Engineering defected 2D Pd/H-TiO2 nanosonosensitizers for hypoxia alleviation and enhanced sono-chemodynamic cancer nanotherapy

Abstract

Background: Sonodynamic therapy (SDT) is a burgeoning modality for cancer therapy owing to its high tissue-penetrating capability, controllability and safety. Whereas, the undesirable reactive oxygen species (ROS) yield of sonosensitizers and tumor hypoxia are two vulnerable spots of SDT. Therefore, it is an advisable strategy to augment ROS level and simultaneously relieve hypoxia for SDT to arrive its full potential in cancer treatment.

Results: In this work, the defected two-dimensional (2D) Pd/H-TiO₂ nanosheets (NSs) with triple antineoplastic properties were dexterously elaborated and engineered using a facile one-pot Pd-catalyzed hydrogenation tactic by loading a tiny amount of Pd and then inletting hydrogen flow at atmospheric pressure and temperature. The 2D black Pd/H-TiO₂ NSs with oxygen defects exerted eximious SDT effect based on the decreased bandgap that made it easier for the separation of electrons and holes when triggered by ultrasound as theoretically guided by density functional theory calculations. Additionally, Pd/H-TiO₂ NSs could serve as Fenton-like agents because of the presence of oxygen defects, facilitating the conversion of hydrogen peroxide into hydroxyl radicals for exerting the chemodynamic therapy (CDT). Simultaneously, the introduced tiny Pd component possessed catalase-like activity responsible for oxygen production to ameliorate hypoxic condition and thus contributed to improving SDT and CDT efficacies. Both in vitro and in vivo results provided compelling evidences of high ROS yield and aggrandized sono-chemodynamic effect of Pd/H-TiO₂ nanosonosensitizers with the detailed underlying mechanism investigation by RNA sequencing.

Conclusion: This work delves the profound potential of Pd-catalyzed hydrogenated TiO₂ on oncotherapy, and the effective antineoplastic performance and ignorable therapeutic toxicity make it a powerful competitor among a cornucopia of nanosonosensitizers.

Keywords: Chemodynamic therapy; Nanozyme; Oxygen deficiency; Pd/H-TiO2 nanosheets; Sonodynamic therapy.