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

Abstract

<p>Conferring catalytic defects in sonosensitizers is of paramount importance in reinforcing sonodynamic therapy. However, the formation of such zero-dimensional (0D) defects is governed by the Schottky defect principle. We herein design two-dimensional (2D) catalytic planar defects 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 ¹O₂generation and the 99.72% ± 0.03% bactericidal capability subject to ultrasound (US) stimulation. We discover that the 2D catalytic planar defects can intervene 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. Our design has achieved a qualitative leap in which the US catalytic site has transformed from 0D to 2D. Moreover, we reveal that the electron origin, electron transfer, and visible O₂ activation pathway triggered by US can be attributed to the phonon–electron coupling effect. After coated with neutrophil membrane (NM) proteins, the NM-Ti₃C₂-SD(Ti³⁺) sheets further demonstrate a 6-log₁₀ reduction in methicillin-resistant <em>Staphylococcus aureus</em> burden in the infected bony tissue.</p>