Ultrasound-driven mechanophore activation in living plants

Abstract

This study presents a biocompatible, ultrasound-responsive platform for remotely activating mechanochemical reactions within live plant tissue. Fluorogenic Mechanophore-embedded silica NanoParticles (FMNPs) that are thermally stable were engineered to emit blue fluorescence at 440 nm upon mechanical activation. In Solanum lycopersicum (tomato) leaves, activation was achieved through the synergistic combination of gas vesicles (GVs) and high-frequency focused ultrasound (FUS, 550 kHz), enabling spatially localized and minimally invasive stimulation. Low-frequency ultrasound (25 kHz) triggered activation but caused extensive tissue damage, while high-frequency FUS alone was biocompatible yet insufficient to activate FMNPs. Incorporation of GVs as a cavitation amplifier significantly boosted activation efficiency under mild acoustic conditions without observable tissue disruption. In planta fluorescence imaging confirmed that FMNPs retained their functionality after injection into leaf vasculature, and only the combination of GV and FUS produced a statistically significant fluorescence increase, indicating successful mechanochemical activation. This represents a demonstration of noninvasive and biocompatible ultrasound-induced mechanophore activation in live plants. This modular and noninvasive strategy opens possibilities for programmable release of regulatory and metabolic chemicals, biosensing, and synthetic molecular control in plant systems.