

Recently, Xiaotong Zheng and Weiqing Yang who working in the School of Southwest Jiaotong University made the following outcome. In this work, they demonstrated a facile method to fabricated a noninvasive external power supply using a self-powered selfpowered composite nanofiber (CNF) composed of m-MWNTs coated Fe3O4/PCL nanofibers under an external alternating magnetic field. On the basis of the electromagnetic induction effect, this self-powered nanocomposite can generate power when an external magnetic field is applied to the CNF. At the same time, the CNF can freely control the on/off self-powered motion when the designed magnetic field stops rotating. Here, the fabrication method consists of (i) the dispersion of m-MWNTs in a mixed solution (ethanol and DCE), (ii) the preparation of Fe₃O₄ /PCL/DCE/DMF solution, and (iii) the incorporation of the m-MWNTs by spraying the solution from (i). Furthermore, the method of generating current from the CNF using an external magnetic field in low-power consumption and unique environments can achieve when the CNFs replaced a bullfrog’s sciatic nerve. The CNFs possessed excellent cytotoxicity and good enough biocompatibility to be implanted in vivo without causing any inflammation.

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