黑磷微泡用于脑肿瘤术后放化联合治疗的机制研究

Patient with malignant brain tumor always need to take surgery, however, it is high risk to get cancer metastasis recurrence afterwards, and therefore, adjuvant treatments of radio/chemotherapy is necessary. However, effect of radio/chemotherapy is not always help and actually with significant side effects. Imprecisely and low utilization are two key points that induce side effects. Apart from blood brain barrier (BBB), poor targeting and efflux pumps on cancer cells are the other two main culprits. Low drug accumulation in cancer leads to organ toxicity. This is mainly due to poor targeting and/ or multidrug resistance effect (MDR) of cell. Can we explore a drug delivery system, which can satisfy simultaneously BBB penetration as well as cancer cell accumulation, but have MDR inhibition property? In order to answer this question, we design to establish a multi-functionalized micro-/nano bubbles (MNBs) with black phosphorus nanodots (BPNDs) encapsulated. BP is a rising star in two-dimensional materials field of drug delivery. It is well-known that BP has high specific surface area for drug loading, and trigger-able degradation properties as sonosenstizer. Herein, we adsorb radiopharmaceutical 99mTcN-NOET on BP surface, making it a mobile irradiation ‘bomb’, and further encapsulates it with lipidated microbubbles. Thanks to microbubbles cavitation effect, 99mTcN-NOET-BP enter cytosol via sonoporation. Thereafter, BP accumulates on edge of inner layer cytomembrane, playing a role as ‘inhibitor’, blocking efflux pumps from inner side of cytomembrane, leading to the effect of anti-multidrug resistance (MDR). Besides, as a sonosenstizer, its deposition can be triggered via focused ultrasound (FUS). The degradation process releases reactive oxygen species (ROS) which leads to biomacromolecules structures diassociation and finally induces cancer cell apoptosisis. The process is so-called cancer sonodynamic therapy. In order to deliver BP nanodots (BPNDs) specifically into brain tumor, we introduce a pair of artificial receptor (Coil-K) and ligand (Coil-E) for target modification. Once Coil-K and Coil-E are mixed in aqueous, they will immidiately form coiled coil motif CC-K/E, and release >11.5 kcal/ mol binding energy, which is strong enough to conquer energy barriers and finally achieve with fusion. We decorate Coil-K on surface of lipid membrane via self-assembly with 99mTcN-NOET-BP encapsulated in lipid layers of MNBs. Oscilliation ultrasound wave leads to cavitiation of MNBs and trigger bubble targeted exploration cargo release in situ. Coil-K release in cancer cell and anchor on cytomembrane under irridiation of ultrasound and cytomembrane phospholipid self-assembly, it can stably expresses on cytomembrane for about 1 week. Meanwhile, paclitaxel (PTX) is encapsulated in Coil-E decorated liposome in 1mol% 1mM concentration, yielding PTX-LE. Once coiled coil motif CC-K/E formed, binding energy release will lead to membrane fusion with PTX release in cytosol. With BP blocking efflux pumps in a piston way, both 99mTcN-NOET and PTX are encapsulated in cancer cell, leading to early apoptosis of cancer cell. Finally, sonodynamic therapy of BP is triggered with FUS and lead to late apoptosis of cancer cell. The project creatively combines target drug delivery system investigation with anti-multidrug resistance study, lightening up a multifunctionalized cancer therapy protocols with black phosphorus microbubbles.

恶性脑肿瘤多呈浸润生长，手术切除辅以放射线及化学治疗，预后都较差。已经公认的原因一是放射辐照区精准度不够使正常脑组织受累，二是血脑屏障（BBB）阻碍大部分化学药物的透过，且肿瘤耐药性外排导致药物失效。近期的研究发现黑磷是可降解声敏剂，具有高载药率及形态可控的特点。基于前期研究基础，该项目拟构建可降解的黑鳞微泡药物载体，利用聚焦超声（FUS）介导载药黑磷微泡解决BBB屏障及多药耐药（MDR）的难题。构建修饰人工受体K的99mTc标记黑磷微纳米泡，注入体循环，用聚焦超声辐照靶标，微泡爆破，瞬时开放声孔同时释药，使人工受体K静电吸附于细胞膜上。再由修饰人工配体E的载紫杉醇脂质体通过K/E特异性结合由膜融合途径释放药物。胞液内黑磷模拟活塞封堵蛋白外排转运通道，延长药物循环。最后通过聚焦超声激活黑磷声敏剂，释放活性氧引发自降解，同时诱导靶细胞凋亡，达到靶向精准并载体抗MDR的目的。

脑胶质瘤作为发病率最高的中枢神经系统肿瘤其临床治疗收益不高，缺乏高效的脑肿瘤靶向给药方式，本研究受启发于神经元递质释的SNARE假说（SNARE蛋白复合体形成过程释放能量帮助细胞膜与递质囊泡发生膜融合，完成递质的释放）设计了多肽K与多肽E，分别作为人工受体和人工配体，先用超声将人工受体多肽K引入到脑胶质瘤部位，然后多肽E修饰的载阿霉素（DOX）脂质体经静脉注射，通过多肽K与多肽E的特异性结合释放能量介导脂质体与细胞膜融合释放药物，实现药物的可控、靶向、高效递送。.