Abstract
Diagnostic approaches based on multimodal imaging of clinical noninvasive imaging (eg. MRI/CT scanner) are highly developed in recent years for accurate selection of the therapeutic regimens in critical diseases. Therefore, it is highly demanded in the development of appropriate all-in-one multimodal contrast agents (MCAs) for the MRI/CT multimodal imaging. Here a novel ideal MCAs (F-AuNC@Fe3O4) were engineered by assemble Au nanocages (Au NC) and ultra-small iron oxide nanoparticles (Fe3O4) for simultaneous T1–T2dual MRI and CT contrast imaging. In this system, the Au nanocages offer facile thiol modification and strong X-ray attenuation property for CT imaging. The ultra-small Fe3O4 nanoparticles, as excellent contrast agent, is able to provide great enhanced signal of T1- and T2-weighted MRI (r1 = 6.263 mM−1 s−1, r2 = 28.117 mM−1 s−1) due to their ultra-refined size. After functionalization, the present MCAs nanoparticles exhibited small average size, low aggregation and excellent biocompatible. In vitro and In vivo studies revealed that the MCAs show long-term circulation time, renal clearance properties and outstanding capability of selective accumulation in tumor tissues for simultaneous CT imaging and T1- and T2-weighted MRI. Taken together, these results show that as-prepared MCAs are excellent candidates as MRI/CT multimodal imaging contrast agents.
Highlights
Diagnostic approaches based on multimodal imaging of clinical noninvasive imaging
High-resolution transmission electron microscopy (HRTEM) images of the ultra-small sized Fe3O4 nanoparticles and Au nanocage are shown in Figs S1 and S2 (Supporting Information)
The average diameter of the Fe3O4 nanoparticles is around 2.2 nm with high uniformity, which could provide simultaneous T1 and T2 weight MRI contrast imaging proved in our previous work[9]
Summary
High-resolution transmission electron microscopy (HRTEM) images of the ultra-small sized Fe3O4 nanoparticles and Au nanocage are shown in Figs S1 and S2 (Supporting Information). The enhanced signal of blood vessel can be maintained for more than 6 h, which is much longer than that of Gd complex small molecules with a high excretion rate (about several minutes in small animals)[9,19] These results show that F-AuNC@Fe3O4 can be used for long-term blood pool T1 and T2 modal MRI contrast agent, which is very important in clinical MR imaging[20,21]. To the best of our knowledge, this is the first time that ultra-small sized Fe3O4 and Au nanocages were assembled together to provide simultaneous CT imaging and T1 and T2-modal MRI of tumor bearing mice. The experimental results suggest the potential of F-AuNC@Fe3O4 as a safe and efficient contrast agent for biomedical applications such as multi-modality imaging and molecular diagnostics of diseases in vitro and in vivo, as well as theranostic applications
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