Yang Chang-Tong, Hattiholi Aishwarya, Selvan Subramanian Tamil, Yan Sean Xuexian, Fang Wei-Wei, Chandrasekharan Prashant, Koteswaraiah Podili, Herold Christian J, Gulyás Balázs, Aw Swee Eng, He Tao, Ng David Chee Eng, Padmanabhan Parasuraman
Department of Nuclear Medicine and Molecular Imaging, Radiological Sciences Division, Singapore General Hospital, Outram Road, 169608, Singapore; Duke-NUS Medical School, 8 College Road, 169857, Singapore.
Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, 636921, Singapore; School of Biological Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India.
Acta Biomater. 2020 Jul 1;110:15-36. doi: 10.1016/j.actbio.2020.03.047. Epub 2020 Apr 23.
Gd-based contrast agents have been extensively used for signal enhancement of T-weighted magnetic resonance imaging (MRI) due to the large magnetic moment and long electron spin relaxation time of the paramagnetic Gd ion. The key requisites for the development of Gd-based contrast agents are their relaxivities and stabilities which can be achieved by chemical modifications. These modifications include coordinating Gd with a chelator such as diethylenetriamine pentaacetic acid (DTPA) or 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), encapsulating Gd in nanoparticles, conjugation to biomacromolecules such as polymer micelles and liposomes, or non-covalent binding to plasma proteins. In order to have a coherent diagnostic and therapeutic approach and to understand diseases better, the combination of MRI and optical imaging (OI) techniques into one technique entity has been developed to overcome the conventional boundaries of either imaging modality used alone through bringing the excellent spatial resolution of MRI and high sensitivity of OI into full play. Novel MRI and OI bimodal probes have been extensively studied in this regard. This review is an attempt to shed some light on the bimodal imaging probes by summarizing all recent noteworthy publications involving Gd containing MR-optical imaging probes. The several key elements such as novel synthetic strategy, high sensitivity, biocompatibility, and targeting of the probes are highlighted in the review. STATEMENT OF SIGNIFICANCE: The present article aims at giving an overview of the existing bimodal MRI and OI imaging probes. The review structured as a series of examples of paramagnetic Gd ions, either as ions in the crystalline structure of inorganic materials or chelates for contrast enhancement in MRI, while they are used as optical imaging probes in different modes. The comprehensive review focusing on the synthetic strategies, characterizations and properties of these bimodal imaging probes will be helpful in a way to prepare related work.
基于钆（Gd）的造影剂由于顺磁性Gd离子具有大磁矩和长电子自旋弛豫时间，已被广泛用于T加权磁共振成像（MRI）的信号增强。开发基于Gd的造影剂的关键要求是它们的弛豫率和稳定性，这可以通过化学修饰来实现。这些修饰包括将Gd与螯合剂（如二乙烯三胺五乙酸（DTPA）或1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸（DOTA））配位、将Gd封装在纳米颗粒中、与生物大分子（如聚合物胶束和脂质体）共轭或与血浆蛋白非共价结合。为了拥有连贯的诊断和治疗方法并更好地理解疾病，MRI和光学成像（OI）技术已被组合成一种技术实体，通过充分发挥MRI出色的空间分辨率和OI的高灵敏度来克服单独使用任何一种成像方式的传统局限性。在这方面，新型MRI和OI双模态探针已得到广泛研究。本综述试图通过总结所有近期涉及含Gd的磁共振光学成像探针的值得关注的出版物，来阐明双模态成像探针。综述中突出了探针的几个关键要素，如新型合成策略、高灵敏度、生物相容性和靶向性。重要性声明：本文旨在概述现有的双模态MRI和OI成像探针。该综述以一系列顺磁性Gd离子的例子构建，这些离子要么是无机材料晶体结构中的离子，要么是用于MRI造影增强的螯合物，同时它们以不同模式用作光学成像探针。对这些双模态成像探针的合成策略、表征和性质的全面综述将有助于开展相关工作。
