1D Coordination Polymer Nanofibers for Low‐Temperature Photothermal Therapy

TLDR

Near‑infrared photothermal therapy typically requires hyperthermia above 50 °C, which can damage healthy tissue and leave internal tumor regions untreated. The study aims to enable effective tumor ablation at lower temperatures to improve clinical safety of PTT. The authors fabricated PEG‑modified one‑dimensional coordination polymers (Mn‑ICG@pHis‑PEG) that are biodegradable, possess large surface area, exhibit pH‑responsive tumor retention, and can load the heat‑shock protein 90 inhibitor gambogic acid to sensitize cancer cells to heat. The Mn‑ICG@pHis‑PEG/GA system induces tumor cell apoptosis at ~43 °C, achieving efficient low‑temperature photothermal therapy with excellent tumor destruction and minimal invasiveness.

Abstract

Abstract Near‐infrared (NIR)‐light‐triggered photothermal therapy (PTT) usually requires hyperthermia to >50 °C for effective tumor ablation, which can potentially induce inflammatory disease and heating damage of normal organs nearby, while tumor lesions without sufficient heating (e.g., the internal part) may survive after treatment. Achieving effective tumor killing under relatively low temperatures is thus critical toward successful clinical use of PTT. Herein, we design a simple strategy to fabricate poly(ethylene glycol) (PEG)‐modified one‐dimensional nanoscale coordination polymers (1D‐NCPs) with intrinsic biodegradability, large surface area, pH‐responsive behaviors, and versatile theranostic functions. With NCPs consisting of Mn2+/indocyanine green (ICG) as the example, Mn‐ICG@pHis‐PEG display efficient pH‐responsive tumor retention after systemic administration and then load Gambogic acid (GA), a natural inhibitor of heat‐shock protein 90 (Hsp90) that plays an essential role for cells to resist heating‐induced damage. Such Mn‐ICG@pHis‐PEG/GA under a mild NIR‐triggered heating is able to induce effective apoptosis of tumor cells, realizing low‐temperature PTT (~43 °C) with excellent tumor destruction efficacy. This work not only develops a facile approach to fabricate PEGylated 1D‐NCPs with tumor‐specific pH responsiveness and theranostic functionalities, but also presents a unique low‐temperature PTT strategy to kill cancer in a highly effective and minimally invasive manner.