Magnetic Interaction of Multifunctional Core–Shell Nanoparticles for Highly Effective Theranostics

• Published in: Advanced materials (Weinheim) 2018-12, Vol.30 (50), p.e1802444-n/a
• Main Authors: Yang, Ming‐Da, Ho, Chien‐Hsin, Ruta, Sergiu, Chantrell, Roy, Krycka, Kathryn, Hovorka, Ondrej, Chen, Fu‐Rong, Lai, Ping‐Shan, Lai, Chih‐Huang
• Format: Article
• Language: English
• Subjects: Anisotropy; Core-shell particles; Core-shell structure; core–shell; Hyperthermia; In vivo methods and tests; Iron oxides; magnetic interaction; magnetic resonance image; Magnetic resonance imaging; Magnetism; Nanoparticles; NMR; Nuclear magnetic resonance; Surface treatment; theranostics; Tumors
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201802444

The controlled size and surface treatment of magnetic nanoparticles (NPs) make one‐stage combination feasible for enhanced magnetic resonance imaging (MRI) contrast and effective hyperthermia. However, superparamagnetic behavior, essential for avoiding the aggregation of magnetic NPs, substantially limits their performance. Here, a superparamagnetic core–shell structure is developed, which promotes the formation of vortex‐like intraparticle magnetization structures in the remanent state, leading to reduced dipolar interactions between two neighboring NPs, while during an MRI scan, the presence of a DC magnetic field induces the formation of NP chains, introducing increased local inhomogeneous dipole fields that enhance relaxivity. The core–shell NPs also reveal an augmented anisotropy, due to exchange coupling to the high anisotropy core, which enhances the specific absorption rate. This in vivo tumor study reveals that the tumor cells can be clearly diagnosed during an MRI scan and the tumor size is substantially reduced through hyperthermia therapy by using the same FePt@iron oxide nanoparticles, realizing the concept of theranostics. The magnetic interaction among nanoparticles is demonstrated to be able to be manipulated by a core–shell structure to enhance the resolution of magnetic resonance imaging and the specific absorption rate of nanoparticles. It is rather remarkable that the magnetic configuration of the assembly shape can be controlled under a magnetic field toimprove the relaxivity of the contrast agent and the effectiveness of hyperthermia, making theranostics feasible.