Biodegradable Bi2O2Se Quantum Dots for Photoacoustic Imaging‐Guided Cancer Photothermal Therapy

Abstract As new 2D layered nanomaterials, Bi 2 O 2 Se nanoplates have unique semiconducting properties that can benefit biomedical applications. Herein, a facile top‐down approach for the synthesis of Bi 2 O 2 Se quantum dots (QDs) in a solution is described. The Bi 2 O 2 Se QDs with a size of 3.8 nm and thickness of 1.9 nm exhibit a high photothermal conversion coefficient of 35.7% and good photothermal stability. In vitro and in vivo assessments demonstrate that the Bi 2 O 2 Se QDs possess excellent photoacoustic (PA) performance and photothermal therapy (PTT) efficiency. After systemic administration, the Bi 2 O 2 Se QDs accumulate passively in tumors enabling efficient PA imaging of the entire tumors to facilitate imaging‐guided PTT without obvious toxicity. Furthermore, the Bi 2 O 2 Se QDs which exhibit degradability in aqueous media not only have sufficient stability during in vivo circulation to perform the designed therapeutic functions, but also can be discharged harmlessly from the body afterward. The results reveal the great potential of Bi 2 O 2 Se QDs as a biodegradable multifunctional agent in medical applications.