Piezo-Activated Atomic-Thin Molybdenum Disulfide/MXene Nanoenzyme for Integrated and Efficient Tumor Therapy via Ultrasound-Triggered Schottky Electric Field.

Monolayer molybdenum disulfide (MoS 2 ) nanoenzymes exhibit a piezoelectric polarization, which generates reactive oxygen species to inactivate tumors under ultrasonic strain. However, its therapeutic efficiency is far away from satisfactory, due to stackable MoS 2 , quenching of piezo-generated charges, and monotherapy. Herein, chitosan-exfoliated monolayer MoS 2 (Ch-MS) is composited with atomic-thin MXene, Ti 3 C 2 (TC), to self-assemble a multimodal nanoplatform, Ti 3 C 2 -Chitosan-MoS 2 (TC@Ch-MS), for tumor inactivation. TC@Ch-MS not only inherits piezoelectricity from monolayer MoS 2 , but also maintains remarkable stability. Intrinsic metallic MXene combines with MoS 2 to construct an interfacial Schottky heterojunction, facilitating the separation of electron-hole pairs and endowing TC@Ch-MS increase-sensitivity magnetic resonance imaging responding. Schottky interface also leads to peroxidase mimetics with excellent catalytic performance toward H 2 O 2 in the tumor microenvironment under mechanical vibration. TC@Ch-MS possesses the superior photothermal conversion efficiency than pristine TC under near-infrared ray illumination, attributed to its enhanced interlaminar conductivity. Meanwhile, TC@Ch-MS realizes optimized efficiency on tumor apoptosis with immunotherapy. Therefore, TC@Ch-MS achieves an integrated diagnosis and multimodal treatment nanoplatform, whereas the toxicity to normal tissue cells is negligible. This work may shed fresh light on optimizing the piezoelectric materials in biological applications, and also give prominence to the significance of intrinsic metallicity in MXene.