Biomimetic two-stage micro@nanomotor with weak acid-triggered release of nanomotors

Organisms in nature have developed distinctive morphologies, structures, components, behaviors, and functions to thrive in intricate natural environments. This inspiration from nature has influenced the design concepts, fabrication techniques, and applications of various artificial systems. Generally, nature-inspired design can be divided into five categories: morphology, structure, behavior, function, and their combination. Smart biomimetic design is very helpful and significant to explore new propulsion modes, superior functions and novel mechanisms for the smart construction of artificial micro/nanomotors with intelligence. The unique characteristics enable the nature-inspired micro/nanomotors to become a promising candidate for versatile applications such as cargo transportation, nanobiomedicine, sensing and environmental remediation. However, so far, it remains a challenge to design and fabricate biomimetic micro/nanomotors with high flexibility to perform complex tasks in complicated and changeable environments.

In this work, inspired by the suckerfishes (guest)-shark (host) motion behavior, they designed and prepared a kind of intelligent two-stage micro@nanomotor with weak acid-triggered release of nanomotor. When the suckerfishes, who clinged to the surface of large fish or the bottom of boat and marched with them, reached bait-rich waters, they detached from the host to engage in foraging behavior. Inspired by the suckerfishes-shark system, by the coordinated bond interaction, a large amount of Janus Au-Pt nanomotors with hydrogen peroxide (H₂O₂)-driven capacity, analogous to suckerfishes, were attached onto immovable yolk-shell structured polydopamine-mesoporous silica (PDA-MS) micromotor as the host to create two-stage PDA-MS@Au-Pt micro@nanomotor. PDA-MS@Au-Pt micro@nanomotor moved directionally by self-thermophoresis under the propulsion of NIR light with low power density. When the PDA-MS@Au-Pt entered into the weak acidic environment formed by a low concentration of H₂O₂, most small Au-Pt nanomotors were detached from the surface of PDA-MS due to the weak acidic sensitivity of the coordinated bond, and then performed self-diffusiophoresis in the environment containing a low concentration of H₂O₂ as a chemical fuel. This bionic intelligent system, which consists of a large-sized micromotor and lots of small-sized nanomotors, should provide a new insight for active two-stage cargo delivery. This biomimetic two-stage strategy may be applied as tumor weakly acidic microenvironment-responsive theranostic systems for in vivo cancer treatment. Core-satellites structure of PDA-MS@Au-Pt micro@nanomotors should be an efficient way to deliver a lot of functional Janus satellites into a targeted site.

This work was supported by Fundamental Research Funds for the Central Universities (FRF-BR-23-02B), China Postdoctoral Science Foundation (No. 2023M731408), Jiangsu Funding Program for Excellent Postdoctoral Talent (No. 2023ZB640), Jiangsu Province Capability Improvement Project through Science, technology and Education (Jiangsu Provincial Medical Key Discipline, ZDXK202222) and Natural Science Foundation of Jiangsu Province (No. BK20230731).

About the Authors

Dr. Xin Du is a full professor in the School of Chemistry and Biological Engineering, University of Science and Technology Beijing, China. His research interests focus on the smart micro/nanomotors, multifunctional nano-theranostic systems, and nano-reactors. Until now, he has published more than 100 papers in Angew. Chem. Int. Ed., Adv. Mater., ACS Nano, and Adv. Funct. Mater., with more than 9,000 citations. His research works have been highlighted multiple times on websites such as ACS Weekly PressPac, Materials Views, Chemistry View, Science Daily, and The Economist.

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 17 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2023 InCites Journal Citation Reports, its 2023 IF is 9.6 (9.0, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.