Ultrasound-based mechanochemical generation of reactive oxygen species from nanoparticle-conjugated amyloid fibrils†

Piezoelectric biomaterials have diverse potential biomedical applications via ultrasound-based wireless mechanochemical reaction at a remote area of the body/medical device. However, most biomaterials have weak piezoelectric properties compared to chemically designed piezoelectric materials. In the current approach, piezoelectric properties of certain biomaterials are enhanced by transforming them into anisotropic fibril/sheet-like morphology. Here, we demonstrate that the piezoelectric property of amyloid fibrils can be enhanced by 2 times via conjugation with nanoparticles and this can enhance the ultrasound-based mechanochemical production of reactive oxygen species by 4 times. In particular, we have synthesized nanoparticle-conjugated lysozyme fibrils with a piezoelectric constant value as high as 82 pm V⁻¹. Thin films derived from these materials can generate periodic voltage/current pulses under the exposure of medical-grade ultrasound that can reach up to 1 V/15 nA. A colloidal dispersion of these materials generates superoxide/hydroxyl radicals via ultrasound-based mechanochemical reaction and degrade a dye. This strategy can be adapted to improve the mechanochemical reaction performance of weakly piezoelectric materials.