Issue 40, 2020

Dynamic, multimodal hydrogel actuators using porphyrin-based visible light photoredox catalysis in a thermoresponsive polymer network

Abstract

Hydrogels that can respond to multiple external stimuli represent the next generation of advanced functional biomaterials. Here, a series of multimodal hydrogels were synthesized that can contract and expand reversibly over several cycles while changing their mechanical properties in response to blue and red light, as well as heat (∼50 °C). The light-responsive behavior was achieved through a photoredox-based mechanism consisting of photoinduced electron transfer from a zinc porphyrin photocatalyst in its excited state to oligoviologen-based macrocrosslinkers, both of which were integrated into the hydrogel polymer network during gel formation. Orthogonal thermoresponsive properties were also realized by introducing N-isopropyl acrylamide (NIPAM) monomer simultaneously with hydroxyethyl acrylate (HEA) in the pre-gel mixture to produce a statistical 60 : 40 HEA : NIPAM polymer network. The resultant hydrogel actuators – crosslinked with either a styrenated viologen dimer (2V4+-St) or hexamer (6V12+-St) – were exposed to red or blue light, or heat, for up to 5 h, and their rate of contraction, as well as the corresponding changes in their physical properties (i.e., stiffness, tensile strength, Young's modulus, etc.), were measured. The combined application of blue light and heat to the 6V12+-St-based hydrogels was also demonstrated, resulting in hydrogels with more than two-fold faster contraction kinetics and dramatically enhanced mechanical robustness when fully contracted. We envision that the reported materials and the corresponding methods of remotely manipulating the dynamic hydrogels may serve as a useful blueprint for future adaptive materials used in biomedical applications.

Graphical abstract: Dynamic, multimodal hydrogel actuators using porphyrin-based visible light photoredox catalysis in a thermoresponsive polymer network

Supplementary files

Article information

Article type
Edge Article
Submitted
05 Aug 2020
Accepted
01 Sep 2020
First published
03 Sep 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2020,11, 10910-10920

Dynamic, multimodal hydrogel actuators using porphyrin-based visible light photoredox catalysis in a thermoresponsive polymer network

F. Amir, X. Li, M. C. Gruschka, N. D. Colley, L. Li, R. Li, H. R. Linder, S. A. Sell and J. C. Barnes, Chem. Sci., 2020, 11, 10910 DOI: 10.1039/D0SC04287K

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