增强滞留型AIE多功能分子探针的构建及在乳腺癌手术导航和光动力治疗中的应用研究

Intraoperative precise resection of early breast cancer plays an important role in reducing tumor recurrence rate and increasing the breast-conserving rate in women. In order to meet the needs of intraoperative navigation system for ultra-high signal-to-noise ratio and long-term stable imaging, this project intends to use the self-assembling peptides, aggregation-induced emission (AIE) molecule and fluorescent quencher to prepare near-infrared small molecule fluorescence turn-on probe with enhanced retention property. After the probe is cleaved by matrix metalloproteinase-2, which is highly expressed in the tumor microenvironment, the quencher linked to the hydrophilic amino acid sequence rapidly leaves, and the self-assembly of the peptide induces the transition of the probe from small molecule to nano-aggregate, causing the AIE molecule to emit strong fluorescence. The nano-aggregate will be efficiently retained in the tumor site to provide long-term stable imaging. In addition, for residual tumors that can't be completely removed by palliative surgery, the prepared AIE probe can generate singlet oxygen while fluorescence activation for photodynamic therapy of residual tumors. Using the strategy of combination of peptide response self-assembly and AIE molecule, we will systematically investigate the effects of different amounts of phenylalanine (F) and capping groups on the morphology and size of probe aggregation, as well as the fluorescence signal-to-noise ratio and assembly of the probe at the tumor site, with a view to providing a new idea and strategy for the development of intelligent imaging probes for surgical navigation and photodynamic therapy.

早期乳腺癌的术中精准切除对于降低肿瘤复发率、增加女性保乳率方面有重要作用。为满足术中导航系统对超高信噪比和长时间稳定成像的需求，本项目拟利用自组装多肽、聚集诱导发光（AIE）分子和荧光淬灭剂，制备增强滞留型近红外小分子荧光开启探针。探针经肿瘤微环境高表达的MMP-2切割后，连接亲水氨基酸序列的淬灭剂快速离去，多肽自组装诱发探针由小分子向纳米聚集体转变，促使AIE分子发出强烈荧光，并高效滞留在肿瘤部位，提供长时间稳定成像。此外，对姑息性手术无法完全切除的残余肿瘤，制备的AIE探针，可在荧光激活的同时产生单线态氧，对其进行光动力治疗。通过本项目提出的多肽响应自组装和AIE相结合的策略，系统考察不同苯丙氨酸数量和封端基团对探针聚集形态和尺寸的影响，以及探针在肿瘤部位荧光信噪比和组装滞留程度，以期为开发用于手术导航和光动力治疗智能影像探针提供新的思路和策略。

目前，手术切除仍是治疗乳腺癌的重要手段。为此，开发针对乳腺癌高表达酶响应的荧光开启探针对于精准识别微小肿瘤和指导其切除具有重要意义。在本项目中，我们构建了一种弗林酶响应的聚集诱导发光AIE荧光开启探针，并对其弗林酶响应效率、响应特异性、抗干扰能力和细胞相容性等特性进行了表征。结果显示，在探针中引入荧光淬灭剂，并与聚谷氨酸共组装可以提高探针信噪比，降低其光毒性和溶血率，进而提高其细胞相容性。体内外结果显示，该探针可以点亮高表达弗林酶的乳腺癌细胞和微小肿瘤，并可用来以较高准确率指导肿瘤手术切除。此外，我们还构建出一种碱性磷酸酶响应的AIE荧光和活性氧ROS双开启探针。该探针经碱性磷酸酶脱除磷酸基团后，形成纳米组装体并倾向于富集在癌细胞溶酶体中，并通过增加溶酶体膜通透性来诱导免疫原性细胞死亡，并可将免疫“冷”肿瘤变“热”，结合光动力治疗可促进上述过程。该研究在溶酶体相关死亡和免疫治疗间建立桥梁。与此同时，我们还构建出一种谷胱甘肽响应后可进行共价组装的AIE探针。综上所述，该项目通过借助非共价和共价组装体系，并合理选择和调控酶切多肽片段，构建出多种具有良好生物相容性和高信噪比的探针，并应用在荧光成像指导的肿瘤手术、光动力治疗和肿瘤标志物检测方面，对于AIE探针在生物成像领域的发展具有推动意义。