As shown in Figure 8C, the internalized (MTX + PEG)-CS-NPs were found initially to be localized
in the lysosomes, as evidenced by the yellow spots in the merged image obtained from the images of the (MTX + PEG)-CS-NPs (green) and late endosomes/lysosomes (red). The result indicated that the (MTX + PEG)-CS-NPs were internalized via the endocytosis pathway into the late endosomes/lysosome [47]. Indeed, after incubation for 4 h, some green fluorescent FITC-labeled (MTX + PEG)-CS-NPs were no longer located in the red fluorescent late endosomes/lysosomes, indicating the successful endo/lysosomal escape. In agreement with other reports [37, 48], these results combined with the results of in vitro drug release and cell selleck chemicals llc viability studies further proved that MTX was released from the (MTX + PEG)-CS-NPs inside the cells by the intracellular protease-mediated selective cleavage of peptide bond. These findings were also in agreement with other reports in the literature [49] that CS possessed the activity to some extent to escape the endo/lysosome. Conclusions We presented the versatile, robust, and easy MTX-based PEGylated CS-NPs while validating MTX as a successful targeting ligand coordinated with a simple anticancer drug, and established the (MTX + PEG)-CS-NPs as a cocktail platform of specific targeting cooperated with enhanced anticancer activity.
MTX was not prematurely released at off-target site but was intensively released at target site due to its sustained/protease-mediated Selleckchem Y 27632 Aspartate drug release characteristic. To the best of our knowledge, the work for the first time explored the validation of Janus role of MTX based on the nanoscaled drug delivery system in vitro. Additionally, as MTX (a targeting ligand/a first drug) was introduced into one kind
of drug carriers, one further advantage was that the drug delivery systems allowed the further introduction of a second ligand or a second drug for synergistic co-targeted delivery or synergistic co-delivery of drugs. Nevertheless, more details about in vivo targeting and anticancer investigations are indispensable to obtain a better understanding of the therapeutic effect of the (MTX + PEG)-CS-NPs, and relevant studies are in process. Authors’ information Both authors FL and YL contributed equally and mTOR inhibitor should be considered as co-first authors. Acknowledgements Fanghong Luo acknowledges the financial support by the Natural Science Foundation of Fujian Province of China (Grant No. 2013 J01384) and Science and Technology Foundation of Xiamen of China (Grant No. 3502Z20113012). Dr. Yuan Jiang is acknowledged for useful discussions and editing the manuscript. References 1. Peer D, Karp JM, Hong S, Farokhzad OC, Margalit R, Langer R: Nanocarriers as an emerging platform for cancer therapy. Nat Nanotechnol 2007, 2:751–760.