动脉硬化从脂质条纹的发生到最终斑块破裂，巨噬细胞都起着重要作用。因此，巨噬细胞的识别及定量成为判断动脉斑块稳定与否的一个重要标志，是如今研究的热点。鉴于纳米级造影剂具有极强的穿透力，本研究设想如果能够通过携带靶向分子探针的纳米造影剂进行斑块内巨噬细胞超声成像，将对动脉粥样硬化患者个体化治疗提供很大帮助。本课题组前期已成功合成了200nm掺杂金属铁的二氧化硅空心纳米微球（HS-Fe），发现HS-Fe被巨噬细胞吞噬2-5天后即出现HS-Fe纳米微球崩解；另外HS-Fe超声造影信号较强、维持时间较长，且具有US及MRI双模态成像功能，因此本研究拟在已成功制备的可降解HS-Fe的基础上，制备携CD68单抗HS-Fe的US/MRI双模态靶向造影剂，探讨使用该造影剂显示动脉粥样硬化斑块内巨噬细胞富集区的可能性，并观察HS-Fe在体内的代谢情况和生物毒性，从而为不稳定斑块的评估提供一种安全、有效的方法。

Atherosclerosis is one of the leading causes of death and disability in the world. Macrophages recruitment has emerged as the crucial force driving the initiation and progression of atherosclerotic lesion. Therefore, the identification and quantification of macrophages is of vital importance for vulnerable plaque judgement. Ultrasound molecular imaging is developing fast in recent years. Our team has successfully synthesized Fe-doped hollow silica nanospheres（HS-Fe） before, which has strong ultrasound contrast signal which can maintain for a long time, and has US/MRI dual mode imaging function. In addition, HS-Fe was found biodegradable after phagocytosed by macrophage 2-5 days later. On the basis of strong penetrating power as nanospheres, US/MRI dual mode imaging function and biodegradable characteristics of HS-Fe , we intend to prepare CD68 receptor-targeted HS-Fe with the purpose to identify riching macrophages areas in atherosclerotic plaque by dual-modal US/MRI imaging and to explore metabolism and toxicity of HS-Fe in vivo, so as to provide a safe and effective method for the assessment of vulnerable plaque.