低毒近红外Ag2S量子点探针构建及其在肿瘤检测中应用

Quantum dots (QDs) is a novel kind of fluorescent nanomaterial, and the QDs-based bioprobes are well-suited for the applications of biomedical detection due to their superior optical features and versatile surface chemistry. Near-infrared (NIR) fluorescent QDs exhibit special superiority for the study of nanodiagnostics and in vivo imaging, because the NIR QDs fluorescence could penetrate deeply into the body and autofluorescence background is weak in the NIR region. However, the traditional NIR QDs based probes suffer from disadvantages, including cytotoxicity, low photoluminescence (PL) quantum yield (QY), weak stability and poor targeting ability. Therefore, in this proposal, novel low toxicity NIR Ag2S QDs with different sizes and surface structures will be selected, and the QY and stability will be improved by coating ZnS shell on the Ag2S QDs. The Ag2S QDs-based tumor targeting bioprobe will be fabricated through the surface modification and bio-functionalization process, and will be applied to in vivo tumor diagnosis of nude mice with high sensitivity and selectivity. The cytotoxicity and the targeting ability will be investigated. The research will provide a novel simple and reliable technique for the study and clinical diagnosis of tumor.

量子点是一种新型的荧光纳米材料，具有优异的光学性能及丰富的表面化学性质，在生物医学检测领域具有较好应用前景。近红外量子点应用于生物成像时背景干扰小、穿透深度大，在生物医学检测方面更具有优势。然而，传统近红外量子点生物探针面临许多问题，包括细胞毒性大、荧光量子产率低、稳定性差以及靶向性差等问题。基于此，本课题拟以不含有毒元素的新型低毒、近红外发光Ag2S量子点为研究对象，通过包覆ZnS壳层的方法，提高Ag2S量子点荧光量子产率及稳定性；通过表面修饰及生物功能化，偶联靶向分子，构建量子点生物探针；通过肿瘤细胞成像及细胞毒性实验，考察探针的靶向性和毒性；通过小鼠活体肿瘤成像研究，建立基于该探针的、高灵敏的、特异性的、活体肿瘤诊断技术，为肿瘤学基础研究和肿瘤临床诊断，提供简便、快捷、可靠的新技术和新方法。

本项目主要围绕I-VI族Ag2S量子点的可控制备及纳米生物探针的构建开展研究，解决传统近红外量子点细胞毒性大、荧光量子产率低及稳定性差等问题。设计和可控制备了性能稳定的低毒性近红外Ag2S量子点，系统研究了合成过程中晶体形成规律，解决了难以在小尺寸范围可控制备I-VI族Ag2S量子点的难题；发展了ZnS包覆Ag2S量子点的合成方法，成功制备了“核/壳”型Ag2S/ZnS量子点，提高了Ag2S量子点的稳定性；发展了一种温和的、无需高温、无需复杂除氧流程的水相合成新策略，成功得到水溶性Ag2S量子点；系统研究了不同合成体系所得Ag2S量子点的生物毒性，证实Ag2S量子点比传统含Cd、含Pb量子点具有更好的生物相容性，通过小鼠活体成像实验，验证了Ag2S量子点在肿瘤检测应用的潜力；利用Cu2+离子对Ag2S量子点的荧光猝灭，构建了基于Ag2S量子点的高灵敏、高选择性Cu2+离子检测探针，并结合荧光寿命和等温滴定量热(ITC)等多种手段，研究了Ag2S量子点与Cu2+的相互作用机理。