School of Engineering, Center for Biomedical Engineering, Institute for Molecular and Nanoscale Innovation, Brown University , Providence, Rhode Island 02912, United States.
Langmuir. 2017 Oct 31;33(43):11986-11997. doi: 10.1021/acs.langmuir.7b02764. Epub 2017 Oct 11.
Supported lipid bilayers (SLBs) have been used extensively in a variety of biotechnology applications and fundamental studies exploring lipid behavior. Despite their widespread use, various physicochemical parameters have yet to be thoroughly investigated for their impact on SLB formation. In this work, we have studied the importance of flow in inducing the rupture of surface adsorbed chicken egg-derived l-α-phosphatidylcholine (egg PC) vesicles on silica and gold surfaces via quartz crystal microbalance with dissipation monitoring (QCM-D). On silica at 25 °C, egg PC vesicles were found to adsorb in a flattened configuration (∼13 nm thick, compared to bulk vesicle diameters of ∼165 nm) but only undergo a transition to a stable SLB under flow conditions. In the absence of flow, an increase in system temperature to 37 °C was able to promote vesicle rupture and SLB formation on silica with a 10 times lower rupture time, compared to rupture under continuous flow (175 μL/min flow rate). Gold surfaces, with their increased hydrophobicity, led to less vesicle flattening once adsorbed (structures ∼60 nm thick), and did not support vesicle rupture or SLB formation, even at flow rates of up to 650 μL/min. We also showed that, under continuous flow conditions, vesicle adsorption rates on silica surfaces follow Langmuir kinetics, with an inverse dependence on bulk vesicle concentration, while an empirical power law dependence of vesicle rupture time on bulk vesicle concentration was observed. Ultimately, this work elicits fundamental insight into the importance of flow and bulk vesicle concentration in the adsorbed vesicle rupture process during SLB formation using QCM-D.
支持的脂质双层（SLB）已广泛应用于各种生物技术应用和探索脂质行为的基础研究中。尽管它们被广泛使用，但各种物理化学参数对 SLB 形成的影响尚未得到彻底研究。在这项工作中，我们通过石英晶体微天平与耗散监测（QCM-D）研究了流动在诱导吸附在硅和金表面的鸡卵衍生的 l-α-磷脂酰胆碱（卵 PC）囊泡破裂中的重要性。在 25°C 的硅上，卵 PC 囊泡被发现以扁平的构型吸附（约 13nm 厚，而与约 165nm 的囊泡直径相比），但仅在流动条件下才会转变为稳定的 SLB。在没有流动的情况下，将系统温度升高到 37°C 能够促进硅上的囊泡破裂和 SLB 形成，与连续流动下的破裂相比，破裂时间缩短了 10 倍（流速为 175μL/min）。由于金表面的疏水性增加，一旦吸附后，囊泡的扁平化程度就会降低（结构厚度约为 60nm），并且即使在高达 650μL/min 的流速下，也不会支持囊泡破裂或 SLB 形成。我们还表明，在连续流动条件下，硅表面上囊泡的吸附速率遵循 Langmuir 动力学，与体相囊泡浓度呈反比，而体相囊泡破裂时间与体相囊泡浓度呈经验幂律关系。最终，这项工作通过 QCM-D 阐明了在 SLB 形成过程中流动和体相囊泡浓度对吸附囊泡破裂过程的重要性。
