肿瘤微血管与实体瘤双靶向型超声激发TiO2基-MRI增强复合剂及其声动力治疗与可视化研究

Titanium dioxide (TiO2) nanoparticles, apart from used as inorganic photosensitizers, under the ultrasonic excitation and sonodynamic therapy are able to be used for inorganic sonosensitizers. Compared with the common organic sonosensitizers, properties of TiO2-based nanoparticles are with the advantages of stable, non-toxic and long retention time in vivo which has potential applications in sonodynamic therapy of malignant tumors (SDT). In addition, ultrasonic excitation of TiO2 overcomes photodynamic therapy of TiO2 usually UV light excitation, and weak penetration and damaging normal tissue for ultraviolet light. This project designs and prepares ultrasound excitation of RGD peptide and folic acid (FA) double targeting breast cancer entity tumor and around micro-environment of sound sensitivity-MRI enhanced TiO2-based nanocomposite materials (RGD-Fe3O4-TiO2-FA Nanocomposite). In this nanocomposite, sound sensitivity nature under ultrasonic excitation based on TiO2 component, MRI contrast enhanced nature based on Fe3O4 component and dual targeting capabilities based on RGD peptides and FA are used for targeting tumor SDT and visualization of SDT efficacy. Human mammary epithelial cells (HMMEC), human breast cancer cell MCF-7 and the breast cancer Dutch tumor model in mouse are used for studying of possibility and stability in dual targeting tumor with SDT effect. A quantitatively characterization method between the uptaken of nanocomposites by cancer cells and the sensitivity of MRI enhanced performance and the efficiency of SDT will be built based on hard X-ray fluorescent microscope technique in Shanghai Synchrotron Radiation Facility. At the aid of MRI enhanced visual capability, the effect of SDT in the breast cancer Dutch tumor model in mouse will be monitored. The mechanism of SDT in the breast cancer Dutch tumor model in mouse will be clarified to provide a basis for the applications of nanocomposites in clinic later.

纳米二氧化钛(TiO2)除用作光敏剂外，还可用作声敏剂实现声动力治疗效果。TiO2基声敏剂具有稳定、无毒及体内维持时间长等优点，且因超声波激发克服了光动力治疗中需紫外光激发，及紫外光穿透性差并对正常组织易产生损伤等不足，在恶性肿瘤的声动力治疗(SDT)中应用潜力巨大。本项目设计并制备超声激发的RGD肽与叶酸偶联的双靶向乳腺癌实体瘤及其周围微环境的TiO2基声敏MRI增强复合试剂，利用TiO2组分的声敏性质，实现SDT功能，利用Fe3O4组分的MRI造影性能，对SDT功效进行可视化追踪。以人乳腺微血管内皮HMMEC细胞、人乳腺癌MCF-7细胞及乳腺癌荷瘤小鼠为对象，研究双重靶向复合试剂的SDT特性；利用上海光源X射线荧光成像技术，构建复合试剂被细胞摄取剂量与SDT功效的可视化定量表征方法；并借助MRI造影诊断技术监测荷瘤小鼠的SDT功效，阐明其原理，为该复合剂在临床治疗中的应用提供依据。

传统乳腺癌诊治方法存在灵敏度低、副作用大的问题，无法实现对乳腺癌的早期诊断与有效治疗。本项目以乳腺癌的精准诊断与可视化有效治疗为目标，设计并构建出一系列基于TiO2、Fe3O4的低毒、高效乳腺癌诊疗纳米探针：黑TiO2纳米探针、黑TiO2-Fe3O4复合纳米探针、黑TiO2-mSiO2核壳纳米探针、白TiO2基-上转换药物载体、白TiO2基-上转换复合纳米探针以及pH敏感的木马靶向Fe3O4纳米探针。本项目主要研究内容包括：1）黑TiO2纳米探针近红外光热治疗乳腺癌；2）黑TiO2-Fe3O4 复合纳米探针MRI可视化光热治疗乳腺癌；3）黑TiO2-mSiO2核壳纳米探针乳腺癌光热治疗与药物控释; 5）白TiO2基-上转换复合纳米探针近红外光动力治疗与化疗协同克服耐药乳腺癌；6）白TiO2基-上转换复合纳米探针乳腺癌的MRI诊断和近红外光动力治疗；7）木马靶向策略下的Fe3O4纳米探针乳腺癌MRI精准成像。本项目解决了两个关键科学问题：1）传统白TiO2需要紫外光激发实现治疗功能，本项目通过更安全、组织穿透更深的近红外光激发实现其治疗功能，2）大幅度地降低了正常组织对纳米粒子非特异性摄取，使得纳米探针对乳腺癌的递送更加高效。通过本项目的实施，在基于TiO2与Fe3O4纳米探针的乳腺癌精准诊断与可视化有效治疗方面取得了一系列有益的成果，为相关纳米探针的进一步临床应用奠定了基础。此外，依托本项目，申请人利用上海同步辐射光源硬X射线荧光显微镜发展了细胞摄取纳米粒子的定性、定量分析方法，为纳米探针的细胞与组织内可视化定量研究奠定了方法学基础。本项目发表SCI学术论文19篇，出版英文专著1本，申请中国发明专利3项,已获授权2项，培养硕士研究生2名。依托本项目获得广东省-基金委超算联合基金1项，并竞争性滚动进入最后的第四轮（54/500+，700万核时，合计168万元）。本项目的部分研究成果荣获2016年宁波市科学技术进步奖一等奖(申请人为第一获奖人, 1/7)，获奖项目名称：肿瘤可视化诊疗分子探针材料 (项目编号: 16160)。