Abstract
The incorporation of molecular switches into polymer networks has been a powerful approach for the development of functional polymer materials that display macroscopic actuation and function enabled directly by molecular changes. However, such materials sometimes require harsh conditions to perform their functions, and the design of new molecular photoswitches that can function under physiological conditions is highly needed. Here, we report the design and synthesis of a spiropyridine-based photoswitchable hydrogel that exhibits light-driven actuation at physiological pH. Owing to its high pKa, spiropyridine maintains its ring-open protonated form at neutral pH, and the resulting hydrogel remains in a swollen state. Upon irradiation with visible light, the ring closure of spiropyridine leads to a decrease in the charge and a reduction in the volume of the hydrogel. The contracted gel could spontaneously recover to its expanding state in the dark, and this process is highly dynamic and reversible when the light is switched on and off. Furthermore, the hydrogel shows switchable fluorescence in response to visible light. Bending deformation is observed in the hydrogel thin films upon irradiation from one side. Importantly, the independence of this spiropyridine hydrogel from the acidic environment makes it biotolerant and shows excellent biocompatibility. This biocompatible spiropyridine hydrogel might have important biorelated applications in the future.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Data Availability Statement
The data that support the findings of this study are available within this article (and its Supplementary Information files).
References
Quan, H.; Kisailus, D.; Meyers, M. A. Hydration-induced reversible deformation of biological materials. Nat. Rev. Mater. 2020, 6, 264–283.
Kulbay, M.; Wu, K. Y.; Truong D.; Tran, S. D. Smart molecules in ophthalmology: hydrogels as responsive systems for ophthalmic applications. Smart molecules 2024, 2, e20230021.
Yuk, H.; Wu, J.; Zhao, X. Hydrogel interfaces for merging humans and machines. Nat. Rev. Mater. 2022, 7, 935–952.
Thambi, T.; Jung, J. M.; Lee, D. S. Recent strategies to develop phsensitive injectable hydrogels. Biomater. Sci. 2023, 11, 1948–1961.
Guo, B.; Liang, Y.; Dong, R. Physical dynamic double-network hydrogels as dressings to facilitate tissue repair. Nat. Protoc. 2023, 18, 3322–3354.
Chen, S.; Yang, L.; Leung, F. K.-C.; Kajitani, T.; Stuart, M. C. A.; Fukushima, T.; van Rijn, P.; Feringa, B. L. Photoactuating artificial muscles of motor amphiphiles as an extracellular matrix mimetic scaffold for mesenchymal stem cells. J. Am. Chem. Soc. 2022, 144, 3543–3553.
Matsuda, T.; Kawakami, R.; Namba, R.; Nakajima, T.; Gong, J. P. Mechanoresponsive self-growing hydrogels inspired by muscle training. Science 2019, 363, 504–508.
Zhao, Y.; Xuan, C.; Qian, X.; Alsaid, Y.; Hua, M.; Jin, L.; He, X. Soft phototactic swimmer based on self-sustained hydrogel oscillator. Sci. Rob. 2019, 4, eaax7112.
Jiao, D.; Zhu, Q. L.; Li, C. Y.; Zheng, Q.; Wu, Z. L. Programmable morphing hydrogels for soft actuators and robots: from structure designs to active functions. Acc. Chem. Res. 2022, 55, 1533–1545.
Liu, X.; Gao, M.; Chen, J.; Guo, S.; Zhu, W.; Bai, L.; Zhai, W.; Du, H.; Wu, H.; Yan, C.; Shi, Y.; Gu, J.; Qi, H. J.; Zhou, K. Recent advances in stimuli-responsive shape-morphing hydrogels. Adv. Funct. Mater. 2022, 32, 2203323.
Zhang, Y.; Liu, K.; Liu, T.; Ni, C.; Chen, D.; Guo, J.; Liu, C.; Zhou, J.; Jia, Z.; Zhao, Q.; Pan, P.; Xie, T. Differential diffusion driven far-from-equilibrium shape-shifting of hydrogels. Nat. Commun. 2021, 12, 6155.
Sun, Y.; Le, X.; Zhou, S.; Chen, T. Recent progress in smart polymeric gel-based information storage for anti-counterfeiting. Adv. Mater. 2022, 34, 2201262.
