基于层状双氢氧化物/胶束的多功能纳米诊疗剂的构建及其可视化肿瘤靶向功能研究

The design and construction of new nanotheranostics have important theoretical and practical value in the treatment of cancer. The project intends to construct a new nanocomposite through self-assemble with polymer micelles and 5-hydroxyuracil-loaded layered double hydroxides (LDHs) and prepare stable nanotheranostics under physiological conditions for efficient drug targeted delivery, controlled release and molecular imaging. The nanotheranostics are designed to covalently graft chondroitin sulfate A (CSA) with deoxycholic acid and cell-penetrating peptide (TAT) and form reducing-sensitive micelles. Efficient drug-targeted delivery of nanotheranostics are carried out with the help of CD44 receptor targeting of CSA and transmembrane capability of TAT. Making use of the properties of micelles and drug-loaded LDHs could realize reductive and pH dual-responsive controlled release of drugs. Mn2+ or Gd3+-doped LDHs could achieve magnetic resonance imaging (MRI) capacities. This research will prepare the nanocomposite material with stable and controllable size, high loading rate and MRI capacity through the adjustment and optimization of method. Then the corresponding experimental methods are used to conduct in-depth study of drug delivery, tumor targeting and imaging treatment performance of composite material. The biological safety of composite material and the effect of compounding micelles with LDHs on the stability of the material in physiological media will be evaluated and investigated. The nanotheranostics will provide new ideas and theoretical basis for modern cancer treatment.

设计和构建新型纳米诊疗剂在癌症的治疗中具有重要的理论意义和应用价值。本项目拟将聚合物胶束和负载5-氟尿嘧啶的层状双氢氧化物（LDHs）自组装形成纳米复合材料，制备生理条件下稳定的纳米诊疗剂，实现高效的药物靶向递送、可控释放和分子成像。该纳米诊疗剂的设计思路是将去氧胆酸、细胞穿膜肽（TAT）与硫酸软骨素A（CSA）共价接枝形成还原敏感性胶束，借助CSA的CD44受体靶向性和TAT的穿膜能力进行高效的药物靶向递送，利用胶束与载药LDHs的特性使药物实现还原和pH双重响应性可控释放，应用Mn2+或Gd3+掺杂的LDHs实现磁共振成像（MRI）。本项目拟通过方法的调控和优化以期获得稳定、粒径可控、较高载药率和MRI能力的纳米复合材料，利用相应的实验手段深入研究复合材料的递药、肿瘤靶向和成像治疗性能，初步评价其生物安全性，探讨胶束与LDHs复合对提高材料在生理介质中稳定性的影响，阐明其细胞摄取机制。

实现肿瘤的精准诊断和高效治疗一直是现代医学关注和追求的重要目标。构建新型纳米诊疗剂在癌症的治疗中具有重要的理论意义和应用价值。基于含Mn和Gd的纳米材料的磁共振弛豫性能，以及层状双氢氧化物（LDH）层板的可调性，课题组通过合成方法的精确调控将细胞穿膜肽（TAT）修饰的内源两亲性聚合物胶束TsCsD应用于Mn或Gd杂化载药LDHs的稳定分散和隐身，构建了2种能够同时进行MR成像以及肿瘤靶向治疗的癌症诊断治疗制剂Mn-LDH/5Fu@CsD（LM5W）和Gd-LDH/5Fu@TsCsD（LG5WT）。材料表征结果显示，我们成功制备了具有良好稳定性，合适粒径范围及较高载药率的LM5W和LG5WT纳米制剂，该制剂均具有pH依赖的体外释放行为，可以做到应激触发高效可控释放。LM5W具有pH依赖的T1加权成像效果，其弛豫率达到9mM s-1。LG5WT制剂中，5Fu的负载以及胶束的包覆都增加了其T1弛豫率，且发现其具有T1-T2双模态加权弛豫效果；通过细胞存活率 细胞死活，细胞凋亡分析证实了LM5W和LG5WT在体外能够有效抑癌。LMcy5W和LGFWT在CLSM图以及流式细胞图中细胞对Cy5-dsDNA/FITC的摄入强度说明该制剂可以被细胞有效摄取和释放。细胞MRI研究中，随着Mn/Gd浓度的升高，弛豫时间降低，加权成像图中信号变化明显，验证了LM5W在细胞层面具有良好的T1加权成像性以及LG5WT的T1-T2加权成像性。体内药效学实验中，LM5W和LG5WT组的瘤块体积和体重生长曲线随着时间增加变缓，小动物荧光成像研究中显示2种纳米制剂均能在瘤块处显著积累，动物MRI实验中，随着时间增加出现的显著加权成像信号变化也进一步证明了LM5W的良好T1加权成像性以及LG5WT的T1-T2加权成像性。这些结果都验证了LM5W和LG5WT作为一种癌症诊断治疗制剂的有效性。该项目为癌症的精准治疗提供了新思路，为LDH的临床转化应用奠定了一定的理论基础。