Micro‐/Nanorobots at Work in Active Drug Delivery

Abstract

After the tremendous advances over the past two decades, micro‐/nanorobots can effectively convert other forms of energy into propulsion and movement, as well as be navigated to targeted locations under physiological conditions and environments. They have been demonstrated to have the potential to load, transport, and deliver therapeutic payloads directly to disease sites, thereby improving the therapeutic efficacy and reducing systemic side effects of highly toxic drugs. In this feature article, the various propulsion modalities of micro‐/nanorobots ranging from chemical/biochemical reactions to external fields, and to motile microorganisms are summarized and commented in terms of driving forces required by the automotive motion in biological media, biocompatibility, as well as the corresponding advantages and limitations in terms of biomedical applications. Then, the latest developments of in vitro and in vivo active drug delivery based on micro‐/nanorobots are discussed in detail. The challenges and future prospects are also highlighted in the end. With ever booming research enthusiasm in this field and increasing multidisciplinary cooperation, micro‐/nanorobots with intelligence and multifunctions will emerge in the near future, which would have a profound impact on the treatment of diseases.

Magnetic tri-bead microrobot assisted near-infrared triggered combined photothermal and chemotherapy of cancer cells

“…6 A (see Video S2); in other words, the change in posture is an indication that the microrobots came into contact with the cells. This phenohemon was observed in previous studies where the environmental conditions affected the motion of the microrobots 24 . The average velocity of the tri-bead/azo/DOX microrobots in this experiment was 14.5 µm/s.…”

Magnetic Miniature Soft Robot with Reprogrammable Drug‐Dispensing Functionalities: Toward Advanced Targeted Combination Therapy

“…This demonstration shows that our soft robot can indeed dispense four drugs, and this is a significant advancement over all the existing miniature robots since they can only carry at most three types of drugs. [ 7–15,20–40 ] Furthermore, by having the ability to dispense its drugs selectively, our soft robot also shows a major improvement over those existing miniature robots that are unable to do so. [ 33 ] Unlike miniature robots that must release all their drugs simultaneously at one site, [ 33 ] our soft robot is also much more robust since it has no such constraints.…”

“…This demonstration therefore indicates that our robot can realize unprecedented reprogrammable drug‐dispensing abilities since existing small‐scale untethered actuators are unable to transport more than three types of drugs, and change their dispensing sequence and dosage. [ 7–15,20–40 ] By enabling such reprogrammable abilities, miniature robots will now have great potential toward performing advanced targeted combination therapies via the active delivery method.…”

Orientation-dependent propulsion of cone-shaped nano- and microparticles by a traveling ultrasound wave

“…In summary, this work solves problems and provides new insights that are highly important on the way towards the intriguing applications that have been envisaged for ultrasound-propelled nano-and microparticles [7][8][9][10][11][12][13][14][15][16]. In the future, this work should be continued by varying the particle shape, particle size, ultrasound frequency, ultrasound intensity, and other parameters of the system and studying how this affects, e.g., the orientation-averaged propulsion velocity or the fixed points of the particle orientation.…”