Angiopep-2 and activatable cell penetrating peptide dual modified nanoparticles for enhanced tumor targeting and penetrating

Delivering chemotherapeutics by nanoparticles into tumor was influenced by at least two factors: specific targeting and highly efficient penetrating of the nanoparticles. In this study, two targeting ligands, angiopep-2 and activatable cell penetrating peptide (ACP), were functionalized onto nanoparticles for tumor targeting delivery. In this system, angiopep-2 is a ligand of low-density lipoprotein receptor-related protein-1 (LRP1) which was highly expressed on tumor cells, and the ACP was constructed by the conjugation of RRRRRRRR (R8) with EEEEEEEE through a matrix metalloproteinase-2 (MMP-2) sensitive linker, enabling the ACP with tumor microenvironment-responsive cell penetrating property. 4h incubation of ACP with MMP-2 leads to over 80% cleavage of ACP, demonstrating ACP indeed possessed MMP-2 responsive property. The constructed dual targeting nanoparticles (AnACNPs) were approximately 110 nm with a polydispersity index of 0.231. In vitro, ACP modification and angiopep-2 modification could both enhance the U-87 MG cell uptake because of the high expression of MMP-2 and LRP-1 on C6 cells. AnACNPs showed higher uptake level than the single ligand modified nanoparticles. The uptake of all particles was time- and concentration-dependent and endosomes were involved. In vivo, AnACNPs showed best tumor targeting efficiency. The distribution of AnACNPs in tumor was higher than all the other particles. After microvessel staining with anti-CD31 antibody, the fluorescent distribution demonstrated AnACNPs could distribute in the whole tumor with the highest intensity. In conclusion, a novel drug delivery system was developed for enhanced tumor dual targeting and elevated cell internalization.