微环境下膜力学性质调控的金纳米棒吸附及内化动力学

A comprehensive understanding of the interaction mechanism between nanomaterials and cell membranes is critical to the researches in the endocytosis mechanism and toxicity control. The accurate target, low toxicity, and environmental responsibility, required by the individuation disease diagnosis and treatment, create new challenges for the biomedical carrier design. We will employ total internal reflection fluorescence microscope, fluorescence tracking, electron microscope, and simulation and theoretical methods, to investigate the synergistic effect of membrane tension and component on the interaction between unspecific/specific-ligand-modified gold nanorods and biomembranes under specific local environment. We will try to build the connections between nanoparticle endocytosis and the density, rigidity of the extracellular matrix as well as the shape of the particles. The nanorod partitioning, aggregation, and membrane shape transition caused by the nanorod-membrane interaction will be obtained, which may be understood from the cooperation among membrane tension, line tension, interlayer coupling, intralayer coupling, and lipid diffusion. Combining the experimental and simulation results, we will employ the Helfrich theory to study the physical mechanisms underlying the confined diffusion, the low surface tension induced vertical insertion, and selective partitioning of nanorods from the competition of the adhesion, bending, and membrane tension energy. The successful completion of the project will deepen the understanding of specific rod-shape viral infection. And it will also provide guidelines for the individuation design of the low toxicity, accurate target, and environmental responsibility nanomaterials.

理解纳米颗粒与生物膜的相互作用是弄清颗粒内吞机制和毒性成因的关键环节。个性化疾病诊断与治疗中高精准靶向、低毒性、环境响应性等要求为纳米载药体系的设计提出了新的挑战。本项目主要选择非/特异性金纳米棒和细胞膜作为研究对象，采用全内反射显微镜、荧光跟踪和电镜等技术，结合模拟和理论方法，研究微环境下，在膜张力与膜组分协同控制下纳米棒与生物膜相互作用的机制。力图获取微环境下，纳米颗粒内吞的细胞外基质密度和硬度及纳米形状依赖性；获得膜张力/线张力、层间耦合-层内耦合/磷脂膜流动性等协同作用下，生物膜表面纳米棒的选择性吸附、聚集、膜形变动力学规律。结合实验和模拟结果，从Helfrich理论角度理解新现象，探索在粘滞力、弹性能和膜张力等竞争下，纳米棒受限取向扩散、低膜张力垂直插膜和选择性吸附等内在的物理机制。项目实施，将对理解特异性棒状病毒感染机理、设计个性化低毒性、高精准响应性靶向材料提供有意义的参考。

本项目基于理论模拟与实验结合研究了微环境下膜力学性质调控的金纳米棒吸附及内化动力学。首先，发现负电性非球形颗粒内吞中的“类电荷吸引”效应，静电排斥的颗粒以高曲率微区攻击接触细胞膜，并诱导带电膜组分的再分布。报道了表面亲疏水修饰影响的纳米颗粒蛋白冠组成，表面羟基化造成载脂蛋白的强吸附且维持原二级结构，提高了颗粒的体循环时间与肿瘤富集。开发了保护性配体促进的肿瘤细胞靶向策略，给出了保护性配体链长、结合能等物理性质对正常、肿瘤细胞摄入差异性的影响。研究了中性粒细胞膜包覆产生的炎症靶向性，表面粘附与信号转导蛋白诱导了颗粒在炎症病灶的富集。设计了金银纳米棒-脂质复合纳米颗粒，肿瘤富过氧化氢微环境触发实现作用的靶向性。通过纳米颗粒间的连接聚合链刚性、长度、疏水性等调控了细胞摄入，考察了颗粒摄入中的协同效应。发现聚合物胶束渗透、融合及包裹进入细胞膜的途径，由配体作用、疏水性、带电性等因素决定。其次，基于分子力学/泊松-玻尔兹曼表面积评估了配体-受体结合能。通过DNA四面体角接枝提高配体-受体亲和性、细胞膜接枝改善受体流动性、动态可逆免疫亲和微界面促进碰撞捕获、聚合物修饰界面调控正常/肿瘤细胞选择性等策略，提升了循环肿瘤细胞检测的精度。并根据国内外研究的最新进展，探索了纳米材料在能量输入的仿生微环境下的非平衡组装机理。研究结果将为纳米材料在生物医学治疗与检测中的深入应用提供启示与指导。