Alkaline-Driven Liquid Metal Janus Micromotor with a Coating Material-Dependent Propulsion Mechanism

Abstract

Micro/nanomotors have achieved huge progress in driving power divergence and accurate maneuver manipulations in the last two decades. However, there are still several obstacles to the potential biomedical applications, with respect to their biotoxicity and biocompatibility. Gallium- and indium-based liquid metal (LM) alloys are outstanding candidates for solving these issues due to their good biocompatibility and low biotoxicity. Hereby, we fabricate LM Janus micromotors (LMJMs) through ultrasonically dispersing GaInSn LM into microparticles and sputtering different materials as demanded to tune their moving performance. These LMJMs can move in alkaline solution due to the reaction between Ga and NaOH. There are two driving mechanisms when sputtering materials are metallic or nonmetallic. One is self-electrophoresis when sputtering materials are metallic, and the other one is self-diffusiophoresis when sputtering materials are nonmetallic. Our LMJMs can flip between those two modes by varying the deposited materials. The self-electrophoresis-driven LMJMs’ moving speed is much faster than the self-diffusiophoresis-driven LMJMs’ speed. The reason is that the former occurs galvanic corrosion reaction, while the latter is correlated to chemical corrosion reaction. The switching of the driving mechanism of the LMJMs can be used to fit into different biochemical application scenarios.

Asymmetric colloidal motors: from dissymmetric nanoarchitectural fabrication to efficient propulsion strategy

“…5D). 101 The JCMs moves in the direction of monomer concentration gradient, and this result lays the foundation for special targeted movement in the future.…”

Emerging Liquid Metal Biomaterials: From Design to Application

“…[21] LM micro-/nanomotors with well-designed surface chemical reactions with the surrounding environment and architectures for effective propulsion in biological fluids and performance of the desired functions in specific locations have also been explored for targeted therapy. [24,[64][65][66][67][68] For instance, enzymes with high biocompatibility have been explored for targeting drug delivery to improve therapeutic effects. Enzyme-powered targeted transportation of LM was developed by modifying enzymes on the LM surface.…”

“…Moreover, LMs applied for target treatment can also be achieved by converting chemical energy into mechanical forces through heterogeneous microstructure construction. [65,66,68] A Janus microstructure motor designed by asymmetrically coating Ga on zinc (Zn) microparticles showed self-propulsion behavior in simulated gastroenteric acid. This motion of Ga/Zn micromotors propelled by hydrogen bubbles generated by the zinc-acid reaction was improved by Ga-Zn galvanic effects, which can be applied for targeting antimicrobial chemotherapy (Figure 5e).…”

Nanoswimmers Based on Capped Janus Nanospheres

“…Lastly, the novel liquid metal (LM) alloys such as GaInSn are also worth highlighting, as they have seen creative use in nanoswimmer applications in recent years, in part due to their biocompatible nature. For example, the use of Ga in the core element in swimmers, instead of more traditional polymer or silica particles, has enabled their use in applications such as microwelding [65], treatment of bacterial infections [66] and swimming in alkaline environments [67]. The Ga endows the particles with bactericidal properties [66] and propulsion through self-electrophoresis or self-diffusiophoresis in NaOH containing environments depending on the coating material of the spheres (either metallic or non-metallic, respectively) [67].…”