Light‐Induced Temperature Transitions in Biodegradable Polymer and Nanorod Composites

Abstract

Shape-memory materials (including polymers, metals, and ceramics) are those that are processed into a temporary shape and respond to some external stimuli (e.g., temperature) to undergo a transition back to a permanent shape.[1, 2] Shape memory polymers are finding use in a range of applications from aerospace to fabrics, to biomedical devices and microsystem components.[3–5] For many applications, it would be beneficial to initiate heating with an external trigger (e.g., transdermal light exposure). In this work, we formulated composites of gold nanorods (<1% by volume) and biodegradable networks, where exposure to infrared light induced heating and consequently, shape transitions. The heating is repeatable and tunable based on nanorod concentration and light intensity and the nanorods did not alter the cytotoxicity or in vivo tissue response to the networks.

Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms

“…They use these materials as heat-activated hinges attached to solid plates, and by varying the weight percentage of additives are able to adjust the response speed of petals opening on a model flower as a function of distance. Similar effects have been achieved by others using gold NP [155] and magnetite particles [109].…”

“…Finally, local amplification may derive from simple changes in colouration [200], or increased energy transmission induced by particles with a tailored surface plasmon resonance [155].…”

Emerging Strategies for Controlling Drug Release by Using Visible/Near IR Light

“…Once the NIR light irradiation was stopped, the polymer relaxed back to the original shape and consequently stopped the release of DOX. [27,28]. *A6: poly (β-aminoester) (PBAE) macromere, tBA: tert-butyl acrylate; HEA: 2-hydroxyethyl acrylate, and gold nanorod: 31 nm (length), 9.2 nm (width), and 3.6 (aspect ratio).…”

Responsive Biomaterials: Advances in Materials Based on Shape‐Memory Polymers

“…In cases where the temperature response of the SMP is above body temperature (e.g., MM5520 thermoplastic polyurethane) it is possible to trigger their shape-memory reversion with photothermal excitation as demonstrated for SMP-based stents; [4] the photothermal shapememory response has also been demonstrated with SMPs composites containing gold nanorods as SMP-based sutures, where light-induced heating of the nanorods triggers the SMP-based sutures to change shape and close a wound. [5] Other triggers employed in SMP-based materials include: solvent-polymer interactions (e.g., rehydration), electricity, light (e.g., photoisomerization), magnetism, sound, or indeed chemical stimuli that utilize redox switches, or reversible/dynamic covalent bonds (e.g., acylhydrazones, disulfides) and non-covalent bonds (e.g., supramolecular interactions, hydrogen bonds) engineered into the polymers. [3] Clearly, the successful translation of SMPbased materials from the laboratory to the clinic relies on their ability to respond to biocompatible triggering events, and examples of progress in this direction are highlighted below.…”