Natural organisms have evolved highly specialized morphologies and behaviors to adapt to their intricately changing habitats. By translating these biological inspirations into artificial designs, scientists have sought to replicate the remarkable efficiency and versatility observed in nature. The suckerfish-shark relationship serves as a compelling model: suckerfishes cling to sharks or boats during transit but detach upon arrival in prey-rich waters to forage independently. Mimicking this dynamic behavior, the researchers engineered a core-satellite micro@nanomotor system that operates through two distinct stages—a large micromotor host carrying numerous small nanomotor satellites, which release selectively in response to environmental pH changes.

At the heart of this system is a yolk-shell structured micromotor composed of polydopamine-mesoporous silica (PDA-MS), which acts as the “host.” This core is functionalized with many Janus gold-platinum (Au-Pt) nanomotors—analogous to the “suckerfish” satellites—that are capable of autonomous propulsion driven by hydrogen peroxide (H₂O₂) decomposition. The coordinated bonding between the nanomotors and the PDA-MS surface is sensitive to weakly acidic conditions, allowing the nanomotors to detach precisely when the micro@nanomotor encounters specific chemical cues.

The micro@nanomotor achieves directional motion by exploiting self-thermophoresis when illuminated with low-power NIR light. This photothermal effect generates a localized temperature gradient, propelling the micromotor host along a predetermined path. Upon encountering a weakly acidic microenvironment, similar to tumor extracellular spaces, the coordinated bonds weaken, triggering the release of the active nanomotors. Once released, these smaller nanomotors engage in self-diffusiophoretic movement fueled by the low concentrations of hydrogen peroxide present, enabling independent navigation and enhanced coverage at the target site.

This innovative two-stage propulsion mechanism represents a profound leap in micro/nanorobotics, combining remote light actuation with environmentally responsive release. The bionic design strategy addresses a long-standing challenge in the field: developing flexible micro/nanomotors capable of adapting to and functioning within the diverse, complex biological milieus encountered in vivo. Such responsiveness is critical for performing sophisticated tasks such as targeted drug delivery, biosensing, and environmental detoxification, where precise control over motor behavior and cargo release is paramount.

Moreover, the core-satellite architecture allows for a high payload capacity of functional nanomotors loaded onto a single micromotor platform. This hierarchical system maximizes efficiency by enabling the controlled liberation of numerous Janus nanomotors at the site of interest, vastly improving the potential for targeted therapeutic applications. In particular, the researchers propose that this system could be adapted for theranostic functions within tumor microenvironments, where the mild acidity acts as a natural trigger for motor deployment and therapeutic payload release.

Fundamentally, the incorporation of Janus nanomotors—named for their dual-faced asymmetric design—provides directional propulsion through catalytic decomposition of low-concentration hydrogen peroxide fuel, generating localized chemical gradients. By decorating the PDA-MS micromotor surface with these Janus nanomotors via coordinated bonds sensitive to pH, the team creates a responsive system that can switch propulsion modes seamlessly. This adaptability enhances operational flexibility in fluctuating biological or chemical environments, overcoming critical limitations of conventional unistage micro/nanomotor systems.

The research, supported by major funding bodies including China’s Fundamental Research Funds for the Central Universities and the Natural Science Foundation of Jiangsu Province, represents a significant milestone in artificial micro/nanomotor engineering. It also highlights the synergy between biomimetic design principles and advanced materials chemistry in constructing functional devices with high intelligence and autonomy. Such advancements pave the way for next-generation smart nanomachines that intelligently interact with biological systems for applications spanning precision medicine, diagnostics, and beyond.

Professor Xin Du, the lead scientist on this project, emphasized the transformative potential of integrating biologically inspired motion strategies with smart material components. According to Du, the ability to remotely control micromotor motion via NIR light combined with environmentally triggered nanomotor release offers unprecedented operational versatility. His group’s extensive publication record across high-impact journals attests to their pioneering role in this rapidly evolving domain.

