Microfluidic Shape-Memory Microparticles for Embolization System

Embolization that involves the selective occlusion of blood vessels may be used to control or prevent abnormal bleeding, close off vessels supplying blood to a tumor, eliminate abnormal connections between arteries and veins, or to treat aneurysms. It is a highly effective way to control bleeding and is much less invasive than open surgery. The selection of an embolic agent is based on many considerations, notably on the clinical indication for the procedure, on the desire to produce temporary or permanent occlusion, on the level of occlusion, on flow dynamics/collateral circulation, on the risk of complications such as necrosis or nontarget embolization, and on cost. Microparticles embolics can be made of several types of materials such as hydrogels able to swell after injection until occlusion.^1,2<br/>Shape-memory polymers (SMPs) are remarkable stimuli-responsive materials able to switch from one stable macroscopic shape to another one, are also of prime interest to afford well-controlled embolization systems. Among shape-memory materials, poly(ε-caprolactone) (PCL) networks are widely studied for biomedical applications since PCL is biocompatible, and biodegradable.<br/>In our work we formulated by a microfluidic system, shape-memory microparticles composed of 4-arms PCL stars end-functionalized by coumarins³. The obtained highly monodispersed particles were crosslinked by on-line UV irradiation (365nm). These crosslinked particles that still exhibit crystallinity possess temperature triggered shape-memory properties by heating above the melting temperature, around 50°C, making them promising hydrophobic and biodegradable candidates for embolization aplication.<br/>1 B. Liu, Z. Xu, H. Gao, C. Fan, G. Ma, D. Zhang, M. Xiao, B. Zhang, Y. Yang, C. Cui, T. Wu, X. Feng and W. Liu, <i>Adv. Funct. Mater.</i>, 2020, <b>1910197</b>, 1–12.<br/>2 Y. Chen, J. Zhang, Y. Zou and Y. Wu, <i>Front. Chem.</i>, 2019, <b>7</b>, 1–11.<br/>3 T. Defize, J. Thomassin, H. Ottevaere, G. Eppe, C. Jérôme and R. Riva, <i>Macromolecules</i>, 2019, 444–456.