Electric-Field-Guided Precision Manipulation of Catalytic Nanomotors for Cargo Delivery and Powering Nanoelectromechanical Devices

Abstract

ABSTRACT:We report a controllable and precision approach in manipulating catalytic nanomotors by strategically applied electric (E-) fields in three dimensions (3-D). With the high controllability, the catalytic nanomotors have demonstrated new versatility in capturing, delivering, and releasing of cargos to designated locations as well as in-situ integration with nanomechanical devices (NEMS) to chemically power the actuation. With combined AC and DC E-fields, catalytic nanomotors can be accurately aligned by the AC E-fields and instantly change their speeds by the DC E-fields. Within the 3-D orthogonal microelectrode sets, the in-plane transport of catalytic nanomotors can be swiftly turned on and off, and these catalytic nanomotors can also move in the vertical direction. The interplaying nanoforces that govern the propulsion and alignment are investigated. The modeling of catalytic nanomotors proposed in previous works has been confirmed quantitatively here. Finally, the prowess of the precision manipulation of catalytic nanomotors by E-fields is demonstrated in two applications: the capture, transport, and release of cargos to pre-patterned microdocks, and the assembly of catalytic nanomotors on NEMS to power the continuous rotation. The innovative concepts and approaches reported in this work could further advance ideal applications of catalytic nanomotors, e.g. for assembling and powering nanomachines, nanorobots, and complex NEMS devices.

Enzymatic Micromotors as a Mobile Photosensitizer Platform for Highly Efficient On‐Chip Targeted Antibacteria Photodynamic Therapy

“…[13][14][15] In particular, MNMs as active carriers with the capability of cargo loading and controllable motion have great potentials for effective delivery of different types of cargos. [15] So far, researchers have also explored stimuli-responsive materials, [16][17][18][19] biomimetic materials, [20][21][22] and micro-organisms functionalized with nanomaterials [23] as MNMs to precisely transport cargos of drugs, [16,20,23,24] proteins, [18,22,25] and genes [19] in vitro and/or in vivo. Compared with traditional passive delivery, MNMs can perform tasks such as controlled navigation, rapid transportation, and active delivery of payloads to disease sites, and thus have paved way for on demand biomedical cargo transportation.…”

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Photodynamic therapy (PDT) functions when the light-excited photosensitizers transfer energy to oxygen molecules ( 3 O 2 ) to produce cytotoxic singlet oxygen ( 1 O 2 ) that can effectively kill cells or bacteria. [15] So far, researchers have also explored stimuli-responsive materials, [16][17][18][19] biomimetic materials, [20][21][22] and micro-organisms functionalized with nanomaterials [23] as MNMs to precisely transport cargos of drugs, [16,20,23,24] proteins, [18,22,25] and genes [19] in vitro and/or in vivo. Herein, an enzymatic micromotor based on hollow mesoporous SiO 2 (mSiO 2 ) microspheres is constructed as a mobile and highly efficient photosensitizer platform.

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Fabrication of Self‐Propelled Micro‐ and Nanomotors Based on Janus Structures

“…Other Pt/Au nanorods of 370 nm in diameter and 1 mmP ta nd 1 mmA ui nl ength were synthesized by using a similarp rocess ( Figure 6A). [33] The nanomotors were aligned by the alternating current (AC) electric fields and immediately alteredt heir speeds in the presenceo fd irect current (DC)electric fields. These nanomotors could produce an electric field that resulted in attractive and repulsive interactions.…”

“…Furthermore, precise control of bimetal nanorods was achieved by electric fields. [33] The nanomotors were aligned by the alternating current (AC) electric fields and immediately alteredt heir speeds in the presenceo fd irect current (DC)electric fields.…”

Electrophoresis of active Janus particles

“…Electrical properties of most catalytic micromotors 6,42,50 suggest that an electric field can be an alternative or even better candidate to control the motion of self-phoretic particles. Moreover, pick-up and release of cargos through induced dipolar interactions between a Janus motor and the cargos can be achieved more easily by applying an electric field rather than other tools 11,73 . In this regards, the electrophoresis of catalytic Janus particles have been investigated experimentally in Ref.…”