The prospects for this two-stage micro@nanomotor extend beyond medical applications. Environmental remediation stands to benefit from the autonomous release of numerous catalytic nanomotors capable of degrading pollutants, enhancing water treatment technologies, and monitoring environmental variables in situ. The responsive release mechanism enables a dynamic adaptation to contaminants, triggering motor deployment only when necessary, thus conserving fuel and avoiding unintended dispersal.

In the broader context, this breakthrough underscores the importance of investigating natural cooperative behaviors and translating them into engineered microsystems. By imitating the cooperative locomotive and release behaviors of marine species, researchers can overcome existing design challenges associated with control, fuel efficiency, and environmental adaptability in micro/nanomotors. This bench-to-nature approach signifies a new paradigm in the design of intelligent nanomachines and multifunctional therapeutic platforms.

As nanotechnology continues to push the frontiers of miniaturization and autonomy, such smart biomimetic micro@nanomotors herald a future where artificial systems not only coexist harmoniously within biological niches but actively respond and adapt to microenvironmental cues. The dynamic interplay between NIR light propulsion and chemical stimuli response in this system offers a versatile framework potentially extensible to other stimuli-responsive materials including enzymatic, magnetic, and acoustic modulation.

Ultimately, the core-satellite PDA-MS@Au-Pt micro@nanomotor system crafted by this research team represents a compelling synthesis of materials engineering, catalytic propulsion chemistry, and biomimetic design. It exemplifies the transformative impact of biologically inspired mechanisms powered by intelligent materials to realize multifunctional, adaptable, and controllable micro/nanomachines. As such, it opens new vistas for soft robotic devices capable of performing complex biological tasks with precision and minimal invasiveness.

Subject of Research: Biomimetic micro/nanomotors inspired by suckerfish-shark interaction for intelligent, two-stage propulsion and weak acid-triggered release of nanomotors.

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

News Publication Date: 7-Apr-2025

Web References: http://dx.doi.org/10.26599/NR.2025.94907309

Image Credits: Nano Research, Tsinghua University Press

Keywords

Biomimetic micro/nanomotors, two-stage propulsion, Janus nanomotors, near-infrared light propulsion, weak acid-triggered release, hydrogen peroxide decomposition, polydopamine-mesoporous silica, tumor microenvironment, smart nanomachines, self-thermophoresis, self-diffusiophoresis, active cargo delivery

Inspired by millions of years of biological evolution, marine organisms like mollusks construct protective shells composed of multiple mineralized layers, each optimized to endure different forms of mechanical force. Unlike homogeneous materials, these natural composites exhibit nonlinear and multistage responses to stress, allowing them to absorb and redirect energy in complex ways. Reproducing these qualities synthetically has been a persistent challenge, primarily due to the lack of precise control over individual layer behaviors and their interactions.

The team, led by Professor Shelly Zhang of the University of Illinois Urbana-Champaign’s Civil and Environmental Engineering department together with Ole Sigmund from the Technical University of Denmark, has pioneered an inverse design framework that programs both the material properties of individual layers and their microscale interconnections. This computationally driven approach enables a continuum setup where each layer’s nonlinear stress-strain response is meticulously optimized to not only perform in isolation but also to collaborate dynamically within the multilayered matrix, thereby greatly expanding the design space over previous methodologies relying on single layers or lattice-based structures.

Their study, recently published in Science Advances, details how the multilayered synthetic material exhibits extreme nonlinear behavior by undergoing programmed sequential buckling during mechanical loading. Traditional materials typically exhibit linear or monotonic deformation until failure, but this engineered material transitions through multiple well-defined mechanical phases, dissipating energy progressively. By harnessing the intrinsic coupling between layers, the system adapts its response level to the severity of the applied stress, mimicking the adaptive protective function seen in natural nacre.

