Abstract

While study in the field of polymer mechanochemistry has yielded mechanophores that perform various chemical reactions in response to mechanical stimuli, there is not yet a triggering method compatible with biological systems. Applications such as using mechanoluminescence to generate localized photon flux in vivo for optogenetics would greatly benefit from such an approach. Here we introduce a method of triggering mechanophores by using high-intensity focused ultrasound (HIFU) as a remote energy source to drive the spatially and temporally resolved mechanicalto- chemical transduction of mechanoresponsive polymers. A HIFU setup capable of controlling the excitation pressure, spatial location, and duration of exposure is employed to activate mechanochemical reactions in a cross-linked elastomeric polymer in a noninvasive fashion. One reaction is the chromogenic isomerization of a naphthopyran mechanophore embedded in a polydimethylsiloxane (PDMS) network. Under HIFU irradiation evidence of the mechanochemical transduction is the observation of a reversible color change as expected for the isomerization. The elastomer exhibits this distinguishable color change at the focal spot, depending on ultrasonic exposure conditions. A second reaction is the demonstration that HIFU irradiation successfully triggers a luminescent dioxetane, resulting in localized generation of visible blue light at the focal spot. In contrast to conventional stimuli such as UV light, heat, and uniaxial compression/tension testing, HIFU irradiation provides spatiotemporal control of the mechanochemical activation through targeted but noninvasive ultrasonic energy deposition. Targeted, remote light generation is potentially useful in biomedical applications such as optogenetics where a light source is used to trigger a cellular response.

Original languageEnglish (US)
Pages (from-to)10214-10222
Number of pages9
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number21
DOIs
StatePublished - Jan 1 2019

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Elastomers
Optogenetics
Polymers
Light
Ultrasonics
Color
Ultraviolet Rays
Photons
Hot Temperature
Observation
Pressure

Keywords

  • high-intensity focused ultrasound
  • mechanochromism
  • mechanoluminescence
  • mechanophores
  • spatiotemporal control

ASJC Scopus subject areas

  • General

Cite this

High-intensity focused ultrasound-induced mechanochemical transduction in synthetic elastomers. / Kim, Gun; Lau, Vivian M.; Halmes, Abigail J.; Oelze, Michael L; Moore, Jeffrey S; Li, King C.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 116, No. 21, 01.01.2019, p. 10214-10222.

Research output: Contribution to journalArticle

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