Developing magnetic ultrasoft robots to navigate through extraordinarily narrow and confined spaces like capillaries in vivo requires synthesizing materials with excessive deformability, responsive actuation, and rapid adaptability, which are difficult to achieve with the current soft polymeric materials, such as elastomers and hydrogels. We report a magnetically actuatable and water-immiscible (MAWI) coacervate based on the assembled magnetic core–shell nanoparticles to function as a liquid robot. The degradable and biocompatible millimeter-sized MAWI coacervate liquid robot can remain stable under changing pH and salt concentrations, release loaded cargoes on demand, squeeze through an artificial capillary network within seconds, and realize intravascular targeting in vivo guided by an external magnetic field. We believe the proposed “coacervate-based liquid robot” can implement demanding tasks beyond the capability of conventional elastomer or hydrogel-based soft robots in the field of biomedicine and represents a distinct design strategy for high-performance ultrasoft robots.

中文翻译：

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水不混溶凝聚层作为用于血管内导航的液磁机器人

开发磁性超软机器人以在体内毛细血管等极其狭窄和受限的空间中导航需要合成具有过度变形性、响应性驱动和快速适应性的材料，这是目前的软聚合物材料（如弹性体和水凝胶）难以实现的。我们报告了一种基于组装的磁性核壳纳米颗粒的可磁致动和水不混溶 (MAWI) 凝聚层，可用作液体机器人。可降解且具有生物相容性的毫米级 MAWI 凝聚层液体机器人可以在 pH 值和盐浓度变化的情况下保持稳定，按需释放装载的货物，在几秒钟内挤压通过人工毛细血管网络，并在外部磁场的引导下实现体内血管内靶向。