Magnetic resonance imaging contrast agents are currently designed by modifying their structural and physiochemical properties to improve relaxivity and to enhance image contrast. Here, we show a general method for increasing relaxivity by confining contrast agents inside the nanoporous structure of silicon particles. Magnevist, gadofullerenes and gadonanotubes were loaded inside the pores of quasi-hemispherical and discoidal particles. For all combinations of nanoconstructs, a boost in longitudinal proton relaxivity r 1 was observed: Magnevist, r1≈14 mM-1 s -1/Gd3+ ion (∼8.15×10+7 mM -1s-1/construct); gadofullerenes, r1 ≈ 200 mM-1s-1/Gd3+ ion (∼7×10+9 mM-1s-1/construct); gadonanotubes, r1 ≈ 150 mM-1s-1/Gd3+ion(∼2×10 -1+9 mM-1s-1/construct). These relaxivity values are about 4 to 50 times larger than those of clinically available gadolinium-based agents (∼4 mM-1s-1/Gd 3+ ion). The enhancement in contrast is attributed to the geometrical confinement of the agents, which influences the paramagnetic behaviour of the Gd3+ ions. Thus, nanoscale confinement offers a new and general strategy for enhancing the contrast of gadolinium-based contrast agents.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering