On May 20, 2020, the micro-nano intelligent system team of Shanghai Research Institute for Intelligent Autonomous Systems, developed a biomimetic magnetic microrobot (BMM) inspired by magnetotactic bacteria (MTB) with speedy motion response and accurate positioning for targeted thrombolysis.It was published online inAdvanced Materials(https://doi.org/10.1002/adma.202000366).

Cardiovascular diseases seriously threaten human health with the high mortality rate. The thrombus in large blood vessels can be treated by catheterization, but those in small blood vessels can hardly be treated in the same way. Microrobots are expected to provide a new platform for the microvascular thrombosis. In the low Reynolds number environment of human body, a continuous external driving force is necessary to control the microrobot. Therefore, it is challengingto realize the efficient driving and motion control of micro-scale robots in the low Reynolds number environment.In addition, a single microrobot cannot satisfy the requirements of medical applications.It is necessary to control aswarm of microrobotsin collective manner according to the demand of biomedical doses.Developingsoft medical microrobots with biocompatibility, effective driving and accurate control is demanded.

Magnetotactic bacteria (MTB), a class of prokaryotic organism, are natural microrobots which can be controlled via the magneticfield. Magnetosomes, a membrane bound prokaryotic organelle with aligned iron-rich nanocrystals in MTB, enable the bacteria to flexibly coordinate their movement under the magnetic field in a collective manner.Inspired by nature, the joint team developed anew type ofmicrorobot, namely BMM, which mimic the ordered internal structure of magnetosomes inMTB. BMMs showedprominent biocompatibility in terms of the composition, contact interface and control mode.The experiment and numerical simulation confirmed that the internal driving structure, magnetic field strength and frequency affect the locomotion properties. And the maximum velocity was up to 161.7µm/s.Moreover, the microrobots can simultaneously respond to multiple instructions, generating heat and forces to realize multi-functions. Via the combination of physical stimuliand locally released thrombolytic drugs, BMMs become a strong scavenger for the microvascular thrombus.

The project wassupported by Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University and Shanghai East Hospital. It was fundedby the National Natural Science Foundation of China, Shanghai Municipal Education Commission Innovative Program, the Shanghai Zhangjiang National Independent Innovation Demonstration Area Special Development Fund Major Project.