【作者】 李萌；

【导师】 刘轶；

【作者基本信息】 吉林大学 ， 物理化学， 2023， 硕士

【摘要】 随着辐射技术的迅速发展,电离辐射被广泛应用于工业和医学等多种领域。然而,高能电离辐射可以通过破坏DNA和产生活性氧的方式对健康组织造成重大损害,并导致癌症、身体畸形,甚至死亡。目前所开发的用于辐射防护的药物都存在副作用强、毒性高、半衰期短等缺点,还没有一种实用的辐射防护剂用于临床常规应用。因此,设计高效的、低毒性的辐射防护剂用于满足癌症放射治疗日益增长的需要,是目前急需解决的问题。近年来,纳米载体为克服药物分子溶解度低、毒副作用强、稳定性不足等缺点提供了机会。迄今为止,已经报道了许多基于纳米载体的辐射防护药物递送系统,包括有机聚合物纳米载体、无机聚合物纳米载体和分子药物自组装的纳米级辐射防护剂。白藜芦醇是一种天然多酚,主要存在于水果、坚果、葡萄和红酒中。据报道其药理作用包括抗凋亡、抗炎症和抗癌,且白藜芦醇已被证实具备清除自由基的作用,可以保护正常组织细胞免受辐射诱导的损伤。但白藜芦醇水溶性差,体内生物利用度低,代谢率高,严重限制了其生物学应用。基于此背景,我们设计制备了具有自由基清除活性的白藜芦醇聚合物微球作为辐射防护剂,并研究了白藜芦醇聚合物微球在电离辐射防护领域的应用。在第二章中,我们分别利用两种方法制备了白藜芦醇聚合物微球。通过对两种制备方法进行对比,我们选择了利用白藜芦醇与氨基酸通过Mannich缩合制备聚合物微球的方法,并对产物白藜芦醇聚合物微球的理化性质进行了详细的表征,考察其作为辐射防护剂的潜力。研究表明,白藜芦醇聚合物微球分子间作用力主要以π-π相互作用为主,平均尺寸为138 nm,胶体稳定性好,且能够有效清除DPPH和ABTS自由基。该聚合物微球细胞毒性低,能够有效被人脐静脉内皮细胞HUVEC摄取。在第三章中,我们首先通过体外实验考察了白藜芦醇聚合物微球的辐射防护能力。我们测试了X-ray照射前后细胞毒性、细胞内ROS水平、DNA损伤、线粒体膜电位、GSH水平、细胞色素C、Caspase-3、BAX、BCL₂蛋白表达等,实验结果表明该聚合物微球具有较强的体外辐射防护能力。体内实验结果也证明白藜芦醇聚合物微球生物相容性好,可作为自由基清除剂有效清除X-ray辐射产生的ROS自由基,提高小鼠体内超氧化物歧化酶SOD水平、降低ROS有害副产物MDA水平,减轻DNA损伤,恢复BMNC数量,保护细胞增殖能力,维持肠道组织的正常结构,提高辐照小鼠存活率。综上所述,我们设计的白藜芦醇聚合物微球在体外和体内实验中均表现出优异的辐射防护能力,是一种有潜力的辐射防护剂。更多还原

【Abstract】 Radioisotopes and radiation technology is developing rapidly,ionizing radiation is widely used in various fileds such as industry and medicine.However,high-energy radiation can also cause significant damages in healthy tissues via damaging DNA and producing reactive oxygen species（ROS）and induce cancer,physical deformity even death.However,the existing radioprotective agent has serious side effects,high toxicity and short half-life.There is no practical radioprotective agent for routine clinical application.Therefore,it is urgent to design highly effective radioprotectants with low toxicities that can satisfy the increasing demands of cancer radiation therapy.In recent years,nanocarriers have provided opportunities to overcome the shortcomings of low solubility,side effects and lack of stability.Currently,many nanocarrier-based drug delivery systems for radiation protection have been reported which encompass organic polymer nanocarriers,inorganic nanocarriers,as well as nanosize radioprotectors assembled by molecular radioprotective drugs.Resveratrol,a polyphenolic compound primarily found in grapes,nuts,fruits,and red wine.Its pharmacological effects have been reported to include antioxidant,anti-inflammatory,anticancer.Resveratrol has been confirmed to have free radical scavenging effects that protect normal tissue cells from radiation-induced damage.However,resveratrol presenting some disadvantages such as low chemical stability,hydrophobicity,low bioavailability and a high metabolization rate in vivo which limits its biological application severely.In this context,we designed and prepared resveratrol-based polymer microsphere with free radical scavenging activity as radioprotectants and explored their application in the filed of ionizing radiation protection.In chapter 2,we prepared resveratrol-based polymer microsphere by two methods.By comparing the two preparation methods,we chose the method to prepare polymer microsphere by condensation of resveratrol and amino acid by Mannich,and the physicochemical properties of the polymer microsphere were characterized in detail to investigate the potential as radioprotective agent.Resveratrol molecules assemble to form polymer microsphere through non-covalent interactions such asπ-πinteractions assemblies.The average diameter of the polymer microsphere is 138 nm,which has good stability and can effectively scavenging DPPH and ABTS free radicals.The polymer microsphere has low cytotoxicity and could be efficiently taken up by HUVEC cells.In chapter 3,we researched the radiation protection ability of polymer microsphere by in vitro experiments.We tested the cytotoxicity,intracellular ROS level,DNA damage,mitochondrial membrane potential,GSH level,cytochrome C,Caspase-3,BAX,BCL₂ protein expression before and after X-ray irradiation,and the experimental results showed that the nanomaterials had excellent radiation protection ability.The in vivo experimental results show that the polymer microsphere has good biocompatibility and can be used as free radical scavenger to effectively get rid of the ROS free radicals generated by X-ray,improve the level of superoxide dismutase SOD and reduce the level of ROS harmful by-product MDA,decrease the radiation-induced DNA damages,recover the radiation-decreased BMNC,protect the proliferation ability of cells,maintain the normal structure of intestinal tissue and improve the overall survival rate of irradiated mice.In summary,it was found that the resveratrol-based polymer microsphere showed excellent radiation protection ability in both in vivo and in vitro experiments and is a potential radioprotectant.更多还原