Gevorkian, A.; Morozova, S. M.; Kheiri, S.; Khuu, N.; Chen, H.; Young, E.; Yan, N.; Kumacheva, E. Actuation of three-dimensional-printed nanocolloidal hydrogel with structural anisotropy. Adv. Funct. Mater. 2021, 31, 2010743.
Hu, L.; Chee, P. L.; Sugiarto, S.; Yu, Y.; Shi, C.; Yan, R.; Yao, Z.; Shi, X.; Zhi, J.; Kai, D.; Yu, H. D.; Huang, W. Hydrogel-based flexible electronics. Adv. Mater. 2023, 35, 2205326.
Zhou, S. W.; Yu, C.; Chen, M.; Shi, C. Y.; Gu, R.; Qu, D. H. Self-healing and shape-shifting polymers controlled by dynamic bonds. Smart Molecules 2023, 1, e20220009.
Li, Q.; Schenning, A. P. H. J.; Bunning, T. J. Light-responsive smart soft matter technologies. Adv. Opt. Mater. 2019, 7, 1901160.
Li, L.; Scheiger, J. M.; Levkin, P. A. Design and applications of photoresponsive hydrogels. Adv. Mater. 2019, 31, 1807333.
Cong, L.; Chuang, L. Molecular design of photoresponsive hydrogels for biomimetic actuation. J. Funct. Polym. 2023, 36, 185–202.
Zheng, Y.; Li, C. Photothermally driven oxazine hydrogel actuators at the water-air interface. Giant 2023, 16, 100192.
Goulet-anssens, A.; Eisenreich, F.; Hecht, S. Enlightening materials with photoswitches. Adv. Mater. 2020, 32, 1905966.
Li, C.; Kazem-Rostami, M.; Seale, J. S. W.; Zhou, S.; Stupp, S. I. Macroscopic actuation of bisazo hydrogels driven by molecular photoisomerization. Chem. Mater. 2023, 35, 3923–3930.
Shang, H.; Le, X.; Sun, Y.; Shan, F.; Wu, S.; Zheng, Y.; Li, D.; Guo, D.; Liu, Q.; Chen, T. Integrating photorewritable fluorescent information in shape-emory organohydrogel toward dual encryption. Adv. Opt. Mater. 2022, 10, 2200608.
Cao, J.; Zhang, D.; Zhou, Y.; Zhang, Q.; Wu, S. Controlling properties and functions of polymer gels using photochemical reactions. Macromol. Rapid Commun. 2022, 43, 2100703.
Xu, F.; Feringa, B. L. Photoresponsive supramolecular polymers: from light-ontrolled small molecules to smart materials. Adv. Mater. 2023, 35, 2204413.
Iwaso, K.; Takashima, Y.; Harada, A. Fast response dry-type artificial molecular muscles with [c2]daisy chains. Nat.Chem. 2016, 8, 625–632.
Gu, Y.; Alt, E. A.; Wang, H.; Li, X.; Willard, A. P.; Johnson, J. A. Photoswitching topology in polymer networks with metal-organic cages as crosslinks. Nature 2018, 560, 65–69.
Li, Z. Y.; Liu, Y. Y.; Li, Y. J.; Wang, W.; Song, Y.; Zhang, J.; Tian, H. High-preservation single-cell operation through a photoresponsive hydrogel-nanopipette system. Angew. Chem. Int. Ed. 2021, 60, 5157–5161.
Ziółkowski, B.; Florea, L.; Theobald, J.; Benito-Lopez, F.; Diamond, D. Self-protonating spiropyran-co-nipam-co-acrylic acid hydrogel photoactuators. Soft Matter 2013, 9, 8754.
Chen, J.; Leung, F. K. C.; Stuart, M. C. A.; Kajitani, T.; Fukushima, T.; van der Giessen, E.; Feringa, B. L. Artificial muscle-like function from hierarchical supramolecular assembly of photoresponsive molecular motors. Nat. Chem. 2017, 10, 132–138.
Li, C.; Iscen, A.; Palmer, L. C.; Schatz, G. C.; Stupp, S. I. Light-driven expansion of spiropyran hydrogels. J. Am. Chem. Soc. 2020, 142, 8447–8453.
