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Cai H, Tepermeister M, Yuan C, Silberstein MN. Regulating hydrogel mechanical properties with an electric field. MATERIALS HORIZONS 2025. [PMID: 40353712 DOI: 10.1039/d5mh00308c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2025]
Abstract
Stimuli-responsive polymeric materials have attracted significant attention due to their ability to change properties in response to various external stimuli. Using an electric field as the stimulus is of particular interest as it possesses the potential for seamless integration of materials with electronic systems. While many materials with electric field responsive actuation have an associated mechanical property change, it is beneficial to develop materials that exhibit mechanical property changes without accompanying significant shape deformation. To address this challenge, here we designed a semi-interpenetrating polymer network (semi-IPN) hydrogel system containing both polyelectrolytes and salt ions, which enables electric field induced changes in mechanical properties while minimizing actuation. We first successfully verified the viability of our design by removing salt ions through a diffusion-only method where we witnessed the stiffness increased to 4.5 times the initial value while still being highly deformable. After this, we applied an electric field to transport the salt ions out of the hydrogel, as shown by both Raman spectroscopy and scanning electron microscopy. We were able to show a time-dependent stiffness increase, the maximum of which was 5 times the original stiffness. We quantified ion transport and water-splitting in the hydrogel by both experiments and simulations. Following this, we showed functional system reversibility by reversing the direction of the current to reinject salt ions into the semi-IPN hydrogel and reducing its stiffness to below the initial value. It's worth noting that our simulations enable us to understand the governing mechanisms behind ion generation and salt transport that leads to mechanical property changes. Finally, we were able to fabricate a spatially variable stiffness haptic interface with our hydrogel, with demonstrated reversibility and cyclability. This research can possibly find applications in soft robotics and haptics and also inspire the development of bio-compatible electronics related devices.
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Affiliation(s)
- Hongyi Cai
- Materials Science and Engineering, Cornell University, Ithaca, New York, USA
| | - Max Tepermeister
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, USA.
| | - Chenyun Yuan
- Materials Science and Engineering, Cornell University, Ithaca, New York, USA
| | - Meredith N Silberstein
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, USA.
- Engineered Living Materials Institute, Cornell University, Ithaca, New York, USA
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Wu L, Liu Y, Yang W, Liu Z, Liu C, Yuan X, Zhang L, Ju J, Yao X. In Situ Stimuli Transfer in Multi-Environment Shape-Morphing Hydrogels Based on the Copolymer Between Spiropyran and Acrylic Acid. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2025; 12:e2416173. [PMID: 40051303 PMCID: PMC12061295 DOI: 10.1002/advs.202416173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2024] [Revised: 02/19/2025] [Indexed: 05/10/2025]
Abstract
Smart hydrogels are considered as close mimics to the functions of biological entities. However, the stimuli-responsive performance of hydrogels is often limited by the slow diffusion process during water exchange with the surrounding environment. Here, a homogenous hydrogel composed of a water-soluble spiropyran covalently attached to the polyacrylic acid network is reported. This hydrogel demonstrates rapid and reversible shape-morphing behavior in air, underwater, or in oil. The mechanism involves the reversible protonation of spiropyran triggered by light stimuli. The release/capture of protons regulates the local proton concentration near the carboxyl groups in the polyacrylic acid network, distinguishing it from existing stimuli-responsiveness based on bulk water diffusion. The environment-independent shape-morphing performance of the unique in-situ stimuli transfer process, resulting in local water transfer amongst parts of a single piece of hydrogel is attributed. Eventually, light-controlled reversible actuation of the hydrogel is demonstrated, offering exciting possibilities for applications in flexible electronics, and soft actuators/robots.
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Affiliation(s)
- Liwei Wu
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Yiming Liu
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Wenpei Yang
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Zejun Liu
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Cuiping Liu
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Xiaomin Yuan
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Lingling Zhang
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Jie Ju
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
| | - Xi Yao
- Key Lab for Special Functional Materials of Ministry of EducationSchool of Nanoscience and Materials EngineeringHenan UniversityKaifengHenan475004P. R. China
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Mahkam N, Ugurlu MC, Kalva SK, Aghakhani A, Razansky D, Sitti M. Multiorifice acoustic microrobot for boundary-free multimodal 3D swimming. Proc Natl Acad Sci U S A 2025; 122:e2417111122. [PMID: 39841149 PMCID: PMC11789062 DOI: 10.1073/pnas.2417111122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2024] [Accepted: 12/17/2024] [Indexed: 01/23/2025] Open
Abstract
The emerging new generation of small-scaled acoustic microrobots is poised to expedite the adoption of microrobotics in biomedical research. Recent designs of these microrobots have enabled intricate bioinspired motions, paving the way for their real-world applications. We present a multiorifice design of air-filled spherical microrobots that convert acoustic wave energy to efficient propulsion through a resonant encapsulated microbubble. These microrobots can swim boundary-free in three-dimensional (3D) space while switching between various frequency-dependent locomotion modes. We explore the locomotion dynamics of microrobots with diameters ranging from 10 μm to 100 μm, focusing on their boundary-free 3D swimming and multimodal locomotion in response to acoustic stimuli below 1 MHz. Further, we elucidate the dynamics of these microrobots, featuring a single multiorifice cavity, which contributes to complex acoustic streaming and facilitates swift, unrestricted movements. Finally, we demonstrate that incorporating microrobots with additional nickel and gold layers significantly enhances their steering and visibility in optoacoustic and ultrasound imaging, enabling the development of the next generation of microrobots in healthcare applications.
