活性氧物种是含氧的高化学活性物质，是细胞正常生物化学反应的副产物，也是细胞发生氧化损伤的直接原因。水的辐解也会产生羟基自由基等活性氧物种，这些活性氧物种会在肿瘤放射治疗中杀伤癌细胞。同时，水的辐解过程会生成水合电子，具有较强的还原性，可以还原一些有机基团。长期以来，大量的工作研究了相当多的小分子体系，制备了相当多种响应性各异的响应性药物。但是，由于在水的辐解过程中，产生的活性物种较少，而此类小分子体系常常是一个分子需要同一个或者多个活性物种发生作用，才能引发相应响应。因而，这些体系的灵敏度仍有提高空间，且对原始底物的结构都有所限制。而同小分子体系不同的是，自降解高分子作为一类在特定刺激下能够自发降解为单体的高分子化合物，能够在响应后发生解聚。这种体系内发生的自发解聚反应会显著影响其自组装体的结构，因而具有潜在的高灵敏度响应的结构基础。过去的研究显示3，5-二羟基苯甲醇结构能够有效地同水的辐解反应中产生的羟基自由基结合，而（4-（（4-乙酰基苄基）二甲基氨基）苯基）甲醇负离子可以同水的辐解中生成的水合电子结合，这两者发生响应后，可以生成醌式结构的产物，这一过程存在引发聚氨酯类自降解高分子自发降解的潜力。这里，基于已报道的活性氧响应性或水合电子响应性体系，我们设计了一类能够对活性氧或水合电子具有一定响应性的自降解高分子，并且通过引入聚乙二醇链制成纳米微胶囊，可以利用水的辐解过程产生的活性氧或水合电子，作为体内定向药物投送的载体，用于肿瘤等疾病的治疗中，具有较现有阶段类似体系更加高的灵敏度。本论文开发的高分子对水的辐解产生的羟基自由基或水合电子具有响应性，有望实现一些药物的高灵敏的定向投送，能够对癌症等疾病的治疗，具有一定的理论和实践意义。

Reactive oxygen species (ROS) are the highly reactive metabolic byproduct of living cells. ROS can also be generated by the radiolysis of water, such as hydroxyl radical , and hydrated electrons.ROS are important for tumor cytotoxicity in Radiotherapy. As the low concentration of the ROS and hydrated electrons formed in radiolysis, many previous responsive systems are designed as small molecules. However, these small molecule systems typically respond to one or more active species to generate one activated product, hence limited sensitivity. Most reactive oxygen responsive or hydrated electron response systems still have some room for improvement in sensitivity and are somewhat restrictive in terms of substrate structure. We hypothesize that selfimmolative
polymers which can react with ROS can offer a new route to design response systems which can introduce a significant change in the structure of the whole system through spontaneous depolymerization triggered by a small activation event. Herein, we show that 3,5-dihydroxy benzyl alcohol is a highly responsive trigger of self-immolative polymer poly (4-amino benzyloxy)carbamate) which can react with hydroxy radical distinctively. (4-((4-acetylbenzyl)dimethylammonio)phenyl)methanolate, which was found to have good ability to react with hydrated electrons, can also work as a trigger for the spontaneous depolymerization of poly ((4-amino benzyloxy)carbamate). After covalently connecting poly ((4-amino benzyloxy)carbamate) chain with hydrophilic mPEG, amphiphilic block copolymer were prepared.The block copolymer could self-assemble under aqueous condition to form nano-capsules, which can further encapsulate a wide range of drugs and display high sensitivity to hydroxyl radicals or reactive oxygen species. Overall, these polymers have a potential to work as a radiotherapy induced drug delivery system in multidisciplinary treatment of malignancy.