Li, C.; Lau, G. C.; Yuan, H.; Aggarwal, A.; Dominguez, V. L.; Liu, S.; Sai, H.; Palmer, L. C.; Sather, N. A.; Pearson, T. J.; Freedman, D. E.; Amiri, P. K.; Cruz, M. O. d. l.; Stupp, S. I. Fast and programmable locomotion of hydrogel-metal hybrids under light and magnetic fields. Sci. Robot. 2020, 5, eabb9822.
Hu, Y.; Ji, Q.; Huang, M.; Chang, L.; Zhang, C.; Wu, G.; Zi, B.; Bao, N.; Chen, W.; Wu, Y. Light-driven self-oscillating actuators with phototactic locomotion based on black phosphorus heterostructure. Angew. Chem. Int. Ed. 2021, 60, 20511–20517.
Li, C.; Xue, Y.; Han, M.; Palmer, L. C.; Rogers, J. A.; Huang, Y.; Stupp, S. I. Synergistic photoactuation of bilayered spiropyran hydrogels for predictable origami-like shape change. Matter 2021, 4, 1377–1390.
Liao, Y. Design and applications of metastable-state photoacids. Acc. Chem. Res. 2017, 50, 1956–1964.
Elgattar, A.; Alghazwat, O.; Brown, A. B.; Bryantsev, V. S.; Bocharova, V.; Liao, Y. Photoreaction of indazole metastable-state photoacid. J. Photoch. Photobio. A 2023, 439, 114599.
Premadasa, U. I.; Bocharova, V.; Miles, A. R.; Stamberga, D.; Belony, S.; Bryantsev, V. S.; Elgattar, A.; Liao, Y.; Damron, J. T.; Kidder, M. K.; Doughty, B.; Custelcean, R.; Ma, Y. Z. Photochemically driven CO2 release using a metastable-state photoacid for energy efficient direct air capture. Angew. Chem. Int. Ed. 2023, 62, e202304957.
Abeyrathna, N.; Liao, Y. A reversible photoacid functioning in PBS buffer under visible light. J. Am. Chem. Soc. 2015, 137, 11282–11284.
Elgattar, A.; Abeyrathna, N.; Liao, Y. Localized pH pulses in pbs buffer repeatedly induced by visible light. J. Phys. Chem. B 2019, 123, 648–654.
Alghazwat, O.; Elgattar, A.; Alharithy, H.; Liao, Y. A reversible photoacid switched by different wavelengths of light. ChemPhotoChem 2021, 5, 376–380.
Li, C.; Iscen, A.; Sai, H.; Sato, K.; Sather, N. A.; Chin, S. M.; Álvarez, Z.; Palmer, L. C.; Schatz, G. C.; Stupp, S. I. Supramolecular-covalent hybrid polymers for light-activated mechanical actuation. Nat. Mater. 2020, 19, 900–909.
Berton, C.; Busiello, D. M.; Zamuner, S.; Solari, E.; Scopelliti, R.; Fadaei-Tirani, F.; Severin, K.; Pezzato, C. Thermodynamics and kinetics of protonated merocyanine photoacids in water. Chem. Sci. 2020, 11, 8457.
Wimberger, L.; Prasad, S. K. K.; Peeks, M. D.; Andréasson, J.; Schmidt, T. W.; Beves, J. E. Large, tunable, and reversible pH changes by merocyanine photoacids. J. Am. Chem. Soc. 2021, 143, 20758.
Yang, X.; Shi, W.; Chen, Z.; Du, M.; Xiao, S.; Qu, S.; Li, C. Light-fueled nonequilibrium and adaptable hydrogels for highly tunable autonomous self-oscillating functions. Adv. Funct. Mater. 2023, 33, 2214394.
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.
Acknowledgments
This work was financially supported by the National Natural Science Foundation of China (No. 52373121), the National Key R&D Program of China (No. 2022YFA1305100) and the Natural Science Foundation of Anhui Province (No. 2208085MB27).
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
The authors declare no interest conflict.
Electronic Supplementary Information
Rights and permissions
About this article
Cite this article
Liao, C., Du, MQ. & Li, C. Photoswitchable Spiropyridine Enabled Photoactuation of Polymeric Hydrogels under Physiological pH Conditions. Chin J Polym Sci (2024). https://doi.org/10.1007/s10118-024-3211-8
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s10118-024-3211-8