诊疗一体化近红外荧光探针的构建及其用于缺血性脑卒中的可视化精准治疗

Due to its high morbidity, mortality and disability, Cerebral Ischemic Stroke (CIS) is detrimental to human life. When CIS occurs, cerebral neurocytes are damaged irreversible because of no effective theranostic method. To overcome the late diagnosis and lack of immediate treatment, we develop a theranostic probe for near-infrared (NIR) fluorescence imaging and precise therapy of CIS. In this structure, the NIR group azo-BODIPY is connected to the antioxidant-Melatonin through the ROS sensitive bond TK, then reacted to SHp peptide which has high affinity with glutamate receptors specifically expressed in injured neurons. As a response to high reactive oxygen species (ROS), the probe is decomposed into azo-BODIPY and melatonin. The azo-BODIPY emits in NIR field and can be used as fluorescent imaging agent for the detection of injured brain tissues. Meanwhile, the released melatonin can be served as a drug for repairing the damaged neutral tissues, depending on its ROS level. As a result, this strategy may provide a safe and efficient way for diagnosis and therapy of CIS.

缺血性脑卒中（CIS）具有高发病率、高致死率、高致残率等特点，严重危害人类健康。疾病发生时，受限于当前诊断技术的缺陷和后续治疗的不及时，造成脑组织神经细胞不可逆的、永久性的损伤。因此，为了实现对CIS的早期诊断和精准治疗，本课题拟开发一种对脑组织损伤细胞具有特异性识别能力的诊疗一体化近红外荧光探针SHp-IR-BTM：近红外荧光基团azo-BODIPY通过ROS响应性连接剂TK与抗氧化剂褪黑素和对损伤神经细胞特异性表达的谷氨酸盐受体具有高亲和力的SHp肽相连。该诊疗探针在氧化应激损伤神经细胞内高水平ROS作用下，响应性分解生成azo-BODIPY，产生近红外荧光，利用对荧光信号的高灵敏检测实现对脑损伤神经细胞的精确诊断和示踪；同时，根据疾病严重程度（ROS水平），释放相应当量的褪黑素，有效保护神经细胞，实现疾病的精准治疗，为建立安全、高效的CIS诊疗一体化新方案提供直接科学依据。

缺血性脑卒中病理生理机制存在损伤级联反应，其中氧化应激及其所诱导的细胞凋亡会导致继发性脑损伤。本项目以对损伤神经细胞特异性表达的谷氨酸盐受体具有高亲和力的SHp肽为靶向基团，构建活性氧（ROS）响应性小分子近红外荧光探针，该探针对神经细胞内具有良好的靶向性和ROS响应性，由于其无法穿透血脑屏障限制了其动物体内诊疗效果。在本项目的资助下，进一步开展“细胞器靶向光敏剂及其光动力治疗（PDT）应用”研究，传统光敏剂存在活性氧产生不足、亚细胞器靶向特异性差等缺点，从而影响其PDT效果。因此，课题组开发了两种基于聚集诱导发光（AIE）性能的亚细胞器（线粒体、溶酶体）靶向荧光探针，系统考察了探针的光物理性能，理论计算证明其ROS产生效率。细胞和动物实验表明两种探针都具有较高的光稳定性、优异的细胞器靶向特异性和良好的光动力治疗效果，为此类光敏剂的发展起到了一定的推动作用。