An NIR-activated polymeric nanoplatform with ROS- and temperature-sensitivity for combined photothermal therapy and chemotherapy of pancreatic cancer.

Nanomedicine has attracted growing attention due to its designability and functionality, as well as its excellent pharmacokinetics with limited side effects, and recently, combined therapies have become desirable as they can obtain enhanced therapeutic efficacy by using nanomedicine. Herein, we have reported a functional drug delivery system with a dual response to temperature and reactive oxygen species to efficiently eliminate pancreatic cancer cells in a combined therapy strategy. Functional micelles with camptothecin (CPT) in the core and indocyanine green (ICG) on the surface could effectively accumulate in tumor sites through the EPR effect. The ROS in the tumor microenvironment trigger the conversion of an amino-based copolymer to a carboxy based copolymer, releasing the loaded ICG to reduce the size of the micelles with high penetration in tumor tissue. On the one hand, under 808 nm light irradiation, the micelles will produce the heat to kill tumor cells via photothermal therapy. On the other hand, the generated heat could further trigger the transition of a copolymer from a hydrophobic to a hydrophilic state, releasing the loaded CPT into the deep tumor cells to achieve chemotherapy. The in vitro and in vivo experiments revealed that this combined therapy could combat pancreatic cancer cells with an enhanced therapeutic effect.

Photothermal Therapy Nanomaterials Boosting Transformation of Fe(III) into Fe(II) in Tumor Cells for Highly Improving Chemodynamic Therapy.

Chemodynamic therapy based on Fe2+-catalyzed Fenton reaction holds great promise in cancer treatment. However, low-produced hydroxyl radicals in tumor cells constitute its severe challenges because of the fact that Fe2+ with high catalytic activity could be easily oxidized into Fe3+ with low catalytic activity, greatly lowering Fenton reaction efficacy. Here, we codeliver CuS with the iron-containing prodrug into tumor cells. In tumor cells, the overproduced esterase could cleave the phenolic ester bond in the prodrug to release Fe2+, activating Fenton reaction to produce the hydroxyl radical. Meanwhile, CuS could act as a nanocatalyst for continuously catalyzing the regeneration of high-active Fe2+ from low-active Fe3+ to produce enough hydroxyl radicals to efficiently kill tumor cells as well as a photothermal therapy agent for generating hyperthermia for thermal ablation of tumor cells upon NIR irradiation. The results have exhibited that the approach of photothermal therapy nanomaterials boosting transformation of Fe3+ into Fe2+ in tumor cells can highly improve Fenton reaction for efficient chemodynamic therapy. This strategy was demonstrated to have an excellent antitumor activity both in vitro and in vivo, which provides an innovative perspective to Fenton reaction-based chemodynamic therapy.

Erythrocyte membrane is an alternative coating to polyethylene glycol for prolonging the circulation lifetime of gold nanocages for photothermal therapy.

Gold nanocages (AuNCs), which have tunable near-infrared (NIR) absorption and intrinsically high photothermal conversion efficiency, have been actively investigated as photothermal conversion agents for photothermal therapy (PTT). The short blood circulation lifetime of AuNCs, however, limits their tumor uptake and thus in vivo applications. Here we show that such a limitation can be overcome by cloaking AuNCs with red blood cell (RBC) membranes, a natural stealth coating. The fusion of RBC membranes over AuNC surface does not alter the unique porous and hollow structures of AuNCs, and the resulting RBC-membrane-coated AuNCs (RBC-AuNCs) exhibit good colloidal stability. Upon NIR laser irradiation, the RBC-AuNCs demonstrate in vitro photothermal effects and selectively ablate cancerous cells within the irradiation zone as do the pristine biopolymer-stealth-coated AuNCs. Moreover, the RBC-AuNCs exhibit significantly enhanced in vivo blood retention and circulation lifetime compared to the biopolymer-stealth-coated counterparts, as demonstrated using a mouse model. With integrated advantages of photothermal effects from AuNCs and long blood circulation lifetime from RBCs, the RBC-AuNCs demonstrate drastically enhanced tumor uptake when administered systematically, and mice that received PPT cancer treatment modulated by RBC-AuNCs achieve 100% survival over a span of 45 days. Taken together, our results indicate that the long circulating RBC-AuNCs may facilitate the in vivo applications of AuNCs, and the RBC-membrane stealth coating technique may pave the way to improved efficacy of PPT modulated by noble metal nanoparticles.