Dual-Energy Integration in Photoresponsive Micro/Nanomotors: From Strategic Design to Biomedical Applications

Abstract

Micro/nanomotors (MNMs) are highly versatile small-scale devices capable of converting external energy inputs into active motion. Among the various energy sources, light stands out due to its abundance and ability to provide spatiotemporal control. However, the effectiveness of light-driven motion in complex environments, such as biological tissues or turbid water, is often limited by light scattering and reduced penetration. To overcome these challenges, recent innovations have integrated light-based actuation with other external stimuli-such as magnetic, acoustic, and electrical fields-broadening the functional range and control of MNMs. This review highlights the cutting-edge developments in dual-energy powered MNMs, emphasizing examples where light is paired with secondary energy sources for enhanced propulsion and task performance. Furthermore, insights are offered into the fabrication techniques, biomedical applications, and the future directions of such hybrid MNMs, while addressing the remaining challenges in this rapidly evolving field.

Keywords: biomedical applications; dual‐energy sources; multifunctional systems; photocatalytic micro/nanomotors.

Figure 1

Schematic illustration showing the most representative examples of dual‐responsive LMNMs and the corresponding advantages they offer, including enhanced propulsion efficiency, improved control, adaptability in complex environments, and increased functionality in biomedical or environmental applications.

Figure 2

Wet‐chemical fabrication methods of dual‐engine LMNMs. A) Hydrothermal reaction. B) Sol–gel synthesis. C) MACE. Scanning electron microscopy (SEM)/Transmission electron microscopy (TEM) images were adapted with permission. (A)^{[ 7 ]} Copyright 2023, John Wiley and Sons, (B)^{[ 56 ]} Copyright 2022, American Chemical Society, (C)^{[ 57 ]} Copyright 2023, The American Association for the Advancement of Science.

Figure 3

Main deposition techniques used for fabricating LMNMs. A) Physical Vapor Depositions: i) sputtering; ii) thermal evaporation; and iii) electron‐beam evaporation. B) Atomic Layer Deposition. C) Electrochemical deposition. D) Layer by Layer Deposition. SEM/TEM images were adapted with permission. (A)^{[ 83 ]} Copyright 2021, Springer Nature, (B)^{[ 84 ]} Copyright 2017, Royal Society of Chemistry, (C)^{[ 85 ]} Copyright 2022, American Chemical Society, (D)^{[ 86 ]} Copyright 2018, American Chemical Society.

Figure 4

Representative illustration of electromagnetic spectrum and commonly used photoresponsive materials.

Figure 5

Representative illustration of optical/chemical‐powered MNMs and the typical motion modes. The inset indicates: an increase in chemical fuel concentrations accelerates the movement of LMNM; an increase in light intensity can lead to the acceleration, break, or reversal behavior of LMNM.

Figure 6

Representative illustration of optical/magnetic‐powered MNMs and the typical motion modes. Insets: the upper panel presents the commonly used setups; the lower panel describes the functionalities that a magnetic field may provide, such as directionality and acceleration.

Figure 7

Representative illustration of optical/acoustic‐powered MNMs and the typical motion modes. Insets: the upper panel presents the commonly used setups; the lower panel describes the functionalities that an acoustic field may offer, such as acceleration, brake, reverse, and collective behaviors.

Figure 8

Representative illustration of optical/electric‐powered MNMs and the typical motion modes. Insets: the upper panel presents the commonly used setups; the lower panel describes the functionalities that an electric field may offer, such as rotation and acceleration.

Figure 9

Schematic illustration of dual‐energy source‐powered MNMs in biomedical application. A) Photothermal therapy (PTT). Fe₃O₄, Au, polydopamine (PDA), transition metal sulfides (TM sulfides), carbon, and graphene are the commonly used photothermal materials. NIR light used in biomedical applications normally includes the NIR‐I (750–900 nm) and NIR‐II (1000–1700 nm) regions. B) Photodynamic therapy (PDT). Two types of ROS can be generated from the PDT process: type‐I (^•OH, O₂ ^•− and H₂O₂) and type‐II (¹O₂). Upconversion nanoparticles (UCNPs) are promising to be integrated into the MNMs to achieve efficient PDT treatment. C) Drug delivery and release. Magnetic or acoustic fields are utilized to actuate the LMNM, and the light source is used to trigger the drug release.