过氧化氢“激活”型纳米探针的原位构建及用于乳腺癌光声诊断的研究

Breast carcinoma is a malignant disease which seriously threats female health. Accurate diagnosis of breast cancer and differential diagnosis between benign and malignant are the key to improve the cure rate of breast carcinoma and survival quality of the patients. At present, there are some deficiencies in the diagnosis of breast carcinoma. Previous studies have found that in situ construction of contrast agent has the characteristics of low signal-to-noise, low attenuation, high sensitivity and specificity, which can improve the diagnostic effect of breast cancer. In view of this characteristic, this project intends to construct an in situ gold nano-smart photoacoustic probe with endogenous hydrogen peroxide response for the diagnosis of breast carcinoma. The structure and related properties of the probe were evaluated in vitro and applied to animal models of breast carcinoma. In vivo experiments show that the smart photoacoustic probe can effectively improve the diagnosis of breast carcinoma. The nanoprobe precursors constructed in this project can only be reduced to elemental gold in malignant tumor cells with high expression of hydrogen peroxide and produce signal changes, while no signal changes in normal cells and benign tissues, so as to realize the specific identification of malignant breast carcinoma. The successful implementation of this study will establish a new method for the specific diagnosis of malignant breast carcinoma and provide a new idea for molecular imaging research.

乳腺癌严重威胁女性生命健康。乳腺癌的准确诊断和良、恶性鉴别是提高乳腺癌治愈率和改善患者生存质量的关键。目前乳腺癌诊断方法存在一定的不足。前期研究发现原位构建对比剂，具有信噪低、不易衰减，高敏感性和特异性的特点，可提高乳腺癌诊断效果。针对这一特性，本项目拟原位构建一种肿瘤内源性过氧化氢响应的金纳米光声探针用于乳腺癌的诊断。体外评价探针结构及相关性能，并将其应用于乳腺癌动物模型。体内实验证明该智能光声探针能有效的提高对乳腺癌的诊断。本项目构建的纳米探针前驱体仅能在过氧化氢高表达的恶性肿瘤细胞被还原成单质金，产生信号改变，而在正常细胞及良性组织不会产生信号变化，实现对乳腺癌恶性肿瘤的特异性鉴别。本研究的顺利实施，将建立特异诊断恶性乳腺癌的新方法，并为分子影像学研究提供全新思路。

随着纳米技术的发展，兼具光学成像高对比度和声学成像中深穿透特性和高分辨率等优点的光声成像技术，是近年来发展最迅速的生物医学诊疗技术，对乳腺癌的早期发现与诊断有重要意义。现有光声探针存在一定的不足。原位构建对比剂，具有信噪低、不易衰减，高敏感性和特异性的特点，可提高乳腺癌诊断效果。研究显示乳腺癌肿瘤细胞内源性过氧化氢的浓度为50~100 μM，远高于正常组织。针对这一特性，本项目原位构建了肿瘤内源性过氧化氢响应的金纳米光声探针用于乳腺癌的诊断。本项目首先体外构建了金纳米光声探针并对其进行表征，然后体外评价了金纳米光声探针的响应性，最后构建小鼠乳腺癌肿瘤模型进行光声成像的活体研究。我们分别在正常肌肉组织和肿瘤组织处注射金纳米探针，然后选择在不同时间点进行光声成像。实验结果显示，肿瘤组织处光声信号强度不断增加而肌肉组织处光声信号几乎不发生改变，证明了该金纳米粒光声探针对肿瘤微环境的响应性。为进一步明确该变化由过氧化氢引起，通过分别给小鼠服用β-异硫氰酸苯乙酯和二甲基硫脲来调节肿瘤微环境中过氧化氢水平。实验结果显示，与对照组相比，小鼠服用β-异硫氰酸苯乙酯后光声信号明显增强，而服用二甲基硫脲的小鼠，光声信号显著降低。这一研究进一步明确了金纳米光声探针对过氧化氢的响应性。本项目构建的纳米探针仅能在过氧化氢高表达的恶性肿瘤细胞产生光声信号改变，一旦探测到信号变化即可反映肿瘤的恶性生物学行为，具有高敏感性和特异性。本项目金纳米光声探针的构建，有望实现乳腺癌的安全、高效、精准诊断，将为乳腺癌的临床诊断提供一种全新的光声对比剂。