Compartmentalized Microgels with Programmed Acoustic Anisotropy for Orthogonal Ultrasound-Triggered Motion and Cargo Release
Abstract
Compartmentalization is a fundamental organizational principle in nature, enabling anisotropy required for controlled locomotion and spatiotemporal regulation of biological processes. Inspired by this principle, we present a one-step strategy to fabricate compartmentalized anisotropic microgels via liquid–liquid phase separation (LLPS) in aqueous droplets. Upon sodium chloride addition, concentrated N-isopropylacrylamide (NIPAAm) solutions spontaneously separate into NIPAAm-rich and NIPAAm-poor phases. Integrating this process into microfluidic droplets followed by photopolymerization enables continuous fabrication of anisotropic PNIPAAm microgels with two compartments of distinct stiffness. Synthetic and biological macromolecules can be selectively loaded into different compartments according to their polarity. Crucially, LLPS-generated acoustic contrast enables two independently addressable functionalities under biocompatible ultrasound (US). Lowfrequency, low-intensity US induces propulsion at speeds of approximately 10 microgel diameters per second without cargo release, whereas high-frequency, higher-intensity US at biocompatible settings selectively degrades one compartment, enabling on-demand cargo release. Complementary computer simulations further elucidate the physical mechanisms underlying acoustically driven motion. This work establishes LLPS-driven compartmentalization as a design principle for multifunctional colloidal microrobots with independently programmable propulsion and cargo release, opening new avenues for targeted drug delivery and soft robotics.
Authors 6
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Affiliation as printed
Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 2 , 52074 Aachen , Germany
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Affiliation as printed
Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 2 , 52074 Aachen , Germany
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Affiliation as printed
Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 2 , 52074 Aachen , Germany
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Affiliation as printed
Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 2 , 52074 Aachen , Germany
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Affiliation as printed
Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 2 , 52074 Aachen , Germany
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Affiliation as printed
Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 2 , 52074 Aachen , Germany