Polyacrylic acid-modified titanium peroxide nanoparticles (PAA-TiO_x NPs) are promising radiosensitizers that enhance the therapeutic effect of X-ray irradiation after local injection into tumors. However, the mechanism for this reaction has remained unclear with the exception of the involvement of hydrogen peroxide (H₂O₂), which is released by PAA-TiO_x NPs to a liquid phase during dispersion. In the present study, a clonogenic assay was used to compare PAA-TiO_x NPs with free H₂O₂ molecules to investigate the effect exerted on the radiosensitivity of cancer cells in vitro. A cell-free dialysis method revealed that a portion of the H₂O₂ adsorbed onto the PAA-TiO_x NPs during synthesis could be released during a treatment regimen. The H₂O₂ release lasted for 7 h, which was sufficient for one radiation treatment procedure. For in vitro experiments, cultured human pancreatic cancer cells took up PAA-TiO_x NPs in 10 min after administration. Interestingly, when the cells were washed with a buffer after treatment with either a PAA-TiO_x NP or H₂O₂ solution, the intracellular H₂O₂ levels remained higher with PAA-TiO_x NP treatment compared with the H₂O₂ solution treatment. Furthermore, the effects of subsequent X-ray irradiation corresponded to the intracellular H₂O₂ levels. These results indicate that PAA-TiO_x NPs are efficient carriers of H₂O₂ into cancer cells and thus enhance the radiosensitivity.

聚丙烯酸改性的过氧化钛纳米粒子（PAA-TiO _x NPs）是有前途的放射增敏剂，可在局部注入肿瘤后增强X射线辐射的治疗效果。然而，除了过氧化氢（H ₂ O ₂）的参与外，该反应的机理还不清楚，过氧化氢由PAA-TiO _x NPs在分散过程中释放到液相中。在本研究中，采用克隆形成试验将PAA-TiO _x NPs与游离H ₂ O ₂分子进行比较，以研究其对体外癌细胞放射敏感性的影响。无细胞透析方法显示一部分H在合成过程中，吸附在PAA-TiO _x NP上的₂ O ₂可以在治疗方案中释放。H ₂ O ₂释放持续了7小时，足以进行一种放射治疗程序。对于体外实验，培养的人类胰腺癌细胞在给药后10分钟内吸收了PAA-TiO _x NP。有趣的是，当用PAA-TiO _x NP或H ₂ O ₂溶液处理后用缓冲液洗涤细胞时，与H相比，PAA-TiO _x NP处理的细胞内H ₂ O ₂含量仍然较高。₂ O ₂溶液处理。此外，随后的X射线照射的效果对应于细胞内H ₂ O _2的水平。这些结果表明PAA-TiO _x NP是H ₂ O ₂进入癌细胞的有效载体，因此增强了放射敏感性。