Ferrous-cysteine–phosphotungstate nanoagent with neutral pH fenton reaction activity for enhanced cancer chemodynamic therapy

The key bottleneck problem of chemodynamic therapy (CDT) is that the efficiency depends heavily on an acidic chemical environment. However, there is a sufficient blood supply on the surface of solid tumours, resulting in neutral-pH surface regions, strongly reducing the effectiveness of CDT. In this study, chelating complex ferrous-cysteine-phosphotungstate nanoparticles (FcPWNPs) are synthesized to serve as new CDT nanoagents that break through the limitation of a neutral pH, ensuring CDT efficiencies at both an acidic and neutral pH. The CDT efficiency is increased by introducing cysteine and phosphotungstate, which form an Fe chelating complex to inhibit the formation of inert Fe(OH)(x), and accelerate electron transfer between ferric and ferrous ions, respectively. Due to this ferrous chelating strategy and associated electron transfer property, the FcPWNPs can destroy cancer cells from the neutral-pH tumour surface to the acidic interior, thus realizing a complete CDT cancer therapy.