Development of Spin Probes for Cell-tagging and Oximetry

描述(申请人提供)：能够检测和成像分子目标、细胞和组织异常的非侵入性方法将在生物医学研究中具有价值。磁性纳米造影剂标记细胞已成为利用MRI技术进行活体成像的有力工具。这项提议的目标是开发用于细胞和组织的磁共振成像的新型多功能顺磁探针。我们已经确定了一类新的顺磁性晶体材料，可以通过电子顺磁共振(EPR)光谱和成像直接检测到，具有明显更高的灵敏度和空间分辨率。它们是由锂化大环的中性自由基堆叠而成的，它们是邻苯二甲酸和大环。由于未成对电子之间的强交换耦合，这些探针的EPR谱具有单一且非常窄的EPR吸收的特征。此外，这种微粒将具有独特的优势，可以感知和报告细胞和组织的氧水平，具有显著的氧敏感性和生物稳定性，能够在较长时间内精确、准确和重复地测量和绘制组织中的氧浓度。这些微粒可以制备成亚微米大小，并通过内吞作用有效地内化，而不需要包裹、涂层或附着到特定的受体上。这些颗粒的独特性质可以通过将它们内化到细胞和特定组织中来可视化细胞的增殖、迁移和运输，类似于磁共振中使用的超顺磁性颗粒。提出了以下五个具体目标：1.设计、合成、表征和配制用作氧气、细胞跟踪和成像生物传感器的新型顺磁自旋微粒；2.表征该微粒对细胞和组织的体内外分布和毒性；3.细胞内微粒的内化(细胞摄取)和表征；4.建立用于细胞和体内组织和血管血氧测定应用的微粒自旋探针；5.建立用于全身微粒摄取和分布成像、细胞摄取微粒和细胞跟踪的微粒自旋探针。这些探头的使用将增强我们进行生物医学成像的能力，并在细胞治疗和组织工程领域提供令人兴奋的新机会。

DESCRIPTION (provided by applicant): Non-invasive methods capable of detection and imaging of molecular targets, cells and tissue abnormalities will be valuable in biomedical research. Cell labeling with magnetic nanoparticulate contrast agents has emerged as a powerful tool for in vivo imaging using MRI technique. The objective of this proposal is to develop novel multifunctional paramagnetic probes for use in magnetic resonance-based imaging of cells and tissues. We have identified a new class of paramagnetic crystalline materials that can be directly detected by electron paramagnetic resonance (EPR) spectroscopy and imaging with markedly higher sensitivity and spatial resolution. They are composed of stacks of neutral free radicals of lithiated phthalonaphthalo- and anthracyanine macrocycles. The EPR spectrum of these probes is characterized by a single and very narrow EPR absorption due to strong exchange coupling between the unpaired electrons. In addition, the particulates will have the unique advantages of sensing and reporting cellular and tissue oxygen levels with remarkable oxygen sensitivity and biostability enabling precise, accurate and repeated measurement and mapping of oxygen concentration in tissues over extended periods of time. The particulates can be prepared in submicron sizes and efficiently internalized by endocytosis without encapsulation, coatings or attachment to specific receptors. The unique properties of these particulates can be exploited by internalizing them into cells and in specific tissues to visualize cell proliferation, migration and trafficking, similar to superparamagnetic particulates used in MRI. The following five specific aims are proposed: 1. Design, synthesis, characterization and formulation of novel paramagnetic spin particulates for use as biosensors of oxygen, cell-tracking and imaging; 2. Characterization of in vitro and in vivo distribution and toxicity of the particulates to cells and tissues; 3. Internalization (cellular uptake) and characterization of particulates in cells; 4. Establishment of the particulate spin probes for cellular and in vivo tissue and vascular oximetry applications; 5. Establishment of the particulate spin probes for in vivo applications such as whole-body imaging of particulate uptake and distribution, particulate uptake by cells and cell tracking. The availability of these probes will enhance our ability to perform biomedical imaging and offer exciting new opportunities in the field of cell therapy and tissue engineering.