Targeting delivery and deep penetration using multistage nanoparticles for triple-negative breast cancer

Targeting delivery and deep penetration have been attracting tremendous attention in triple-negative breast cancer (TNBC) theranostics. Herein, we reported a novel multistage system (G-AuNPs-DOX-RRGD) with an active targeting effect and size-changeable property to inhibit tumor growth and metastasis in 4T1 xenograft bearing mice. The system was constructed through fabricating small-size gold nanoparticles (AuNPs) onto matrix metalloproteinase-2 (MMP-2) degradable gelatin nanoparticles (GNPs). Doxorubicin (DOX) was tethered onto AuNPs via a pH sensitive hydrazone bond, and RRGD, a tandem peptide of RGD and octarginine, was surface-decorated onto the system to improve its tumor targeting efficiency. In vitro, the G-AuNPs-DOX-RRGD could shrink from 185.9 nm to 71.2 nm after 24 h incubation with MMP-2 and the DOX was released in a pH-dependent manner. Tumor spheroid penetration and collagen diffusion demonstrated G-AuNPs-DOX-RRGD possessed best penetrating efficiency. In vivo, the G-AuNPs-DOX-RRGD actively targeted to the 4T1 tumor and then penetrated through the interstitial matrix, resulted in enhanced accumulation in the deep tumor region. Therefore, the G-AuNPs-DOX-RRGD could approach excellent anti-tumor capacity owing to the synergistic effect of RRGD and the size-changeable property.