Polymer Program, Institute of Materials Science and Physics Department, University of Connecticut , Storrs, Connecticut 06269, United States.
ACS Nano. 2017 Apr 25;11(4):3651-3661. doi: 10.1021/acsnano.6b08043. Epub 2017 Mar 22.
Gold nanoparticles (AuNPs) exhibit strong fluorescent and electromagnetic properties, which can be enhanced upon clustering and used in therapeutic, imaging, and sensing applications. A combination of gold nanoparticles with lipid nanodiscs can be attractive for AuNP self-assembly and useful in biomedical applications. Using molecular dynamics simulations we show that lipid nanodiscs can serve as templates for AuNP clustering into rings and string-like structures. We demonstrate that equilibrium encapsulation of 1 nm hydrophobically modified AuNPs into lipid nanodiscs composed of a mixture of dipalmitoylphosphatidylcholine (DPPC) and dihexanoylphosphatidylcholine (DHPC) lipids occurs at the rim and results in formation of a ring of gold. The interior of the nanodisc is inaccessible to AuNPs due to the DPPC liquid crystalline order. With temperature increase the lipid order diminishes, initiating the nanodisc transformation into a vesicle, upon which encapsulated AuNPs cluster into a close-packed string or nanoring, thereby stalling the vesiculation process at a "round vase" or cup-like stage depending on the AuNP concentration. In contrast, encapsulation of AuNPs by an equilibrium lipid vesicle results in its deformation with randomly clustered AuNPs, in agreement with experimental observations. We characterize the AuNP cluster size and surface-to-surface pair distribution, both of which impact the AuNP luminescent properties. We investigate the effect of alkane tether length on the nanodisc stability and AuNP clustering inside the nanodiscs and vesicles. Our results show that lipid nanodiscs can enhance gold cluster formation, which can be further exploited in imaging applications.
金纳米粒子（AuNPs）表现出强荧光和电磁性质，这些性质在聚集时可以增强，并用于治疗、成像和传感应用。金纳米粒子与脂质纳米盘的结合对于 AuNP 自组装具有吸引力，并在生物医学应用中很有用。使用分子动力学模拟，我们表明脂质纳米盘可以作为 AuNP 聚集为环和线状结构的模板。我们证明，1nm 疏水性修饰的 AuNPs 在由二棕榈酰磷脂酰胆碱（DPPC）和二己酰基磷脂酰胆碱（DHPC）脂质混合物组成的脂质纳米盘中的平衡包封发生在边缘，并导致金环的形成。由于 DPPC 液晶有序性，纳米盘的内部无法容纳 AuNPs。随着温度升高，脂质有序性减小，纳米盘开始转化为囊泡，在囊泡中，包裹的 AuNPs 聚集形成紧密堆积的串或纳米环，从而根据 AuNP 浓度在“圆花瓶”或杯状阶段停止囊泡化过程。相比之下，AuNP 通过平衡脂质囊泡的包封导致其变形，其中 AuNP 随机聚集，这与实验观察结果一致。我们表征了 AuNP 簇的大小和表面到表面的配对分布，这两者都影响 AuNP 的发光性质。我们研究了烷烃系链长度对纳米盘稳定性和 AuNP 在纳米盘中和囊泡内聚集的影响。我们的结果表明，脂质纳米盘可以增强金簇的形成，这可以进一步用于成像应用。
