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arXiv 1703.09586cond-mat.soft
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磁性脂质体的可逆和不可逆聚集

Reversible and Irreversible Aggregation of Magnetic Liposomes

Sonia Garcia-Jimeno, Joan Estelrich, Jose Callejas-Fernandez, Sandalo Roldan-Vargas

摘要:

了解磁性纳米颗粒系统的稳定和聚集对于优化这些系统在实际生理应用中的功能至关重要。在这里,我们解决这个问题的一个具体的,但代表性的系统。我们提出了一个实验和分析研究超顺磁性脂质体在悬浮液中的聚集在可控的外部磁场的存在下。我们研究了聚集动力学,并报告了中间时间的平均聚集扩散系数的幂律演化和长时间的稳定值,两者都取决于磁场强度。然后,我们表明,长时间的聚集体结构是分形的分形维数,增加磁场强度。通过标度参数,我们还建立了聚集体分形维数和控制聚集动力学的幂律指数之间的解析关系。这种关系实际上与磁场强度无关。尽管我们的粒子具有超顺磁性,但我们进一步证明了在关闭外部磁场后仍能保持其完整性的幸存聚集体群体的存在。最后,我们提出了一个示意性的相互作用的情况下,合理化观察到的可逆和不可逆的聚集之间的共存。

英文摘要:

Understanding stabilization and aggregation in magnetic nanoparticle systems is crucial to optimizing the functionality of these systems in real physiological applications. Here we address this problem for a specific, yet representative, system. We present an experimental and analytical study on the aggregation of superparamagnetic liposomes in suspension in the presence of a controllable external magnetic field. We study the aggregation kinetics and report an intermediate time power law evolution and a long time stationary value for the average aggregate diffusion coefficient, both depending on the magnetic field intensity. We then show that the long time aggregate structure is fractal with a fractal dimension that decreases upon increasing the magnetic field intensity. By scaling arguments we also establish an analytical relation between the aggregate fractal dimension and the power law exponent controlling the aggregation kinetics. This relation is indeed independent on the magnetic field intensity. Despite the superparamagnetic character of our particles, we further prove the existence of a population of surviving aggregates able to maintain their integrity after switching off the external magnetic field. Finally, we suggest a schematic interaction scenario to rationalize the observed coexistence between reversible and irreversible aggregation.

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