TABLE 2.

External-field-powered MNRs for motile-targeting drug delivery.

Energy sources		Representative examples	Environment	Motion behavior	Loaded cargo/therapeutic drugs	Biomedical application	Ref.
Light	NIR	Pt NPs modified polymer multilayer micromotors	In vitro	Maximum speed ≈62 μm/s	N.A.	Photothermal therapy	Wu et al. (2014)
		MPCM@JMSNMs	In vitro	0.9 μm/s ∼ 5.98 μm/s	Propidium iodide	Drug delivery for cancer	Xuan et al. (2018)
		Membrane-cloaked Janus polymeric motors	In vitro	2.33 μm/s ∼ 19.8 μm/s	Heparin	Drug delivery and Photothermal therapy for thrombus	Shao et al. (2018)
		Photothermally-driven polymersome nanomotors	In vitro	≈1.9 μm/s ∼ 6.2 μm/s	Propidium iodide	Intracellular Drug delivery	Shao et al. (2020)
		Platelet-derived porous nanomotors	In vitro	Maximum speed ≈4.5 μm/s	Urokinase	Thrombus therapy	Wan et al. (2020)
			In vivo		Heparin
		Janus calcium carbonate particle micromotors	In vitro	2.9 μm/s ∼ 7.3 μm/s	DOX	Drug delivery	Zhou et al. (2021)
	X-ray	Half-copper-coated silica (Cu/SiO2) Janus microparticles	In vitro	Maximum speed ≈1.2 μm/s	N.A.	Potential for enhancing diagnosis and radiotherapy	Xu Z et al. (2019)
	UV	Photoelectrochemical TiO2-Au-nanowire-based motors	In vitro	Speed of 5.6 ± 1.5 μm/s	N.A.	Ocular disease (neural RGC stimulation)	Chen et al. (2021)
Ultrasound		Asparaginase-modified nanowire motors	In vitro	5 μm/s ∼ 60 μm/s	Asparaginase	Cancer cells inhibition	Uygun et al. (2017)
		Cas9-sgRNA@AuNW motors	In vitro	≈22 μm/s	Cas9-sgRNA Complex	Drug delivery (e.g., gene therapy)	Hansen-Bruhn et al. (2018)
		Liquid metal nanomachines	In vitro	4.6 μm, 420 kHz, 47.4 μm/s	N.A.	Photothermal therapy for cancer	Wang et al. (2018)
		AuNS functionalized polymer multilayer tubular nanoswimmers	In vitro	5 μm/s ∼ 80 μm/s	N.A.	Potential for various biomedical applications (e.g., gene delivery)	Wang Q et al. (2019)
		RBCM-micromotors	In vitro	Maximum speed ≈56.5 μm/s	Oxygen and ICG	Photodynamic cancer therapy	Gao et al. (2019)
Magnetic field		Multifunctional nanorobot systems (MF-NRS)	In vitro	4.5 ± 2.2–10.37 ± 5.3 mm/s	DOX	Chemo-phototherapy for cancer	Jin et al. (2019)
			In vivo
		HADMSC-based medical microrobots	In vitro	N.A.	Mesenchymal stem cell	Cartilage repair	Go et al. (2020)
			In vivo
		Bilayer hydrogel sheet-type intraocular microrobots	In vitro	N.A.	DOX	Ocular disease (e.g., retinoblastoma)	Kim et al. (2020)
		Leukocyte-inspired mult-ifunctional microrollers	In vitro	600 μm/s	DOX	Various diseases (e.g., cancer)	Alapan et al. (2020)
		Photosynthetic bohybrid nanoswimmers	In vitro	Maximum speed ≈78.3 μm/s	Chlorophyll	Cancer treatment	Zhong et al. (2020)
			In vivo
		Sequential magneto-actuated and optics-triggered biomicrorobots	In vitro	Average speed: 13.3 ± 4.5 μm/s	ICG nanoparticles	Various disease (e.g., cancer)	Xing et al. (2021)
			In vivo
		ICG/R837 loading and DPA-PEG coating magnetic nanoparticles	In vivo	N.A.	ICG and immune-ostimulator R837 hydrochloride	Photothermal/immunotherapy for cancer	Zhang et al. (2020)
		Magnetic tri-bead microrobots	In vitro	Average velocity: 14.5 μm/s	DOX	Photothermal therapy and chemotherapy	Song et al. (2021)
		Magnetic-actuated “capillary container”	In vitro	N.A.	N.A.	Selective fluid colle-ction, drug delivery	Zhang Y et al. (2021)
		Personalized magnetic micromachines	In vitro	Maximum speed: 9.3–9.8 μm/s	Cell tracker deep red dye	Potential for drug delivery	Ceylan et al. (2021)
		Au-Ni nanowires	In vitro	6.35–21.5 μm/s	DOX and ssDNA	Drug delivery	Karaca et al. (2021)
		Nickel-based spherical Janus magnetic microrobots	In vitro	0.97 ± 0.27 mm/s	N.A.	Potential for drug delivery	Wrede et al. (2022)