以NGR为智能载体的APN/CD13靶向近红外荧光探针的研究

With the development of precision medicine technology, the key technique of molecular imaging surgical navigation is the fluorescent probe, which is not only tumor targeting, but also capable of precise expressing the tumor and its border. In the view of the emergence and development of over-expressing of aminopeptidase N (APN/CD13) in tumor, with the aid of “off-on” mechanism of fluorescent probes and the design principle of targeted drugs, this project will focus on the design, synthesis and biological evaluation of a new series of tumor targeting and biodegradable near-infrared fluorescent APN/CD13 probes based on intelligent polypeptide NGR. Using dicyanomethylene-4H-pyran (DCM) fluorophore intends to perform stable, real-time and online fluorescence imaging of probe; with the aid of NGR targeting, the location of tumor can be precise expressed; fluorophore can be activated and release strong fluorescent signal only when disulfide bonds in the probe are in situ cut off, precision locating and elaborate expression of the tumor and its border can be realized. Through interdisciplinary integration, this project is to study intelligent near-infrared fluorescent probes with tumor targeting and precise expressing the tumor and its border, to select the candidate compounds for clinical fluorescent imaging surgical navigation system, and to provide new ideas and new strategies for the prevention, diagnosis and treatment of the tumor.

随着精准医学技术的发展，具备靶向定位和精准表达肿瘤组织边界的荧光探针是手术导航用分子影像技术的关键。针对氨肽酶N（APN/CD13）高表达肿瘤组织的发生和发展，借助荧光探针“关-开”机制及靶向性药物的设计原理，本项目拟通过设计、合成以多肽（NGR）为智能载体、二硫键连接的APN/CD13靶向可生物降解的近红外荧光探针。采用可生物降解连接臂，提高荧光探针的生物相容性和构象稳定性；采用吡喃腈（DCM）类近红外荧光团，实现探针稳定、实时、在线荧光成像；借助NGR的靶向性，精准定位肿瘤组织位置，采用探针分子的二硫键肿瘤细胞内环境原位切断，激活荧光团并释放强烈荧光信号，实现肿瘤及其边缘的精准定位和精细表达。本项目通过学科交叉融合，开展具有肿瘤组织靶向表达和边界清晰化定位性能的智能型近红外荧光探针的研究，为临床恶性肿瘤手术切除提供精准导航分子影像探针，为肿瘤的预防、诊断及治疗提供新的思路和新的策略。

由于荧光探针具有高选择性、高灵敏度、分析迅速、操作简单且可实现生物成像等优点得到广泛的应用，本项目根据大量的文献调研和初步的理论计算结果，设计了基于不同识别机理的化学传感器，实现了对目标分子（离子）的高选择性、高灵敏度的识别，在此基础上将其应用于环境和活体细胞的成像。本项目不仅通过实验结果和理论计算阐明了识别作用的发光机制，而且拓展了荧光探针的类型，对专一性识别目标分子或离子提供了新的思路和方法。