Multifunctional nanoprobe for MRI/optical dual-modality imaging and radical scavenging.

The development of novel nanomaterials for the diagnosis and/or treatment of human diseases has become an important issue. In this work, a multifunctional theranostic agent was designed by covalently binding hydroxyl- and amino-bearing C60 derivatives (C60 O∼10 (OH)∼16 (NH2 )∼6 (NO2 )∼6 ⋅24 H2 O) with gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) to yield C60 O∼10 (OH)∼16 (NH2 )∼6 (NO2 )∼6 ⋅24 H2 O/(Gd-DTPA)3 (DF1 Gd3 ). The obtained DF1 Gd3 shows more than fourfold contrast improvement over commercial Gd-DTPA along with multiwavelength fluorescent emission for dual-modality diagnosis. An inner-ear magnetic resonance imaging (MRI) study was designed as a model of biological barriers, including the blood/brain barrier (BBB) for DF1 Gd3 to investigate its in vivo behavior. This revealed that the fabricated contrast agent dramatically increases the local contrast but can not cross the middle ear/inner ear barrier and endolymph/perilymph barrier in the inner ear, and thus it is also BBB-prohibited in normal individuals. In vivo biodistribution studies suggested that 1) DF1 Gd3 could circulate in vessels for a relatively long time and is mainly eliminated through liver and kidney, 2) DF1 Gd3 may potentially function as a liver-specific MRI contrast agent. Interestingly, DF1 Gd3 also shows an excellent quenching effect on hydroxyl radicals, as revealed by the DMPO spin trap/ESR method. The combination of enhanced MRI/FL imaging and local treatment of lesions is unique to DF1 Gd3 and potentiates the medical paradigm of "detect and treat/prevent" in combating human diseases related to reactive oxygen.