Modulating a Massive Set of Biomolecular Structures by Sono-Mechanical Force

Mechanical modulation of biomolecular structures by single-molecule techniques, such as optical tweezers, has revealed subtle conformational dynamics and enabled precise modulation of functional properties. However, such tools are limited to manipulating one or a few molecules at a time in extracellular settings, posing significant challenges for scaling force-based methods to achieve high sensitivity and efficacy both outside and within cells. Here, low-power (<5.3 mW cm^-2) ultrasound is employed to generate sono-mechanical forces without formation of sonodynamic radicals, which are known to irreversibly alter molecular structures. By calibrating against optical-tweezers-based single-molecule force spectroscopy, this study quantifies for the first time that at least 29 pN sono-mechanical force can be generated at 5.3 mW cm^-2 sonication power, capable of simultaneously and reversibly unfold an ensemble set of DNA structures, including G-quadruplexes and hairpins. Notably, the same sono-mechanical unfolding is observed in cells, where intercalated doxorubicin ligands are released from unfolded DNA hairpin carriers, resulting in targeted cancer cell death. These findings show ultrasound can simultaneously manipulate a large population of biomolecules without requiring fixed orientations, offering a flexible and nonintrusive force generation to reversibly unfold molecular structures. This platform holds profound potential for applications in molecular biophysics, smart materials, and precision medicines.