Biodegradable FeWO_x nanoparticles for CT/MR imaging-guided synergistic photothermal, photodynamic, and chemodynamic...

The development of a simple and effective single constituent multifunctional nanotheranostic platform producing a multimodality diagnostic signal and curing effect is still a challenge. Herein, we synthesized simple and biodegradable FeWO_x ternary oxide nanoparticles and modified their surface with RGD-PEG-NH₂ (FeWO_x-PEG-RGD NPs), whereby resulting NPs possessed a (T₂/T₁) switchable MRI/CT dual-modal imaging ability and synergistic photothermal therapy (PTT)/photodynamic therapy (PDT)/chemodynamic therapy (CDT) capacity. We showed that FeWO_x-PEG-RGD NPs enabled tumor accumulation under a magnetic field drive and RGD-mediated tumor penetration and implemented PTT/PDT treatment under 980 nm laser irradiation. In an acidic tumor microenvironment (TME) with a high hydrogen peroxide (H₂O₂) expression, NPs degraded to release Fe³⁺ and Fe²⁺, triggering a Fenton reaction to generate ˙OH for CDT. The released Fe²⁺ led to T₂/T₁ signal conversion for tracing cancer therapy, while the high X-ray attenuation coefficient of W also made it a good CT contrast agent for guided therapy. Thus, the structurally simple FeWO_x-PEG-RGD was capable of mediating (T₂/T₁-weighted) MR/CT two modal imaging-guided PTT/PDT/CDT synergic therapy with a high accuracy and superb anticancer efficiency. The simple, degradable, rapid-clearance, and multifunctional FeWO_x-PEG-RGD NPs provide a novel, promising, and versatile nanotheranostic platform.