Redoxable heteronanocrystals functioning magnetic relaxation switch for activatable T1 and T2 dual-mode magnetic resonance imaging.
T1/T2 dual-mode magnetic resonance (MR) contrast agents (DMCAs) have gained much attention because of their ability to improve accuracy by providing two pieces of complementary information with one instrument. However, most of these agents are "always ON" systems that emit MR contrast regardless of their interaction with target cells or biomarkers, which may result in poor target-to-background ratios. Herein, we introduce a rationally designed magnetic relaxation switch (MGRS) for an activatable T1/T2 dual MR imaging system. Redox-responsive heteronanocrystals, consisting of a superparamagnetic Fe3O4 core and a paramagnetic Mn3O4 shell, are synthesized through seed-mediated growth and subsequently surface-modified with polysorbate 80. The Mn3O4 shell acts as both a protector of Fe3O4 in aqueous environments to attenuate T2 relaxation and as a redoxable switch that can be activated in intracellular reducing environments by glutathione. This simultaneously generates large amounts of magnetically decoupled Mn(2+) ions and allows Fe3O4 to interact with the water protons. This smart nanoplatform shows an appropriate hydrodynamic size for the EPR effect (10-100 nm) and demonstrates biocompatibility. Efficient transitions of OFF/ON dual contrast effects are observed by in vitro imaging and MR relaxivity measurements. The ability to use these materials as DMCAs is demonstrated via effective passive tumor targeting for T1- and T2-weighted MR imaging in tumor-bearing mice.
Department of Chemical and Biomolecular Engineering, College of Engineering, Yonsei University, Seoul, 120-749, Republic of Korea.
Myeong-Hoon
MH
Kim
Department of Radiology, College of Medicine, Yonsei University, Seoul, 120-752, Republic of Korea.
Hye-Young
HY
Son
Department of Chemical and Biomolecular Engineering, College of Engineering, Yonsei University, Seoul, 120-749, Republic of Korea.
Ga-Yun
GY
Kim
Department of Radiology, College of Medicine, Yonsei University, Seoul, 120-752, Republic of Korea.
Kwangyeol
K
Park
Department of Radiology, College of Medicine, Yonsei University, Seoul, 120-752, Republic of Korea; YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul, 120-752, South Korea. Electronic address: ymhuh@yuhs.ac.
Yong-Min
YM
Huh
Department of Chemical and Biomolecular Engineering, College of Engineering, Yonsei University, Seoul, 120-749, Republic of Korea. Electronic address: haam@yonsei.ac.kr.
Seungjoo
S
Haam
D000818:Animals; D003287:Contrast Media / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008297:Male; D017895:Manganese Compounds / Q000737:chemistry*; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009369:Neoplasms / Q000000981:diagnostic imaging*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size
D003287:Contrast Media; D058185:Magnetite Nanoparticles; D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D005978:Glutathione
Dual-mode contrast agent; Glutathione; MR imaging; Magnetic nanoparticles; Stimuli-responsive