肿瘤乏氧分子影像探针的构建及活体成像研究

Hypoxia as one of the key abnormal factors in malignant tumor, is closely related to tumor invasion, metastasis, and drug resistance. Clinical studies have demonstrated that low oxygen tension in tumors is found to be strongly correlated with increased metastasis, poor patient survival as well as drug resistance. Therefore, hypoxia detection is mandatory for deciding clinical treatment and evaluating drug resistance and prognosis, however, it still remains challenging to detect hypoxia in a secure and non-invasive mode. In this proposal, we will use oxygen-sensitive luminescent iridium-complex as hypoxia detection signal vehicle, upconversion nanoparticles with high tissue penetration depth and high resistance to photobleaching as internal reference, to construct the targeted probe for tumor hypoxia quantitative detection. The following research contents are proposed: prepare upconversion nanoparticles with high luminescence intensity by combining hetero-valence cation doping and the buildup of core/shell architecture, synthesis oxygen-sensitive luminescent iridium-complex and tune the optical property, develop the strategy of biocompatible modification of nanoparticles and preparation of the probe, invisgate in vivo quantitive optical hypoxia imaging during tumor progression and intervention therapy. This proposal will develop an in vivo tumor hypoxia senstive detection method.

乏氧是恶性肿瘤的重要特征之一，与肿瘤的侵袭、转移、耐药密切相关。大量临床研究表明肿瘤乏氧与抗肿瘤药物耐受及患者不良预后相关，因此乏氧检测有助于肿瘤临床诊疗方案的确立、耐药及预后评估，然而以安全无创方法对乏氧的定量检测仍面临挑战。本项目提出利用过渡金属复合物发光性质对氧气的高敏感性，以穿透深度深、抗光漂白性质强的稀土上转换发光作为内标，构建靶向肿瘤乏氧检测的光学探针，利用二者的比例发光建立肿瘤乏氧的活体影像学定量检测方法。相关内容包括：拟结合异价掺杂及构建核壳结构方式制备具有高发光效率上转换纳米颗粒；制备氧敏感的过渡金属复合物发光分子并调控其发光性质；发展纳米颗粒表面生物相容性修饰方法及与O2敏感发光分子和靶向分子耦联策略；开展肿瘤及干预中乏氧状态在体成像及定量解析研究，建立安全无创的乏氧在体灵敏检测方法。

肿瘤内乏氧分布的高灵敏度成像和定量解析是本项目的核心内容。乏氧是肿瘤微环境的重要特征之一。肿瘤的乏氧环境不仅会改变调节转录因子的表达水平，从而调节肿瘤的生物学行为，而且乏氧在肿瘤对化疗和放疗的抵抗中起着非常重要的作用。因此，检测肿瘤细胞中的氧含量对于更好地了解肿瘤病理生理学和确定治疗策略至关重要。本项目针对这一需求，深入研究了高灵敏活体肿瘤乏氧检测探针，并发展了肿瘤内乏氧分布的定量解析方法，取得了如下成果：发展了高质量生物相容性稀土发光纳米颗粒的制备方法，揭示了异质掺杂离子和晶体结构对稀土纳米颗粒发光性质的影响和调控机制；制备了基于金属铱Ir（III）配合物的氧敏感响应分子，并结合纳米颗粒表面生物相容性修饰策略，通过共价偶联方式构建了以穿透深度深、抗光漂白性质强的稀土上转换发光颗粒作为内标的靶向肿瘤乏氧检测的光学探针，实现肿瘤乏氧区域的检测；为了进一步提高肿瘤乏氧检测的敏感性，通过将Ir-配合物装载在环糊精分子中提高乏氧检测分子的水溶性，并利用近红外染料Cy7替代纳米颗粒作为内标分子，成功实现活体肿瘤乏氧的在体检测，并通过计算处理绘制出皮下组织和肿瘤区域的乏氧分布图，定量揭示了肿瘤内的乏氧情况；进一步在乏氧检测探针上修饰pH敏感染料或磷脂酰丝氨酸（PS），成功实现肿瘤微环境乏氧和pH的同时检测以及细胞早期凋亡的识别。上述探针的构建对于准确评估恶性肿瘤行为，制定个体化治疗方案具有重要的指导意义。项目相关研究成果在Angew. Chem. Int. Ed、Adv. Sci.、Biomater Sci、Small、frontiers in Chemistry、Journal of Materials Chemistry B等期刊发表文章11篇，培养博士生5名。