ICG/ l -Arginine Encapsulated PLGA Nanoparticle-Thermosensitive Hydrogel Hybrid Delivery System for Cascade Cancer Photodynamic-NO Therapy with Promoted Collagen Depletion in Tumor Tissues

Photodynamic therapy (PDT) is promising for clinical cancer therapy; however, the efficacy was limited as an individual treatment regimen. Here, an approach synergistically combining PDT and nitric oxide (NO) gas therapy along with destruction of the tumor extracellular matrix (ECM) was presented to eliminate cancer. Specifically, the NO donor l -arginine ( l -Arg) and the photosensitizer indocyanine green (ICG) were co-encapsulated in poly(lactic-glycolic acid) (PLGA) nanoparticles and then loaded into the poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL–PEG–PCL) hydrogel to develop an injectable, thermosensitive dual drug delivery system (PLGA@ICG@ l -Arg/Gel). Significantly, reactive oxygen species (ROS) produced by PLGA@ICG@ l -Arg/Gel under near-infrared (NIR) light irradiation could not only result in the apoptosis of cancer cells but also oxidize l -Arg to generate NO, which could suppress the proliferation of cancer cells. Moreover, ROS could further oxidize NO to generate peroxynitrite anions (ONOO – ). ONOO – could activate matrix metalloproteinases (MMPs), which notably degraded collagen in ECM so as to damage the tumor microenvironment. PLGA@ICG@ l -Arg/Gel significantly increased the antitumor efficacy against highly malignant 4T1 tumors in mice. Taken together, PLGA@ICG@ l -Arg/Gel is a multifunctional platform that provides a novel strategy for cancer treatment with cascade amplification of the ROS oxidation effect, which holds great potential in clinical translation.