Biodegradable Janus Particles with Zwitterionic Nature for Arterial Embolization

In arterial embolization, embolic particles should be deformable for smoother injection and large enough for effective occlusion of arteries. So far, a common compromise between the apparently conflicting requirements is the use of a spherical particle of narrow size distribution, which still requires delicate operation technique. Herein, we present a novel strategy to meet the two requirements together: small deformable Janus particles with zwitterionic nature smoothly transport through catheters and slowly form large aggregates with effective vascular occluding properties. Biodegradable Janus particles composed of positive and negative charged compartments were prepared by a surfactant-free micromolding technique, and the two compartments provided a pH dependent ionic interaction of relatively short-range compared to the particle size. The short-range attraction enabled convenient delivery through a micro-catheter and effective particle assembly upon accumulation at the target site, which was confirmed in the in vivo study of a rabbit renal embolization model. Successful in vivo CT tracing was provided by homogeneously dispersed gold nanoparticles permanently anchored to the chitosan hydrogel. The unique assembly behavior of Janus particles could break the current limits of embolization technology.