pH-Responsive carbon dot-metal organic gel nanocarrier for visible light-triggered chemo-photodynamic cancer therapy and targeted drug delivery.

This abstract describes a novel, stimulus-responsive drug delivery system for cancer therapy, emphasizing a biodegradable, targeted approach to minimize side effects. The system utilizes a Fe-based metal organic coordination gel (MOG) with a porous structure, designed for high-capacity drug loading and Fenton reaction facilitation to destroy cancer cells. The MOG, synthesized via a simple, eco-friendly method, demonstrates peroxidase-like behavior under visible light, enhancing Fenton-type reactions. Carbon dots (CDs), produced through a hydrothermal process, are incorporated for bio-imaging and tracking, while the anti-cancer drug 5 Fluorouracil (5 FU) is loaded with a high capacity of 72.9 %. This system ensures controlled drug release in acidic environments, reducing premature leakage and side effects on healthy cells. A 450 nm light source enhances Fe²⁺ stability, where Fe³⁺ released in acidic cancerous environments converts to Fe²⁺ by photo reduction process and reacts with cellular H₂O₂, producing hydroxyl radicals (HO•) that oxidize critical cellular components, inhibiting cancer growth. Cellular uptake and cytotoxicity were evaluated in various cell lines, with MTT assays revealing selective toxicity to folate-positive HeLa cancer cells, showing reduced effects on comparatively less folate-positive MDA-MB-231 cells and non-cancerous L929 cells. This innovative approach combines pH-responsive chemo-photodynamic therapy with bio-sensing and imaging in one platform, demonstrating significant promise in advanced cancer treatment applications.