Polymer Mechanochemistry in Microbubbles

Abstract

Polymer mechanochemistry is a promising technology to convert mechanical energy into chemical functionality by breaking covalent and supramolecular bonds site‐selectively. Yet, the mechanochemical reaction rates of covalent bonds in typically used ultrasonication setups lead to reasonable conversions only after comparably long sonication times. This can be accelerated by either increasing the reactivity of the mechanoresponsive moiety or by modifying the encompassing polymer topology. Here, a microbubble system with a tailored polymer shell consisting of an N2 gas core and a mechanoresponsive disulfide‐containing polymer network is presented. It is found that the mechanochemical activation of the disulfides is greatly accelerated using these microbubbles compared to commensurate solid core particles or capsules filled with liquid. Aided by computational simulations, it is found that low shell thickness, low shell stiffness and crosslink density, and a size‐dependent eigenfrequency close to the used ultrasound frequency maximize the mechanochemical yield over the course of the sonication process.This article is protected by copyright. All rights reserved

Mechanochemical Activation of DNAzyme by Ultrasound

“…[36,37] Although this was a significant improvement compared to 20 kHz US for potential biocompatibility, the inherent reliance on inertial cavitation will prohibit the safe use of this system in living systems. Therefore, further research to activate DNAzymes, e.g., by stable cavitation using auxiliaries like microbubbles [38,39] will be necessary. Moreover, the reduction of tissue damage through cavitation effects mandates short sonication times.…”

Sonogenetics for Monitoring and Modulating Biomolecular Function by Ultrasound

“…Gas-filled microbubbles have been employed to augment the mechanical effects induced by US. [12,108] However, microbubbles exhibit a limited lifetime in vivo and a restricted capacity to cross biological barriers. [109] In contrast, a growing trend involves the utilization of microbubble-free macromolecular systems.…”

Sonogenetics for Monitoring and Modulating Biomolecular Function by Ultrasound

“…Gas‐filled microbubbles have been employed to augment the mechanical effects induced by US [12,108] . However, microbubbles exhibit a limited lifetime in vivo and a restricted capacity to cross biological barriers [109] .…”