基于金纳米粒给药系统的近红外光介导同步光热与光动力治疗基础研究

Photothermal therapy (PTT) is an emerging technique that uses near-infrared (NIR) laser light-generated heat to destroy tumor cells. However, complete tumor eradication by PTT alone is difficult because the distribution of gold nanoparticles in tumors is often uneven, which induces the heterogeneous heat distribution and sublethal thermal dose in some areas of the tumor. Photodynamic therapy (PDT) to treat diseases including cancer is known as a non-invasive medical technology. However, most photosensitizers are excited by visible or even UV light, which has limited penetration depth due to the light absorption and scattering by biological tissues, resulting in ineffective therapeutic effects to internal or large tumors. If the photosensitizers are excited by NIR light, the generated toxicity (reactive oxygen species (ROS) for killing cancer cells) will be very low because the absorption band of the photosensitizers is not in NIR range. Here, we will develop multi-functional due-sensitive gold nanospheres to solve above mentioned problems: Hematophorphyrin Monomethyl Ether (HMME), a photosensitizer with the excitation at 500-600 nm and 600-800 nm, is loaded onto hollow gold nanospheres (HAuNS), which are novel gold nanostructures ideally suited for PTT because of their unique combination of small size (30-50 nm), biocompatibility, and strong and tunable absorption in the entire NIR region. Furthermore, we for the first time use a cyclic peptide TNYLFSPNGPIARAW (designated as TNYL) as a homing ligand to modify the surface HAuNS, which displays high binding affinity to EphB4, overexpressed in numerous tumor types. Finally, TNYL modified HAuNS containing HMME (HMME-tHAuNS), as the duel-sensitive gold nanospheres, was obtained. After the administration of iv injection, HMME-tHAuNS is accumulated in tumors with positive-EphB4 mediated by TNYL peptide. By the local NIR light irradiation in tumors, HMME-tHAuNS displays strong PTA efficacy. Simultaneously, the photothermal effect induces the triggered-release of HMME, and the released HMME can be excited by NIR light (800nm wavelength) and the light of 530 nm wavelength generated by HAuNS due to the NIR light irradiation to present strong PDT efficacy. By the combination of simultaneous PTT and PDT, the cancer cells will be killed with significantly increased possibility, compared with that by PTT or PDT alone. The combination of simultaneous PTT and PDT mediated by our duel-sensitive gold nanospheres will be a very promising method of tumor therapy.

肿瘤的光热治疗和光动力治疗，不受肿瘤基因变异的影响，是肿瘤治疗的重要研究方向之一。受光热治疗肿瘤内部不均匀热量分布，以及光敏剂光源的组织渗透性影响，二种治疗都存在不同程度的缺陷。本项目采用中空金纳米粒包裹光敏剂，新型环形多肽修饰粒子表面，构建一种具有肿瘤靶向性的新型纳米给药系统，在较强组织穿透与扩散性近红外光介导下具备同步光热与光动力治疗功能。工作原理为：通过肿瘤局部的近红外激光照射，纳米粒产生光热治疗作用；同时，光热效应控制光敏分子的释放与肿瘤内扩散，释放的光敏分子受到外界波长800nm近红外光以及载体自身激发出的530nm的双重光波的激发，产生强光动力治疗作用。通过本项目的实施，阐明同步光热与光动力联合治疗的优势与基础理论，为癌症治疗开拓新的思路，有望显著提升癌症的治愈效果。

恶性肿瘤严重威胁人类健康，临床上常规治疗方案仍然达不到理想的治疗效果。光热疗法（photothermal therapy，PTT）以及光动力疗法(photodynamic therapy，PDT)分别通过过高热和活性氧对肿瘤产生特异性杀伤作用，疗效确切，副作用极小。然而PTT作用不均，组织缺氧和PDT耐药，单一PTT和PDT治疗均存在局限性，两者联合可发挥更强及协同作用。近红外光组织穿透强，是PTT和PDT较理想光源。然而近红外PDT光敏剂发展较为滞后，近红外光介导同步PTT和PDT的研究较少。同时，PDT光敏剂与PTT材料结合时易于光淬灭，导致PDT效能下降，这与两者间距相关。.本项目中，我们构建了基于中空金纳米球（hollow gold nanospheres，HAuNS）的新型同步光热光动力治疗系统。采用适当分子量聚乙烯亚胺（Polyethylenimine，PEI）修饰并扩展HAuNS表面，控制结合近红外光敏剂吲哚菁绿（Indocyanine Green，ICG）与HAuNS距离，维持了ICG荧光及HAuNS空间稳定性。结果显示该系统（ICG-PEI-HAuNS）体内外表现出增强的光热效应和活性氧产率，对肿瘤生长与转移均呈现有效抑制作用。进一步采用EphB4受体具有特异性亲和力的靶向多肽TNYL修饰粒子表面，形成主动靶向纳米球（TNYL-ICG-HAuNS），验证其特异性摄取及同步光热光动力杀伤作用。并发现转录因子Nrf2的表达将引起一系列与细胞氧化应激相关蛋白（如ABCG2，NQO-1和HIF-1α）表达上调，引起对ICG光动力疗效耐受，而对TNYL-ICG-HAuNS无影响，显示其具有逃逸光动力耐药蛋白识别和清除能力。.通过该项目实施，共发表SCI论文12篇，发表在Small、J controlled release、ACS Appl. Mater. Interfaces、Biomaterials、Nanoscale、Part Fibre Toxicol等，总影响因子92.48，篇均7.71。获中国发明专利授权2 项，申请专利2项。培养硕士和博士研究生各3人。本研究证明了相比单一PTT或PDT，近红外光介导同步光热光动力治疗系统在抗肿瘤生长以及转移方面存在显著优势，且能克服光动力治疗耐受性，填补了该领域研究空白，有望成为一种新型实效的肿瘤联合治疗方法。