DOX/ICG-carrying γ-PGA-g-PLGA-based polymeric nanoassemblies for acid-triggered rapid DOX release combined with NIR-activated photothermal effect

Abstract

To boost the efficacy of chemo-photothermal cancer treatment by the intracellular rapid release of doxorubicin (DOX) combined with near-infrared (NIR)-triggered photothermal effect of indocyanine green (ICG), the poly(γ-glutamic acid)-g-poly(lactic-co-glycolic acid) (γ-PGA-g-PLGA)-based polymeric nanoassemblies (PNAs) with simultaneous incorporation of DOX and ICG were developed in this work by simple one-step nanoprecipitation. The obtained DOX/ICG-loaded PNAs were characterized by a compact γ-PGA/DOX complexes-encapsulated PLGA-rich core covered with the co-assembly of amphiphilic D-α-tocopheryl polyethylene glycol succinate (TPGS), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)] (DSPE-PEG) and ICG molecules. The robust cargo-loaded PNAs not only promoted the photo-stability of ICG in PBS, but also reduced ICG leakage from PNAs. With the milieu pH being altered from 7.4 to 5.0, the massive disruption of ionic DOX/γ-GA complexes and PLGA degradation considerably accelerated DOX release from payload-containing PNAs. The results of in vitro cellular uptake revealed that the DOX/ICG-loaded PNAs appreciably enhanced the cellular uptake of payloads by HeLa cells. Notably, through the intracellular acid-triggered rapid DOX release combined with the ICG-based NIR-activated hyperthermia and singlet oxygen generation, the combination therapy of DOX/ICG-loaded PNAs can use lower dosage of drugs to effectively inhibit proliferation of HeLa cells compared to the chemo or photothermal treatment alone, thus showing the great potential to improve efficacy of cancer treatment.