Modular Assembly of Drug and Monodisperse SPIONs for Superior Magnetic and T₂-Imaging Performance

Development of superparamagnetic iron oxide nanoparticles (SPIONs) based theranostics has suffered due to its self-contradictory requirements on water dispersity and drug loadings. Generally well-dispersed SPIONs have excellent MRI performance but are insensitive to magnetism mediated delivery. Besides, loading hydrophobic drugs also hampers the stability of SPIONs which is critical for their biomedical applications. Considering these aspects, we employed curcumin as a cross-linking agent to facilitate the modular assembly of drug and monodisperse SPIONs (Cur/ALN-β-CD-SPIONs). Interestingly, the saturation magnetization of Cur/ALN-β-CD-SPIONs is higher than that of ALN-β-CD-SPIONs, and the value of r₂ indicating the negative contrast ability increases to 389.96 mM^-1 s^-1. Furthermore, the Cur/ALN-β-CD-SPIONs are very stable in PBS buffer over 3 weeks. The mice treated with Cur/ALN-β-CD-SPIONs by tail vein injection displayed a better tumor inhibition effect than that of free curcumin. This study provides a simple method for modular assembly of drug and monodisperse SPIONs, which is crucial to the design of SPIONs with superior T₂-imaging performance and drug delivery.