Localized Nanoscale Heating Leads to Ultrafast Hydrogel Volume-Phase Transition

• Type of Material: Article
• Authors: Jing Zhao, Emory University; Hanguan Su, Emory University; Gregory E. Vansuch, Emory University; Zheng Liu, Wuhan University; Khalid Salaita, Emory University; Richard Dyer, Emory University
• Language: English
• Date: 2019-01-01
• Publisher: American Chemical Society
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2018 American Chemical Society.
• Final Published Version (URL): http://dx.doi.org/10.1021/acsnano.8b07150
• Title of Journal or Parent Work: ACS Nano
• ISSN: 1936-0851
• Volume: 13
• Issue: 1
• Start Page: 515
• End Page: 525
• Grant/Funding Information: This project was supported in part by the Robert P. Apkarian Integrated Electron Microscopy Core.; K.S. and B.D. are grateful for support from the DARPA BTO (grant no. HR0011–16-2–0011); and from NIGMS (GM053640 to BD).
• Keywords: NANOPARTICLES; hydrogel; Physical Sciences; Chemistry, Multidisciplinary; Materials Science; dynamic light scattering; ELECTRON THERMALIZATION; infrared spectroscopy; Science & Technology - Other Topics; MECHANISM; DEHALOPEROXIDASE-HEMOGLOBIN; volume-phase transition; Materials Science, Multidisciplinary; DYNAMIC FORCE SPECTROSCOPY; TIME; Chemistry, Physical; BOND DYNAMICS; nanorods; transient absorption; Chemistry; TEMPERATURE-JUMP; Technology; PNIPAM; Nanoscience & Nanotechnology; KINETICS; Science & Technology
• Research Categories: Chemistry, Physical

Abstract

The rate of the volume-phase transition for stimuli-responsive hydrogel particles ranging in size from millimeters to nanometers is limited by the rate of water transport, which is proportional to the surface area of the particle. Here, we hypothesized that the rate of volume-phase transition could be accelerated if the stimulus is geometrically controlled from the inside out, thus facilitating outward water ejection. To test this concept, we applied transient absorption spectroscopy, laser temperature-jump spectroscopy, and finite-element analysis modeling to characterize the dynamics of the volume-phase transition of hydrogel particles with a gold nanorod core. Our results demonstrate that the nanoscale heating of the hydrogel particle core led to an ultrafast, 60 ns particle collapse, which is 2-3 orders of magnitude faster than the response generated from conventional heating. This is the fastest recorded response time of a hydrogel material, thus opening potential applications for such stimuli-responsive materials.