基于X射线激发的深部肿瘤光动力学治疗的β-NaGdF4@PEG-P.S.纳米系统的研究

Photodynamic therapy, which is a non-invasive treatment for cancer, has been used in clinic for treating lung cancer, skin cancer et al. successfully since 1980s. However, due to the limitation on tissue penetration of light, it cannot be used for treating cancers located where light cannot be delivered efficiently, directly delivering or with optical fibers. X-ray excited photodynamic therapy (XE-PDT) as a novel deep cancer treatment modality which is using X-ray as the energy source to excite X-ray excited luminescence nanoparticles (XE-NP) to emitting UV-Vis light for activating combined photosensitizer (P.S.) to generate singlet oxygen for treating cancer. Although, the introducing of X-ray as the energy source and XE-NP resolves the light penetration problem, high X-ray dose and the toxicity of XE-NP are still the major challenges for XE-PDT. Here, we propose a novel NaGdF4@PEG-P.S. XE-PDT system with enhanced biosafety, tumor accumulation rate, FRET efficiency, which will make low dose XE-PDT possible for clinic applications. NaGdF4 nanoparticles, with enhanced stability, smaller size, and narrow size distribution, are co-immobilized with PEG and P.S. to achieve good biocompatibility and high singlet oxygen generation efficiency simultaneously. The synthesis of NaGdF4 and doping species need to be studied sufficiently, in order to have high quantum yield rate, perfectly matched spectrum for P.S. and proper size to maximize the EPR efficiency for higher tumor accumulation. The mechanism of PEG and P.S. co-immobilization need to be manipulated to allow NaGdF4@PEG-P.S. system to have good biosafety and high singlet oxygen generation efficiency in this study.

光动力学，由于受到光在体内穿透深度的限制，难以被用于深部肿瘤的治疗。X射线激发光动力（XE-PDT），借助于X射线激发与光敏剂结合的发光纳米材料，从而实现穿透深及准直率高的深部肿瘤治疗，有望成为深部肿瘤的高效无介入治疗方案。但是目前XE-PDT使用的纳米材料形状不规则、粒径不均、尺寸过大及发光效率低，易造成脏器毒性、肿瘤富集率低以及辐射剂量高等弊端。因此，为了实现高效XE-PDT，纳米材料的发光效率、与光敏剂间的能量传递效率以及生物安全性方面的研究就显得至关重要。本项目拟创新的应用β-NaGdF4纳米颗粒作为发光材料基质，重点研究其发光效率、光谱以及尺寸的控制，使其能够高度吻合光敏剂吸收光谱并具有高肿瘤富集率（EPR效应）；并通过对其表面进行聚乙二醇与光敏剂共耦合，使其在保证生物安全性的同时，实现高效的XE-PDT，为XE-PDT应用于临床治疗深部肿瘤奠定坚实的理论与实验基础。

项目预计发表SCI文章2-3篇，实际发表SCI文章5篇，预计申请专利1-2项，实际申请专利2项并通过审核，达成了项目目标。X-PDT目前仍存在着X射线辐射剂量高且纳米耦合体系生物安全性差的问题。本课题研发的具备高发光、粒径均匀且可控的X射线激发发光纳米颗粒，成功通过配体交换（PAA和AEP）或无基团化处理，将纳米颗粒表面的油酸基团进行处理，并通过FT-IR对其表面基团进行鉴定，发现纳米颗粒表面的油酸基团可被成功的置换为PAA、AEP或无基团，从而使纳米颗粒具备良好的水中分散性；再次，将表面修饰后的纳米颗粒与细胞进行共培养，当纳米颗粒浓度高达1 mg/mL的情况下，细胞的存活率依然高于90%以上，从而证明其良好的生物安全性，成功制备3种具备生物安全性的纳米颗粒。通过使用荧光光谱仪对表面修饰后的纳米颗粒进行测定发现，AEP修饰的纳米颗粒发光损失最小，且其表面的氨基基团具备与光敏剂共价耦合的潜能。在纳米粒-光敏剂耦合系统的研发方面，项目成功研发了3种纳米粒-光敏剂耦合系统，并创新性的提出AEP与光敏剂玫瑰红或CE-6的单步耦合法。通过离体与在体肿瘤模型验证，其中NaLuF4: 15% Tb-RB纳米耦合系统在X射线剂量仅为0.19 Gy的条件下，抑瘤率可达80%以上，当剂量为4 Gy时，抑瘤率可达90%以上，为X-PDT向临床应用推进提供了实验及理论依据。