Journal of Chinese Pharmaceutical Sciences ›› 2015, Vol. 24 ›› Issue (10): 660-665.DOI: 10.5246/jcps.2015.10.084

• Original articles • Previous Articles     Next Articles

The targeting effect of H7K(R2)2-modified pH-sensitive liposomes on U87-MG cells

Yang Zhao1, Wei Ren1, Ting Zhong1, Chao Wang1, Weiqiang Zhang1, Dan Huang1, Shuang Zhang1, Yang Guo1, Xin Yao1, Xuan Zhang1*, Qiang Zhang1,2    

  1. 1. Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
    2. State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, Beijing 100191, China
  • Received:2015-05-22 Revised:2015-06-22 Online:2015-10-21 Published:2015-07-12
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  • Supported by:

    Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20120001110012) and the National Basic Research Program of China (973 Program, Grant No. 2013CB932501) and National Natural Science Foundation of China (Grant No. 81172992).


The present study aimed to investigate the targeting effect of H7K(R2)2-modified pH-sensitive liposomes on U87-MG cells. Using coumarin-6 as a fluorescence probe, we prepared H7K(R2)2-modified pH-sensitive liposomes (designated as coumarin-6-PSL-H7K(R2)2). The flow cytometry assay was used to evaluate the effect of H7K(R2)2 proportions on the cellular uptake and endocytosis pathways of coumarin-6-PSL-H7K(R2)2 on U87-MG cells. The circular dichroism (CD) spectroscopy assay was used to investigate the secondary structures of H7K(R2)2 peptide at pH 7.4 and pH 6.8, respectively. Our results indicated that the 2.5% proportion of H7K(R2)2 in the coumarin-6-PSL-H7K(R2)2 was superior to those of 1% and 3.5% of H7K(R2)2. The uptake of coumarin-6-PSL-H7K(R2)2 on U87-MG cells was not inhibited by filipin, M-β-CD or chlorpromazine. The secondary structure of H7K(R2)2at pH 6.8 was mostly presented as β-turn. In conclusion, we suggested that the appropriate proportion of H7K(R2)2 in the H7K(R2)2-modified pH-sensitive liposomes could be set at 2.5%. The cellular uptake pathway for H7K(R2)2-modified pH-sensitive liposomes was via the cell penetrating capacity of H7K(R2)2 which responded to acidic condition. The secondary structure of H7K(R2)2 at pH 6.8, which was presented as the shape of hairpin, might be mainly responsible for its targeting and cell penetrating effect.

Key words: H7K(R2)2-modified, pH-sensitive liposomes, Cellular uptake pathway, Secondary structure, U87-MG cells

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