Abstract The preparation of small, monodispersed magnetic microparticles through microfluidic approaches has been consistently challenging due to the high energy input needed for droplet break-off at such small diameters. In this work, we show the microfluidic production of 1–3 μm magnetic nanoparticle-loaded poly( d , l -lactide) (PLA) microspheres. We describe the use of two approaches, using a conventional flow-focusing microfluidic geometry. The first approach is the separation of target size satellite particles from the main droplets; the second approach is the direct production using high flow rate jetting regimes. The particles were produced using a polymeric thiol-ene microfluidic chip platform, which affords the straightforward production of multiple chip copies for single-time use, due to large feature sizes and replica molding approaches. Through the encapsulation of magnetite/maghemite nanoparticles, and their characterization with scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM) measurements, we show that the resulting particles are monosized, highly spherical and exhibit superparamagnetic properties. The particle size regime and their magnetic response show potential for in vivo intravenous applications of magnetic targeting with maximum magnetic response, but without blocking an organ’s capillaries.

中文翻译：

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用于生产低微米尺寸范围内的单分散超顺磁性微球的微流体方法

摘要 由于在如此小的直径下液滴破裂所需的高能量输入，通过微流体方法制备小的单分散磁性微粒一直具有挑战性。在这项工作中，我们展示了 1-3 μm 磁性纳米颗粒负载聚（d，l-丙交酯）（PLA）微球的微流体生产。我们描述了两种方法的使用，使用传统的流动聚焦微流体几何。第一种方法是从主要液滴中分离目标尺寸的卫星颗粒；第二种方法是使用高流速喷射方式直接生产。这些颗粒是使用聚合硫醇烯微流控芯片平台生产的，该平台可以直接生产多个芯片副本以供一次性使用，由于大的特征尺寸和复制成型方法。通过封装磁铁矿/磁赤铁矿纳米颗粒，并用扫描电子显微镜 (SEM) 和振动样品磁力计 (VSM) 测量对其进行表征，我们表明所得颗粒是单一尺寸、高度球形并具有超顺磁性。颗粒大小及其磁响应显示出具有最大磁响应但不阻塞器官的毛细血管的磁靶向的体内静脉内应用的潜力。