Micro/Nanorobots for Biomedicine: Delivery, Surgery, Sensing, and Detoxification

Abstract

Micro- and nanoscale robots that can effectively convert diverse energy sources into movement and force represent a rapidly emerging and fascinating robotics research area. Recent advances in the design, fabrication, and operation of micro/nanorobots have greatly enhanced their power, function, and versatility. The new capabilities of these tiny untethered machines indicate immense potential for a variety of biomedical applications. This article reviews recent progress and future perspectives of micro/nanorobots in biomedicine, with a special focus on their potential advantages and applications for directed drug delivery, precision surgery, medical diagnosis and detoxification. Future success of this technology, to be realized through close collaboration between robotics, medical and nanotechnology experts, should have a major impact on disease diagnosis, treatment, and prevention.

Fig. 1.. Actuation mechanisms and potential biomedical applications of various types of micro/nanorobots.

(A) Typical propulsion mechanisms of micro/nanoscale robots. (B) Chemically powered microrocket (30). Scale bar: 50 μm. (C) Magnetically actuated helical nanoswimmer (31). Scale bar: 200 nm. (D) Acoustically propelled nanowire motor (32). Scale bar: 200 nm. (E) Biologically propelled sperm hybrid microrobot (33). (F) Potential biomedical applications of nanorobots. (G) Magnetic helical microrobot for cargo delivery (38). Scale bar: 50 μm. (H) Micro-grippers for high precision surgery (39). Scale bar: 100 μm. (I) Antibody-immobilized microrobot for sensing and isolating cancer cells (40). Scale bar: 30 μm. (J) Red blood cell (RBC) membrane-coated nanomotor for biodetoxification (41).

Fig. 2.. Representative examples of micro/nanorobot-based in vivo delivery.

(A) Acid-powered zinc-based micromotors for enhanced retention in the mouse’s stomach (34). (B) Enteric micromotor, coated with a pH-sensitive polymer barrier (enteric coating) to bypass the acidic stomach environment, to selectively position and spontaneously propel in the gastrointestinal tract (35). (C) Controlled in vivo swimming of a swarm of bacteria-like microrobotic flagella (36). (D) Magneto-aerotactic motor-like bacteria delivering drug-containing nanoliposomes to tumor hypoxic regions (37).

Fig. 3.. Representative examples of micro/nanorobot-enabled precision surgery.

(A) Tetherless thermobiochemically-actuated microgrippers capturing live fibroblast cells (17). (B) Electroforming of implantable tubular magnetic microrobots for wireless eye surgery (64). (C) Acoustic droplet vaporization and propulsion of perfluorocarbon-loaded microbullets for tissue ablation (65). (D) Self-propelled nano-driller operating on a single cell (67). (E) Medibots: dual-action biogenic microdaggers for single-cell surgery (69).

Fig. 4.. Strategies and examples of micro/nanorobots for sensing.

(A) Functionalization of micro/nanorobot with different bioreceptors towards biosensing of target analytes, including cells, proteins, and nucleic acids. (B) ssDNA-functionalized microrockets for selective hybridization and isolation of nucleic acids (75). (C) Specific intracellular detection of miRNA in intact cancer cells using ultrasound-propelled nanomotors (80).

Fig. 5.. Representative examples of micro/nanorobots for detoxification.

(A) Transmission electron microscope image of a cell membrane-coated nanosponge used for toxin neutralization (81). (B) Scheme of the RBC-Mg Janus micromotor moving in biological fluid (left), and their capacity for cleanning of α-toxin (82). (C) Scanning electron microscope image of a 3D-printed microfish (top) and fluorescent image of the microfish incubated in melittin toxin solution after swimming (bottom part) (83).