We report the design, synthesis, characterization and in vitro testing of a novel nanodrug based on a covalent linking model that allows intracellular controlled release of the pharmaceutical payload. A new synthetic strategy is implemented by direct coupling of as-synthesized (pyridin-2-yldisulfanyl)alkyl carbonate derivatives of camptothecin (CPT) with thiol groups of silica hybrid nanoparticles containing a non-porous core and a mesoporous shell. Upon reaction with thiols in physiological conditions, disulfide bridge cleavage occurs, releasing the naked drug after an intramolecular cyclization mechanism. Additional incorporation of a fluorophore into particles core facilitates imaging at the subcellular level for the monitoring of uptake and delivery. Confocal microscopy experiments in HeLa cervix cancer cells confirms that nanoparticles enter the cells by endocytosis but are able to escape from endo-lysosomes and enter the cytosolic compartment to release their cargo. The incorporation to cells of L-buthionine-sulfoximine, a glutathione inhibitor allows concluding that the intracellular releasing mechanism is mainly driven by the reducing activity of this tripeptide. This camptothecin nanoplatform shows the same cytotoxic activity than the free drug and is clearly superior to those release systems depending on enzymatic hydrolysis (as determined by calculation of the IC50 ratios).
我们报道了一种基于共价连接模式的纳米药物的设计、合成、表征及体外测试,该模式允许药物在细胞内受控释放。通过直接将合成的(
吡啶-2-二
硫基)烷基
碳酸酯类喜树碱(C
PT)衍
生物与含非多孔核心和介孔壳层的
硅基杂化纳米粒子的
硫醇基团耦合,实现了新的合成策略。在生理条件下与
硫醇反应时,二
硫键断裂,通过分子内环化机制释放裸药。在粒子核心中额外引入荧光团有利于亚细胞
水平成像,以便监测摄取和递送。在HeLa宫颈癌细胞中进行的共聚焦显微镜实验证实,纳米粒子通过内吞作用进入细胞,但能够逃逸出内溶酶体,进入胞质溶胶释放其内含物。向细胞中加入
谷胱甘肽抑制剂L-
丁硫氨酸亚砜
亚胺,可以得出结论,细胞内释放机制主要由该三肽的还原活性驱动。这种
喜树碱纳米平台显示出与自由药物相同的细胞毒性活性,并且在依赖酶解释放的系统中明显优越(通过计算IC50比值确定)。