Yadong Liu,1,2,* Huiyan Lv,3,* Yaodong Chen,4,* Shazhou Ye,1 Zhong Zheng,1 Lei Chen,1 Zejun Yan,1 Xingyi Li5 

1Department of Urology, The First Affiliated Hospital of Ningbo University, Ningbo, Zhejiang, People’s Republic of China; 2State Key Laboratory of Ultrasound in Medicine and Engineering, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China; 3Department of Nephrology, the First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, People’s Republic of China; 4Department of Ultrasonic Imaging, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, People’s Republic of China; 5Department of Ultrasonic Imaging, The First Affiliated Hospital of Ningbo University, Ningbo, Zhejiang, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Xingyi Li, Email fyylixingyi@nbu.edu.cn Zejun Yan, Email fyyyanzejun@nbu.edu.cn

Background: Due to the complex structure and variable microenvironment in the progression of bladder cancer, the efficacy of traditional treatment methods such as surgery and chemotherapy is limited. Tumor residual, recurrence and metastasis are still difficult to treat. The integration of diagnosis and treatment based on nanoparticles can offer the potential for precise tumor localization and real-time therapeutic monitoring. Photodynamic therapy (PDT), which generates reactive oxygen species (ROS) under laser irradiation, can be effectively combined with photothermal therapy (PTT) and chemodynamic therapy (CDT) to target non-muscle-invasive bladder tumors. In this study, Cu2(OH)PO4@PAA nanoparticles with photoacoustic (PA) imaging capabilities were utilized to explore their potential for precise intraoperative tumor identification and multimodal therapy.
Methods: The generation of ROS was detected to evaluate the potential of PDT and copper ion-induced CDT. Additionally, the PA imaging capability and biosafety of the nanoparticles were systematically evaluated. Finally, the anti-tumor efficacy of Cu2(OH)PO4@PAA-mediated CDT/PDT/PTT and the underlying mechanisms were assessed in vitro and in vivo.
Results: Cu2(OH)PO4@PAA could implement the CDT effect through a Cu+-induced Fenton-like reaction and substantial consumption of glutathione (GSH). Besides, Cu2(OH)PO4@PAA could execute NIR-I-triggered PDT by generating 1O2 and thermal images showed that Cu2(OH)PO4@PAA has the potential to perform PTT through light-heat energy conversion. Cu2(OH)PO4@PAA possessed dose-dependent PA signal transduction ability. Without laser exposure, Cu2(OH)PO4@PAA weakened cell viability, induced apoptosis, and suppressed epithelial-mesenchymal transition (EMT) by exhibiting the CDT effect alone. However, after the introduction of PDT and/or PTT, the above anti-tumor effects were significantly enhanced.
Conclusion: This study systematically explores the combined anti-cancer mechanisms from the perspective of epithelial-mesenchymal transition, providing a theoretical and technical foundation for bladder cancer treatment.

Keywords: Cu2(OH)PO4@PAA, chemodynamic therapy, photodynamic therapy, photothermal therapy, bladder cancer