Division of Biophotonics and Imaging, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Thiruvananthapuram, 695 012 Kerala, India.
Division of In vivo Models and Testing, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Thiruvananthapuram, 695 012 Kerala, India.
Biomaterials. 2018 Jul;171:46-56. doi: 10.1016/j.biomaterials.2018.04.012. Epub 2018 Apr 10.
In magnetic resonance imaging (MRI), gadolinium (Gd) complexes are very often used as contrast agents to enhance the signal from soft tissue deformities and vascular anomalies, to improve the accuracy of diagnosis. The safety concern of using Gd complexes in renally compromised patients pose limitations on its application. To overcome this scenario, we introduce a nontoxic zerovalent iron based nanoparticle as a novel contrast agent for MR angiography and a hybrid version of the same to serve as a dual function contrast agent for targeted liver imaging. The synthesized zerovalent iron (ZVI) nanoparticles after citrate stabilization (C@ZVI) had an average size of 10 nm and exhibited paramagnetic property which is a prerequisite for a positive MRI contrast agent. The longitudinal magnetic relaxivity, r of C@ZVI was 4.93 mMs which is much higher than that of clinically used Gd based agent, gadoterate meglumine (3.6 mMs). For multimodal imaging of the liver, initially the ZVI nanoparticle was tailored with a highly liver specific polysaccharide pullulan, and later with fluorescent carbon dots (Cdts) facilitating both optical and MR imaging. The magnetic relaxivity was retained in P@ZVI-Cdts for T contrast imaging with an r value of 3.48 mMs. The in vivo MR angiogram using C@ZVI and the liver targeted MRI and optical imaging using P@ZVI-Cdts were successfully demonstrated proving their potential as MRA contrast agent and a liver specific multimodal imaging agent.
在磁共振成像（MRI）中，钆（Gd）配合物经常被用作对比剂，以增强软组织变形和血管异常的信号，提高诊断的准确性。在肾功能受损的患者中使用 Gd 配合物存在安全隐患，这限制了其应用。为了克服这种情况，我们引入了一种基于无毒零价铁的纳米颗粒作为新型磁共振血管造影对比剂，并将其混合版本作为靶向肝脏成像的双功能对比剂。经过柠檬酸稳定化后的合成零价铁（ZVI）纳米颗粒（C@ZVI）的平均粒径为 10nm，并表现出顺磁性，这是正磁共振对比剂的前提条件。C@ZVI 的纵向磁弛豫率 r 为 4.93mMs，远高于临床使用的 Gd 基造影剂钆特酸葡甲胺（3.6mMs）。为了对肝脏进行多模态成像，首先将 ZVI 纳米颗粒与高度特异性的肝脏多糖普鲁兰进行修饰，然后与荧光碳点（Cdts）结合，实现光学和磁共振成像。在 P@ZVI-Cdts 中，T 对比成像的磁弛豫率保持不变，r 值为 3.48mMs。成功地进行了 C@ZVI 的体内磁共振血管造影以及 P@ZVI-Cdts 的靶向肝脏磁共振和光学成像，证明了它们作为 MRA 对比剂和肝脏特异性多模态成像剂的潜力。
