An efficient radiotherapeutic agent is synthesized using ultrathin two-dimensional 30-nm-wide and 2-nm-thick Bi₂Se₃ nanosheets (NSs) as a radiosensitizer. Chitosan (CS) and RGD peptide are employed to enhance the radiotherapy efficiency and biocompatibility. The Bi₂Se₃-CS-RGD NSs exhibit excellent targeting ability to αvβ3 integrin-overexpressing cancer cells and potent radiosensitization efficiency with high stability. Detailed in vitro experiments show that the Bi₂Se₃-CS-RGD NSs enhance the sensitivity of HeLa cells to X-ray-induced cell death by inhibiting TrxR activities and activating downstream reactive oxygen species-mediated signaling pathways. In vivo experiments using intravenous or intratumor injection demonstrate that the Bi₂Se₃-CS-RGD NSs are more efficient tumor growth inhibitors compared to bare Bi₂Se₃ NSs. The multifunctionality of the NSs enables the use of photoacoustic imaging and magnetic resonance imaging to examine their targeting ability and therapeutic effects, respectively. In addition, the RGD-decorated Bi₂Se₃ NSs show much better in vivo biocompatibility and can be efficiently expelled from the body after 48 h post injection. This study reveals an effective and safe theranostic agent for next-generation cancer radiotherapy.

使用超薄的二维30 nm宽和2 nm厚的Bi ₂ Se ₃纳米片（NSs）作为放射增敏剂，可以合成一种有效的放射治疗剂。壳聚糖（CS）和RGD肽用于增强放射治疗效率和生物相容性。Bi ₂ Se ₃ -CS-RGD NSs对过表达αvβ3整联蛋白的癌细胞具有出色的靶向能力，并且具有高稳定性和有效的放射增敏效率。详细的体外实验表明，Bi ₂ Se ₃ -CS-RGD NSs通过抑制TrxR活性和激活下游活性氧介导的信号通路，增强了HeLa细胞对X射线诱导的细胞死亡的敏感性。使用静脉内或肿瘤内注射的体内实验表明，与裸Bi ₂ Se ₃ NS相比，Bi ₂ Se ₃ -CS-RGD NSs是更有效的肿瘤生长抑制剂。NS的多功能性使得能够使用光声成像和磁共振成像来分别检查其靶向能力和治疗效果。此外，RGD修饰的Bi ₂ Se ₃ NSs在体内具有更好的生物相容性，注射后48 h可以有效地从体内排出。这项研究揭示了一种用于下一代癌症放射治疗的安全有效的治疗治疗剂。