Novel Redox-Responsive Polymeric Magnetosomes with Tunable Magnetic Resonance Property for In Vivo Drug Release Visualization and Dual-Modal Cancer Therapy

Monitoring of in vivo drug release from nanotheranostics by noninvasive approaches remains very challenging. Herein, novel redox-responsive polymeric magnetosomes (PolyMags) with tunable magnetic resonance imaging (MRI) properties are reported for in vivo drug release monitoring and effective dual-modal cancer therapy. The encapsulation of doxorubicin (DOX) significantly decreases PolyMags' T₂-contrast enhancement and transverse relaxation rate R₂, depending on the drug loading level. The T₂ enhancement and R₂ can be recovered once the drug is released upon PolyMags' disassembly. T₂- and T₂*-MRI and diffusion-weighted imaging (DWI) are utilized to quantitatively study the correlation between MRI signal changes and drug release, and discover the MR tuning mechanisms. The in vivo drug release pattern is visualized based on such tunable MRI capability via monitoring the changes in T₂-weighted images, T₂ and T₂* maps, and R₂ and R₂* values. Interestingly, the PolyMags possess excellent photothermal effect, which can be further enhanced upon DOX loading. The PolyMags are highly efficacious to treat breast tumors on xenograft model with tumor-targeted photothermal- and chemotherapy, achieving a complete cure rate of 66.7%. The concept reported here is generally applicable to other micellar and liposomal systems for image-guided drug delivery and release applications toward precision cancer therapy.