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Affiliation(s)
- Nima Mahkam
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart70569, Germany
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, ETH Zurich, Zurich8093, Switzerland
| | - Musab C. Ugurlu
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart70569, Germany
| | - Sandeep Kumar Kalva
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, ETH Zurich, Zurich8093, Switzerland
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich8057, Switzerland
| | - Amirreza Aghakhani
- Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart70569, Germany
| | - Daniel Razansky
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, ETH Zurich, Zurich8093, Switzerland
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich8057, Switzerland
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart70569, Germany
- School of Medicine, Koç University, Istanbul34450, Türkiye
- College of Engineering, Koç University, Istanbul34450, Türkiye
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Sun B, Liu K, Wu B, Sun S, Wu P. Low-Hysteresis and Tough Ionogels via Low-Energy-Dissipating Cross-Linking. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2408826. [PMID: 39210639 DOI: 10.1002/adma.202408826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 07/30/2024] [Indexed: 09/04/2024]
Abstract
Low-hysteresis merits can help polymeric gel materials survive from consecutive loading cycles and promote life span in many burgeoning areas. However, it is a big challenge to design low-hysteresis and tough polymeric gel materials, especially for ionogels. This can be attributed to the fact that higher viscosities of ionic liquids (ILs) would increase chain friction of polymeric gels and eventually dissipate large amounts of energy under deformation. Herein, a chemical design of ionogels is proposed to achieve low-hysteresis characteristics in both mechanical and electric aspects via hierarchical aggregates formed by supramolecular self-assembly of quadruple H-bonds in a soft IL-rich polymeric matrix. These self-assembled nanoaggregates not only can greatly reinforce the polymeric matrix and enhance resilience, but also exhibit low-energy-dissipating features under stress conditions, simultaneously benefiting for low-hysteresis properties. These aggregates can also promote toughness and subsequent anti-fatigue properties in response to external cyclic mechanical stimuli. More importantly, these ionogels are presented as a model system to elucidate the underlying mechanism of the low hysteresis and fatigue resistance. Based on these findings, it is further demonstrated that the supramolecular low-hysteresis strategy is universal.
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Affiliation(s)
- Bin Sun
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, National Engineering Research Center for Dyeing and Finishing of Textiles, Center for Advanced Low-dimension Materials, College of Chemistry and Chemical Engineering, Donghua University, Shanghai, 201620, China
| | - Kai Liu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, National Engineering Research Center for Dyeing and Finishing of Textiles, Center for Advanced Low-dimension Materials, College of Chemistry and Chemical Engineering, Donghua University, Shanghai, 201620, China
| | - Baohu Wu
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) Forschungszentrum Jülich, 85748, Garching, Germany
| | - Shengtong Sun
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, National Engineering Research Center for Dyeing and Finishing of Textiles, Center for Advanced Low-dimension Materials, College of Chemistry and Chemical Engineering, Donghua University, Shanghai, 201620, China
| | - Peiyi Wu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, National Engineering Research Center for Dyeing and Finishing of Textiles, Center for Advanced Low-dimension Materials, College of Chemistry and Chemical Engineering, Donghua University, Shanghai, 201620, China
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Luo R, Xiang X, Jiao Q, Hua H, Chen Y. Photoresponsive Hydrogels for Tissue Engineering. ACS Biomater Sci Eng 2024; 10:3612-3630. [PMID: 38816677 DOI: 10.1021/acsbiomaterials.4c00314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Hydrophilic and biocompatible hydrogels are widely applied as ideal scaffolds in tissue engineering. The "smart" gelation material can alter its structural, physiochemical, and functional features in answer to various endo/exogenous stimuli to better biomimic the endogenous extracellular matrix for the engineering of cells and tissues. Light irradiation owns a high spatial-temporal resolution, complete biorthogonal reactivity, and fine-tunability and can thus induce physiochemical reactions within the matrix of photoresponsive hydrogels with good precision, efficiency, and safety. Both gel structure (e.g., geometry, porosity, and dimension) and performance (like conductivity and thermogenic or mechanical properties) can hence be programmed on-demand to yield the biochemical and biophysical signals regulating the morphology, growth, motility, and phenotype of engineered cells and tissues. Here we summarize the strategies and mechanisms for encoding light-reactivity into a hydrogel and demonstrate how fantastically such responsive gels change their structure and properties with light irradiation as desired and thus improve their applications in tissue engineering including cargo delivery, dynamic three-dimensional cell culture, and tissue repair and regeneration, aiming to provide a basis for more and better translation of photoresponsive hydrogels in the clinic.
