Copper-Cysteamine Nanoparticles as a Heterogeneous Fenton-Like Catalyst for Highly Selective Cancer Treatment.

Herein, for the first time, we report copper-cysteamine (Cu-Cy) nanoparticles having Cu1+ instead of Cu2+ as an efficient heterogeneous Fenton-like catalyst for highly selective cancer treatment. Initial measurements of Cu-Cy's hydroxyl radical generation ability show that it behaves as a Fenton-like reagent in the presence of H2O2 (100 μM) at pH 7.4, and that its Fenton-like activity is dramatically enhanced under acidic conditions (pH 6.5 and 5.5). Notably, Cu-Cy exhibits high stability and minimal copper release during the Fenton-like reaction, demonstrating its potency as a heterogeneous Fenton-like catalyst with a low cytotoxic effect. Through extensive in vitro studies, Cu-Cy NPs are found to generate a significantly higher level of ROS, thereby causing significantly more destruction to cancerous cells than to normal cells without the need for exogenous additives, such as H2O2. To the best of our knowledge, the average IC-50 value of Cu-Cy to cancer cells (11 μg/mL) is the lowest among reported heterogeneous Fenton-like nanocatalyst so far. Additionally, compared to cancer cells, Cu-Cy NPs display substantially higher IC-50 value toward normal cells (50 μg/mL), suggesting high selectivity. Overall, Cu-Cy NPs can participate in heterogeneous Fenton-like activity with elevated H2O2 under acidic conditions to produce significantly higher levels of hydroxyl radicals in cancer cells when compared to normal cells, resulting in selective cytotoxicity to cancer cells.