Realizing Highly Efficient Sonodynamic Bactericidal Capability through the Phonon–Electron Coupling Effect Using Two-Dimensional Catalytic Planar Defects

Abstract

Conferring catalytic defects in sonosensitizers is of paramount importance in reinforcing sonodynamic therapy. However, the formation of such 0D defects is governed by the Schottky defect principle. Herein, 2D catalytic planar defects are designed within Ti3C2 sheets to address this challenge. These specific planar slip dislocations with abundant Ti3+ species (Ti3C2-SD(Ti3+)) can yield surface-bound O due to the effective activation of O2, thus resulting in a substantial amount of 1O2 generation and the 99.72% ± 0.03% bactericidal capability subject to ultrasound (US) stimulation. It is discovered that the 2D catalytic planar defects can intervene in electron transfer through the phonon drag effect—a coupling effect between surface electrons and US-triggered phonons—that simultaneously contributes to a dramatic decrease in O2 activation energy from 1.65 to 0.06 eV. This design has achieved a qualitative leap in which the US catalytic site has transformed from 0D to 2D. Moreover, it is revealed that the electron origin, electron transfer, and visible O2 activation pathway triggered by US can be attributed to the phonon–electron coupling effect. After coating with neutrophil membrane (NM) proteins, the NM-Ti3C2-SD(Ti3+) sheets further demonstrate a 6-log10 reduction in methicillin-resistant Staphylococcus aureus burden in the infected bony tissue.