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Affiliation(s)
- Rui Luo
- Institute of Pharmacy & Pharmacology, School of Pharmaceutical Science, University of South China, Hengyang, Hunan 421001, China
| | - Xianjing Xiang
- Institute of Pharmacy & Pharmacology, School of Pharmaceutical Science, University of South China, Hengyang, Hunan 421001, China
| | - Qiangqiang Jiao
- Institute of Pharmacy & Pharmacology, School of Pharmaceutical Science, University of South China, Hengyang, Hunan 421001, China
| | - Hui Hua
- Institute of Pharmacy & Pharmacology, School of Pharmaceutical Science, University of South China, Hengyang, Hunan 421001, China
| | - Yuping Chen
- Institute of Pharmacy & Pharmacology, School of Pharmaceutical Science, University of South China, Hengyang, Hunan 421001, China
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Guo K, Yang X, Zhou C, Li C. Self-regulated reversal deformation and locomotion of structurally homogenous hydrogels subjected to constant light illumination. Nat Commun 2024; 15:1694. [PMID: 38402204 PMCID: PMC10894256 DOI: 10.1038/s41467-024-46100-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/14/2024] [Indexed: 02/26/2024] Open
Abstract
Environmentally adaptive hydrogels that are capable of reconfiguration in response to external stimuli have shown great potential toward bioinspired actuation and soft robotics. Previous efforts have focused mainly on either the sophisticated design of heterogeneously structured hydrogels or the complex manipulation of external stimuli, and achieving self-regulated reversal shape deformation in homogenous hydrogels under a constant stimulus has been challenging. Here, we report the molecular design of structurally homogenous hydrogels containing simultaneously two spiropyrans that exhibit self-regulated transient deformation reversal when subjected to constant illumination. The deformation reversal mechanism originates from the molecular sequential descending-ascending charge variation of two coexisting spiropyrans upon irradiation, resulting in a macroscale volumetric contraction-expansion of the hydrogels. Hydrogel film actuators were developed to display complex temporary bidirectional shape transformations and self-regulated reversal rolling under constant illumination. Our work represents an innovative strategy for programming complex shape transformations of homogeneous hydrogels using a single constant stimulus.
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Affiliation(s)
- Kexin Guo
- Key Laboratory of Precision and Intelligent Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine and i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei, 230026, China
| | - Xuehan Yang
- Key Laboratory of Precision and Intelligent Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Chao Zhou
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine and i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei, 230026, China
| | - Chuang Li
- Key Laboratory of Precision and Intelligent Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.
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Zhou H, Zhu Y, Yang B, Huo Y, Yin Y, Jiang X, Ji W. Stimuli-responsive peptide hydrogels for biomedical applications. J Mater Chem B 2024; 12:1748-1774. [PMID: 38305498 DOI: 10.1039/d3tb02610h] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Stimuli-responsive hydrogels can respond to external stimuli with a change in the network structure and thus have potential application in drug release, intelligent sensing, and scaffold construction. Peptides possess robust supramolecular self-assembly ability, enabling spontaneous formation of nanostructures through supramolecular interactions and subsequently hydrogels. Therefore, peptide-based stimuli-responsive hydrogels have been widely explored as smart soft materials for biomedical applications in the last decade. Herein, we present a review article on design strategies and research progress of peptide hydrogels as stimuli-responsive materials in the field of biomedicine. The latest design and development of peptide hydrogels with responsive behaviors to stimuli are first presented. The following part provides a systematic overview of the functions and applications of stimuli-responsive peptide hydrogels in tissue engineering, drug delivery, wound healing, antimicrobial treatment, 3D cell culture, biosensors, etc. Finally, the remaining challenges and future prospects of stimuli-responsive peptide hydrogels are proposed. It is believed that this review will contribute to the rational design and development of stimuli-responsive peptide hydrogels toward biomedical applications.
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Affiliation(s)
- Haoran Zhou
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.
| | - Yanhua Zhu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.
| | - Bingbing Yang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.
| | - Yehong Huo
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.
| | - Yuanyuan Yin
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Stomatological Hospital of Chongqing Medical University, Chongqing 401147, P. R. China
| | - Xuemei Jiang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.
| | - Wei Ji
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.
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