Motion Control of Polymeric Nanomotors Based on Host–Guest Interactions

• Published in: Angewandte Chemie International Edition Vol. 58; no. 26; pp. 8687 - 8691
• Main Authors: Tu, Yingfeng, Peng, Fei, Heuvelmans, Josje M., Liu, Shuwen, Nolte, Roeland J. M., Wilson, Daniela A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 24-06-2019
• Edition: International ed. in English
• Subjects: Block copolymers; Cyclodextrins; Diffusion rate; Drug delivery; Drug delivery systems; Fuels; host–guest interaction; Hydrogen peroxide; Inclusion complexes; Irradiation; Isomers; Light irradiation; light responsiveness; Motion control; Motors; nanomotors; Nanoparticles; Platinum; Radiation; β-Cyclodextrin; light responsiveness; host-guest interaction; motion control; nanomotors
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201900917

Controlling the motion of artificial self‐propelled micro‐ and nanomotors independent of the fuel concentration is still a great challenge. Here we describe the first report of speed manipulation of supramolecular nanomotors via blue light‐responsive valves, which can regulate the access of hydrogen peroxide fuel into the motors. Light‐sensitive polymeric nanomotors are built up via the self‐assembly of functional block copolymers, followed by bowl‐shaped stomatocyte formation and incorporation of platinum nanoparticles. Subsequent addition of β‐cyclodextrin (β‐CD) leads to the formation of inclusion complexes with the trans‐isomers of the azobenzene derivatives grafted from the surfaces of the stomatocytes. β‐CDs attachment decreases the diffusion rate of hydrogen peroxide into the cavities of the motors because of partly blocking of the openings of the stomatocyte. This results in a lowering of the speed of the nanomotors. Upon blue light irradiation, the trans‐azobenzene moieties isomerize to the cis‐form, which lead to the detachment of the β‐CDs due to their inability to form complexes with the cis‐isomer. As a result, the speed of the nanomotors increases accordingly. Such a conformational change provides us with the unique possibility to control the speed of the supramolecular nanomotor via light‐responsive host–guest complexation. We envision that such artificial responsive nano‐systems with controlled motion could have potential applications in drug delivery.
Azobenzene is introduced to facilitate the binding of β‐cyclodextrins with high steric hindrance to nanomotors. This results in lowering diffusion of hydrogen peroxide and decreased motion. Upon light irradiation, formed cis‐azobenzene leads to the detachment of β‐cyclodextrins due to their inability to form complexes with the cis‐isomer. As a result, the speed of the nanomotors increases accordingly.