分子伞－光敏剂/氧化石墨烯载药体系的制备及其光治疗性能研究

As a rising star in material sciences, two-dimensional (2-D) graphene has many interesting physical and chemical properties that are potentially useful in biological and biomedical applications. Graphene absorbs light in the near-infrared region, and can cause cell death by a localized photothermal or photohyperthermia effect. Using graphene, it would be straightforward to develop innovative multimodal therapies that combine photothermal and photodynamic therapies. However, photosensitizing efficiency of photosensitizers would be drastically reduced due to self-aggregation of photosensitizers and π-π stacking between the photosensitizer and graphene, if the photosensitizers are directly loaded on the graphene. To resolve this problem, we will use molecular umbrella to modify the photosensitizers. In this project the following studies were investigated: (1) Molecular umbrellas with two or more "amphiphilic walls" are synthesized. Then molecular umbrella-photosensitizer conjugates are fabricated by coupling photosensitizer to molecular umbrellas; (2) Functionalized graphene oxide is chosen as carrier for loading molecular umbrella-photosensitizer conjugates. The drug loading ratio, shielding ability, efficiencies of singlet oxygen generation and heat conversion ability of adsorbed light of this system will be determined; (3) Cellular uptake, cytotoxicity and subcellular localization of this system will be investigated in vitro; and (4) Biodistribution, target performance, photodynamic and photothermal efficiency will be estimated in vivo. In addition, necropsy and immunohistochemical analysis will be carried out. The aims of this project are to obtain the preparation method of functional graphene oxide as a nanocarrier for photosensitizers, and provide a double photodynamic therapy and photohyperthermia cancer phototherapy system. It is expected that the results of this project will promote the development of phototherapy system.

本项目拟采用分子伞对光敏剂进行修饰，以功能化氧化石墨烯为载体，构建一种能够集成光动力治疗和光热治疗于一体的新型光治疗的载药体系。本研究主要包括以下四个方面的内容：（1）构建新型的多伞面分子伞，并与光敏剂偶联，获得分子伞－光敏剂共轭物；（2）将分子伞－光敏剂共轭物装载在功能化氧化石墨烯上，获得分子伞－光敏剂/氧化石墨烯载药体系，考察载药性能、屏蔽能力、单线态氧产率和光热转换能力；（3）通过体外实验考察载药体系的穿膜性能、光损伤能力，阐明内化机理，确定亚细胞定位；（4）通过体内实验考察载药体系在体内的组织分布、靶向性能、光动力杀伤及光热损伤效果，并应用病理学及免疫组化法进行观察和评价。预期本项目的研究成果将获得分子伞－光敏剂/氧化石墨烯载药体系的制备方法，提供同时具有光动力治疗和光热治疗的光治疗模式，推动光敏剂载体向多样化、有效化、安全化方向发展，为相关疾病的诊断和治疗提供理论基础和实验数据。

由于大多数的光敏剂呈现强疏水特性，必须在药物载体的协助下才能完成体内运输。此外，这类光敏剂含有平面的、较大的共轭芳香环，在水系溶液中，大环平面间的疏水作用以及分子间较强的π－π作用，常导致光敏剂以聚集态存在，严重降低了光敏化能力。本项目将具有独特“伞”型结构的分子药物载体-分子伞与光敏剂分子偶联，获得了分子伞-光敏剂共轭物。该共轭物可借助于分子伞的屏蔽构象所产生的空间位阻阻碍光敏剂分子形成二聚体或多聚体，显著提高了疏水性光敏剂的光敏化能力。本研究以功能化的氧化石墨烯为载体，构建了分子伞－光敏剂/氧化石墨烯载药体系。该体系不仅可通过氧化石墨烯的近红外区吸光特性实现光热治疗，还可借助于分子伞的屏蔽构象实现光敏剂的光动力活性。本项目重点研究了分子伞-光敏剂共轭物的合成方法，分子伞的屏蔽性能，光敏化能力，体外及体内的光毒性和暗毒性。研究结果表明所构建的分子伞-光敏剂/氧化石墨烯载药体系展现了良好的光动力和光热协同治疗性能，并具有较高的生物安全性。这一研究结果为提升光敏剂的光敏化能力以及构建安全有效的光动-光热联合治疗体系奠定了良好的基础。