We report an experimental study of the structure of polymer-capped gold nanorods (AuNRs) binding to model phospholipid monolayers to elucidate the mechanism that drives the insertion of the AuNRs into phospholipid membranes. The experimental system consists of four different cases of AuNRs interacting with lipid monolayers: cationic and anionic polymer-capped AuNRs suspended in the pure water subphase of Langmuir monolayers of zwitterionic and anionic phospholipids, separately. Liquid surface x-ray reflectivity was used to measure in situ the structure of the lipids and AuNRs at the air-water interface with sub-nanometer resolution, yielding quantitatively the amount, orientation, as well as depth of AuNR insertion into the monolayer. In the case of a zwitterionic monolayer composed of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine, cationic Poly-diallyldimethylammonium chloride (PDC) capped AuNRs (PDC-AuNRs) adsorbed peripherally at the water-lipid interface whereas the anionic Poly-sodium 4-styrenesulfonate (PSS) capped AuNRs (PSS-AuNRs) penetrated deeply into the lipid monolayer. In the case of an anionic monolayer composed of 1-stearoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (SOPG), PDC-AuNRs inserted into the monolayer whereas PSS-AuNRs were not even attracted to the monolayer. The results suggest that the adsorption process of AuNRs to model membranes may proceed through different mechanisms. In the presence of a charged membrane, electrostatic interactions drove the AuNRs to or away from the membrane depending on the nature of the charge of the lipid film and the AuNRs, while in the presence of a zwitterionic membrane, both electrostatic interactions and hydrophobic interactions mediated the insertion of the AuNRs into the membrane.

我们报告了聚合物封端的金纳米棒 (AuNRs) 结构与模型磷脂单层结合的实验研究，以阐明驱动 AuNRs 插入磷脂膜的机制。实验系统由四种不同的 AuNR 与脂质单层相互作用的情况组成：分别悬浮在两性离子和阴离子磷脂的朗缪尔单层的纯水亚相中的阳离子和阴离子聚合物封端的 AuNR。液体表面 X 射线反射率用于以亚纳米分辨率原位测量空气 - 水界面处的脂质和 AuNR 的结构，定量产生 AuNR 插入单层的数量、方向和深度。在由 1-硬脂酰-2-油酰-组成的两性离子单层的情况下sn-甘油-3-磷酸胆碱、阳离子聚二烯丙基二甲基氯化铵 (PDC) 封端的 AuNRs (PDC-AuNRs) 吸附在水-脂质界面的外围，而阴离子聚 ​​4-苯乙烯磺酸钠 (PSS) 封端的 AuNRs (PSS-AuNRs)深入渗透到脂质单层中。对于由 1-硬脂酰-2-油酰-sn-甘油-3-磷酸-(1'- rac-glycerol) (SOPG)，PDC-AuNRs 插入单层，而 PSS-AuNRs 甚至没有被吸引到单层上。结果表明，AuNRs 对模型膜的吸附过程可能通过不同的机制进行。在带电膜的存在下，静电相互作用驱使 AuNRs 进入或远离膜，这取决于脂质膜和 AuNRs 的电荷性质，而在两性离子膜的存在下，静电相互作用和疏水相互作用都介导将 AuNRs 插入到膜中。