Versatile synthesis of hollow PDA motors by interfacial protection

Micro/nanomotors (MNMs) are miniaturized devices capable of autonomous motion and on-demand task execution, which have broad application prospects in environmental remediation and biomedicine. However, miniaturization makes it difficult for chemically driven MNMs to integrate functional parts to perform tasks in a simple way. Here, we present a novel approach to manufacture asymmetric, hollow, modifiable and catalytic micromotors by the interfacial protection of polystyrene (PS) and inherent property of polydopamine (PDA). The hollow PDA microparticle with a single hole on its surface, as the main structure of the micromotors, is fabricated by swelling-induced symmetry breaking. Due to interfacial protection of PS, the functional component platinum nanoparticle (PtNP) can be selectively assembled on the outer or inner of the hollow PDA particle, respectively. Benefiting from the geometric shape and composition characteristics, PtNP-modified PDA motors can perform self-propulsion and catalyze the decomposition of methylene blue (MB) during motion. Moreover, the successful loading of nanoparticles with different functions (AuNP, Fe3O4 and MnO2) enables it to fabricate different functional MNMs as required. In short, the strategy is a versatile, general for designing asymmetric hollow MNMs with adjustable function by virtue of interfacial protection and functionalized PDA.