Acoustically-Propelled Rodlike Liquid Metal Colloidal Motors

We report an acoustically-propelled rodlike liquid metal eutectic gallium-indium alloy (EGaIn) colloidal motor capable of actively seeking and internalizing into cancer cells. These rod-shaped EGaIn colloidal motors with a length of 1 μm and a diameter of 200 nm are prepared by a simple sonication crushing method, which is demonstrated to be a core-shell structure with a 30 nm GaOOH shell and zero-valent liquid core. A wide spectrum range of light absorbance is demonstrated by using UV-vis-NIR spectroscopy and confocal laser scanning microscopy with excitation wavelengths of 488 nm, 543 nm, and 633 nm. Upon exposure to the acoustic field, the rodlike EGaIn colloidal motors can autonomously move at a speed of up to 34.5 μm s⁻¹ without addition of any chemical fuels. The speed of motion is also able to be modulated by adjusting the acoustic voltage. Furthermore, these rodlike EGaIn colloidal motors could actively target and internalize into cancer cells which could be real-time monitored due to their photoluminance feature. Such rodlike liquid metal colloidal motors have promising applications in biomedical fields.