Data underlying the publication: Reaction network analysis of organochloride mediated oxidation induced by ionizing radiation

The generation of organoperoxy radical by irradiating aqueous solutions of organochlorides depends on the concentration of organochloride, where low concentration of organochloride results in low yield of peroxyl radical. The need of high concentration of organochloride limits the application in cancer therapy as most small molecule organochlorides show liver toxicity at elevated concentrations. To study if the oxidation is feasible at low concentration of organochloride, we proposed a reaction network where the effect of molecular oxygen is included. We hypothesized that oxygen competes with the organochloride to react with aqueous electrons, thereby causing a low yield of peroxyl radical at low organochloride concentrations. However, oxygen is necessary in the peroxyl radical formation pathway, which complicates straightforward prediction of reaction outcome. We developed a mathematic model to simulate the yield of peroxyl radical depending on organochloride and oxygen concentrations. The simulated results indicate that at low organochloride concentration, decreasing oxygen concentration leads to higher yield of peroxyl radical, with a peak at approximately 2% partial pressure of oxygen, and oxygen lower than 2% results in a sharp yield drop of peroxyl radical. Experiments using a thioether as reductant to quantify the peroxyl radical formation show good agreement with simulated data, verifying the proposed network. After irradiation in phosphate buffer saline/organochloride, a thioether caged dye showed a higher uncaging yield than the group without organochloride, demonstrating the viability of using thioether as a radiation sensitive group.

通过辐照有机氯（organochloride）水溶液生成有机过氧自由基（organoperoxy radical）的过程，取决于有机氯的浓度：当有机氯浓度较低时，过氧自由基的产率也偏低。高浓度有机氯的需求限制了该方法在癌症治疗中的应用，因为多数小分子有机氯在浓度升高时会表现出肝毒性。为探究低有机氯浓度下该氧化过程是否可行，我们构建了一个包含分子氧作用的反应网络（reaction network）。我们提出假说：氧会与有机氯竞争与水合电子（aqueous electrons）发生反应，进而在低有机氯浓度下导致过氧自由基产率降低。然而，氧同时也是过氧自由基生成路径中不可或缺的组分，这使得反应结果的直接预测变得复杂。我们开发了数学模型以模拟过氧自由基产率随有机氯及氧浓度的变化规律。模拟结果表明，在低有机氯浓度下，降低氧浓度可提升过氧自由基的产率，且产率在氧分压约2%时达到峰值；当氧分压低于2%时，过氧自由基产率会急剧下降。以硫醚（thioether）作为还原剂定量检测过氧自由基生成的实验结果，与模拟数据吻合良好，验证了我们提出的反应网络。在磷酸盐缓冲生理盐水（phosphate buffer saline）/有机氯体系中经辐照后，硫醚笼状染料的脱笼产率（uncaging yield）高于不含有机氯的对照组，证明了使用硫醚作为辐射敏感基团的可行性。