A crucial aspect of this work lies in the computational simulation and modeling techniques employed to design the multilayered composites. The team used inverse design principles, a process where desired overall material behavior guides the iterative optimization of microstructural parameters and layer connections. This approach allowed them to decipher how to distribute stiffness, strength, and buckling thresholds across layers to realize a collective, nonlinear response unheard of in single-material designs.

Fabricating such intricately programmed materials presented formidable challenges. Theoretically, the design targets an infinitely periodic structure to maximize the consistency of mechanical response, but practical fabrication is limited to finite unit assemblies. This difference between theory and reality manifested as observable discrepancies in buckling sequences and deformation patterns during experimental validation. However, rather than viewing these variations as setbacks, the team cleverly exploited them as embedded information carriers, effectively encoding mechanical data within the material’s response and enabling a feedback loop for further optimization.

Videos accompanying the research vividly illustrate the experimental processes, highlighting how each cellular component undergoes a distinct buckling event. This sequential activation not only spreads energy dissipation over time but also stores recoverable strain energy, an attribute vital for applications requiring reversible deformation or repeated impact resistance. By decoding this mechanical information, researchers can fine-tune layer interactions and program the assembly for targeted performance under specific conditions.

The potential applications of this technology are vast and transformative. Automotive safety could benefit from multilayered bumpers that adapt their energy absorption depending on collision severity, improving passenger protection while reducing material waste and repair costs. In wearable medical technology, bandages or supports made from such materials could dynamically adjust stiffness and compliance to protect injuries without compromising comfort or mobility, opening new frontiers in personalized healthcare.

Looking forward, scaling up the fabrication process remains a challenge due to the intricate microscale programming required. Nevertheless, the insights gained from this interdisciplinary collaboration underscore the power of collective work—both in biological systems and in human endeavors—and spotlight a new paradigm where engineered materials are no longer passive but actively responsive and programmable.

Professor Zhang emphasizes that the strength of the design lies in the synergy of layers acting in concert rather than isolation. This holistic material behavior transcends classical limits of material science and paves the way for a future where smart, adaptive materials can revolutionize countless industries. The research team’s work continues to bridge the boundary between biology-inspired design and advanced engineering, setting the stage for unprecedented innovation.

Moreover, the research highlights the critical role of microscale interconnections in dictating macroscopic material properties. Instead of relying solely on chemical composition or bulk geometry, the programmed interfaces between layers serve as mechanical communication pathways, coordinating responses to external stimuli. This insight opens new possibilities for multifunctional materials that can sense, adapt, and even recover from damage by leveraging embedded mechanical intelligence.

Lastly, this study exemplifies the fertile ground where computational modeling meets experimental fabrication. By closing the loop between design, synthesis, and testing, the researchers established a robust methodology capable of iteratively improving material performance. This approach not only accelerates material discovery but also establishes a new toolkit for engineering the next generation of smart composites tailored for specific, dynamic applications.

The University of Illinois Urbana-Champaign, known for its cutting-edge engineering research and interdisciplinary collaboration, continues to lead in the quest to mimic and surpass nature’s materials by transforming ancient biological wisdom into futuristic technologies.

Subject of Research: Multilayered synthetic materials with programmable nonlinear mechanical responses inspired by natural nacre.

Article Title: Extreme nonlinearity by layered materials through inverse design.

News Publication Date: 16-May-2025.

Web References:

• Study DOI: 10.1126/sciadv.adr6925
• Prof. Shelly Zhang Profile: https://cee.illinois.edu/directory/profile/zhangxs
• University of Illinois Urbana-Champaign Civil and Environmental Engineering: https://cee.illinois.edu/

References:
Zhang, S., Sigmund, O., et al. (2025). Extreme nonlinearity by layered materials through inverse design. Science Advances, DOI: 10.1126/sciadv.adr6925.

Image Credits: Photo by Fred Zwicky.

Keywords: biomimicry, multilayered materials, synthetic nacre, nonlinear mechanics, inverse design, programmable composites, energy absorption, mechanical buckling, adaptive materials, material optimization, computational modeling, microscale interconnections.