Research On Fabrication And Motion Control Of Acoustic Propelled Liquid Metal Nanomotors

Artificial micro/nanomotor and its applications have been an appealing research hotpoint in resent years.In this work we integrate artificial micro/nanomotor and Gallium-based liquid metals to produce liquid metal nanomotor,and drive motors’ locomotion by using acoustic field as power source,the movement behavior and mechansim of liquid metal nanomotors are analyzed.Gallium-based liquid metals own the characters of low melting point,high boiling point,no vapor pressure and high biocompatibility.In this project,ultrasoundassisted physical dispersion methods are used to prepare liquid metal nanospheres with different particle diameters.The average particle size distribution is in the range of 200 nm to 40 nm,depending on the conditions used.In addition to the nanospheres,EGa In alloy nanorods are prepared by long-time ultrasonic crushing.The nanorods have an average diameter of 100 nm and an average length of 780 nm.The nanorods contain a GaOOH shell and the liquid metal core.The time and power of ultrasonic breakage are both related to the average particle size,while the ratio of ultrasonic breaking time and water ratio in the mixed solvent of alcohol water system is positively related to the formation of nanorods by influence the oxidation capacity of the synthetic system.The motion of liquid metal nanomotor driven with MHz level ultrasonic wave is used.Compared with symmetrical gallium nanospheres and Si O2 microspheres,EGa In nanorods with asymmetrical shape have good response to ultrasonic field.The velocity of EGa In nanorods’ motion in ultrasonic field can reach 50 body length per second,exceeding most of natural swimmers in low Reynolds number environment,such as bactera.At the same time,the group aggregation behavior of the EGa In nanomotors under ultrasonic driving is observed.By opening and closing the ultrasonic field,the group can be formed and dispersed,and the aggregation position of the aggregates can be adjusted by adjusting the frequency of the ultrasonic field,that is,the movement direction of the aggregate can be adjusted.The biological application of liquid metal nanomometers is briefly explored in two aspects: photoluminescence(PL)effect of liquid metal and the biomembrane camouflage.The PL effect of EGa In nanomotors is used to mark and observe the cancer cells.The phospholipid membrane camouflaged liquid metal nanomotor with doxorubicin is prepared.The phospholipid membrane camouflage has no obvious negative effect on the motion performance of nanomotor.The speed of nano motor can still reach 37 μm/s after coating the phospholipid membrane.It indicates that the ultrasonic driven liquid metal nanomaterials have promising biological application prospects.In summary,this paper proposes the preparation of liquid metal nanomotors using high-energy ultrasonic processing methods,and realizes that by changing the frequency,amplitude and other variables of the applied low-energy ultrasonic fields,changing the aggregates’ moving speed,aggregation morphology,etc.,and verifying the application prospects of liquid metal nanomotors in labeling cells and drug delivery.