Modulatable endosomalytic, intracellularly biodegradable vectors for gene delivery

摘要

In order to achieve efficient gene delivery, we have designed p(K_a) modulatable oligopeptides (2COPs) by combining with lysine, histidine and cysteine residues which will bind DNA extracellularly, internalize via endocytosis, provide a tunable endosomal release mechanism, and provide a degradable backbone in order that the DNA can be released once in the cytoplasm. The reducible polycations (RPCs) were synthesized from 2COPs. The sizes, surface charges and the stability of RPC polyplexes under the simulated physiological conditions extra- and intracellularly suggested that these RPCs are promising vectors. In addition, the transfections revealed that the RPCs can facilitate endosomal buffering and intracellular reduction and are non-toxic to cells. The nuclear targeting signal (TAT) was incorporated into these vectors. The reducible copolycations (RcPCs) were synthesized via oxidative polymerisation between 2COPs and TAT. The RcPC polyplexes are ~100 nm, and are positively charged. Gel shift assay revealed that RcPCs have less potential than RPCs to be used as vectors as they are less stable extracellularly than the RPCs. In addition, chloroquine was required to enhance the transfection of RcPCs. Furthermore, there is no improvement in transfection of RcPC compared to RPCs. Therefore, this suggests that the incorporation of TAT does not improve the transfection.