| Multi-functional nano drug delivery systems have attracted more attention in pharmaceutical research as a carrier for anti-tumor therapy. However, current drug delivery systems are far from optimal on account of structural instability in blood circulation, nonspecific cellular internalization, and inefficient intracellular drug release. By responding to the endogenous occurring difference between the extra-and intra-cellular redox environments (100?1000 folds) and the elevated production of reducing substances (7?10 folds) in tumor cells than normal cells, a A54 peptide modified and PEGylated reduction cleavable glucolipid conjugate (A54-PEG-CSO-ss-SA) was designed. The peptide A54 (sequence:AGKGTPSLETTP) was identified from a phase-display random peptide library by in vivo panning, which was the most effective peptide to the human hepatoma cell line BEL-7402.This study was aimed to the prolongation of the blood circulation time, the increase of the tumor cellular uptake and the efficient drug release in the tumor cells.The selective redox-response conjugate (CSO-ss-SA) was synthesized by the reactions between carboxyl groups of 3,3'-dithiodipropionic acid and the free amino groups from stearylamine and chitosan. The A54-PEG-CSO-ss-SA conjugate was synthesized by conjugating the A54 peptide through the PEG chains to the CSO-ss-SA in the presence of EDC and NHS. The synthesized A54-PEG-CSO-ss-SA could self-assemble into micelles in aqueous water above the critical micelle concentration (54.9 ?g/mL). The particle size was 50.83±10.42 nm with a uniform spherical shape. The model drug doxorubicin (DOX) was encapsulated into the A54-PEG-CSO-ss-SA micelles using the dialysis method to form A54-PEG-CSO-ss-SA/DOX. The drug encapsulation efficiency was 77.92% and the particle size decreased to 48.36±4.3 nm. The A54-PEG-CSO-ss-SA showed an improved redox sensitivity which only degraded fast and released drug in 10 mM levels of glutathione (GSH). The results of cellular uptake indicated that the A54-PEG-CSO-ss-SA micelles could delivery the DOX into cytoplasm faster compared to the CSO-ss-SA micelles in the the model cell lines BEL-7402 and HepG2 cells. Utilizing nile red (NR) as the model drug, in contrast with non-responsive conjugate A54-PEG-CSO-SA, A54-PEG-CSO-ss-SA released drug more quickly in response to the high level of GSH concentration in tumor cells. The IC50 value of A54-PEG-CSO-ss-SA/DOX was 1.34±0.58?g/mL, which was 0.6-1.0 fold lower compared with CSO-ss-SA/DOX and A54-PEG-CSO-SA.Using the BALB/C+/nu nude mice bearing BEL-7402 xenografts as the model, the non-invasive NIR imaging technique was applied to monitor the time dependent qualitative biodistribution of DiR-labeled CSO-ss-SA and A54-PEG-CSO-ss-SA micelles. The results showed that A54-PEG-CSO-ss-SA micelles had stronger distribution ability to liver and hepatoma tissue in vivo and prolonged the circulation and retention time, which can benefit the pharmacological action exerted by DOX. Furthermore, NR loaded A54-PEG-CSO-ss-SA were used to observe the drug release behaviors in vivo. Triggered NR release from A54-PEG-CSO-ss-SA occurred only in the tumor tissue showing selective redox sensitivity, which was produced by the special higher GSH concentration. While in the organs liver and heart, only a few NR fluorescence signals were observed in 48 h. The tumor inhibition rate of A54-PEG-CSO-ss-SA/DOX was 82.93%, which was equal to that of the commercial doxorubicin hydrochloric, and significantly better than that of CSO-ss-SA/DOX and A54-PEG-CSO-SA at the same doses.In conclution, this study suggested that the A54-PEG-CSO-ss-SA modified by A54 peptide showed promising potential to cure the tumor for its efficient and special tumor targeting, enhanced antitumor activity, selective intracellular drug release and reduced toxicity of normal tissue and heart. |
PDF Full Text Request