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为了探讨H7K(R2)2修饰的pH敏感脂质体对U87-MG细胞的靶向作用,本文选择香豆素-6(coumarin-6)为荧光探针构建了包载香豆素--6的H7K(R2)2修饰的pH敏感脂质体(coumarin--6--PSL--H7K(R2)2)。采用流式实验分别对H7K(R2)2在coumarin--6--PSL--H7K(R2)2中的比例以及coumarin-6--PSL--H7K(R2)2在U87--MG细胞的摄取途径进行研究。采用CD技术对H7K(R2)2在pH 7.4和pH 6.8条件下的二级结构进行考察。实验结果显示,H7K(R2)2在coumarin--6--PSL--H7K(R2)2中占2.5%时,其靶向作用优于1%和3.5%。细胞摄取途径实验表明,coumarin--6--PSL--H7K(R2)2进入U87--MG细胞不受菲律平、甲基--β--CD和氯丙嗪等抑制剂的影响。H7K(R2)2在pH 6.8时的二级结构多为β--turn。本研究结果表明,在H7K(R2)2修饰的pH敏感脂质体中,H7K(R2)2的最佳比例可确定为2.5%。H7K(R2)2修饰的pH敏感脂质体进入肿瘤细胞的途径主要通过低pH条件下H7K(R2)2所产生的穿膜肽样作用。H7K(R2)2在pH 6.8条件下所出现的发卡样二级结构是其产生靶向和穿透作用的可能机制。
In order to investigate the targeting effect of H7K (R2) 2-modified pH-sensitive liposomes on U87-MG cells, coumarin-6 was used as a fluorescent probe to construct a sandwich- Of H7K (R2) 2 modified pH sensitive liposomes (coumarin - 6 - PSL - H7K (R2) 2). The ratio of H7K (R2) 2 in coumarin - 6 - PSL - H7K (R2) 2 and the ratio of coumarin - 6 - PSL - H7K (R2) 2 in U87 - MG cells Ingestion way to study. The secondary structure of H7K (R2) 2 at pH 7.4 and pH 6.8 was investigated by using CD technique. The experimental results showed that the targeting effect of H7K (R2) 2 in coumarin - 6 - PSL - H7K (R2) 2 was better than 1% and 3.5%. Cellular uptake assay showed that the entry of coumarin - 6 - PSL - H7K (R2) 2 into U87 - MG cells was unaffected by inhibitors such as phenylephrine, methyl - β - CD and chlorpromazine. The secondary structure of H7K (R2) 2 at pH 6.8 is mostly β - turn. The results of this study indicate that the optimal ratio of H7K (R2) 2 in H7K (R2) 2-modified pH-sensitive liposomes can be determined to be 2.5%. The pathway for H7K (R2) 2-modified pH-sensitive liposomes to enter tumor cells is primarily through the transmembrane peptide-like effect produced by H7K (R2) 2 at low pH. The card-issuing secondary structure of H7K (R2) 2 at pH 6.8 is a possible mechanism of its targeting and penetration.