Bhamla M Saad, Nash Walter L, Elliott Stacey, Fuller Gerald G
†Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.
‡Alcon Research Ltd., Fort Worth, Texas 76134, United States.
Langmuir. 2015 Apr 7;31(13):3820-8. doi: 10.1021/la503437a. Epub 2014 Oct 14.
Insoluble lipids serve vital functions in our bodies and interact with biomedical devices, e.g., the tear film on a contact lens. Over a period of time, these naturally occurring lipids form interfacial coatings that modify the wettability characteristics of these foreign synthetic surfaces. In this study, we examine the deposition and consequences of tear film lipids on silicone hydrogel (SiHy) contact lenses. We use bovine meibum, which is a complex mixture of waxy esters, cholesterol esters, and lipids that is secreted from the meibomian glands located on the upper and lower eyelids of mammals. For comparison, we study two commercially available model materials: dipalmitoylphosphatidylcholine (DPPC) and cholesterol. Upon deposition, we find that DPPC and meibum remain closer to the SiHy surface than cholesterol, which diffuses further into the porous SiHy matrix. In addition, we also monitor the fate of unstable thin liquid films that consequently rupture and dewet on these lipid-decorated surfaces. This dewetting provides valuable qualitative and quantitative information about the wetting characteristics of these SiHy substrates. We observe that decorating the SiHy surface with simple model lipids such as DPPC and cholesterol increases the hydrophilicity, which consequently inhibits dewetting, whereas meibum behaves conversely.
不溶性脂质在我们体内发挥着重要作用，并与生物医学设备相互作用，例如隐形眼镜上的泪膜。随着时间的推移，这些天然存在的脂质会形成界面涂层，从而改变这些外来合成表面的润湿性特征。在本研究中，我们研究了泪膜脂质在硅水凝胶（SiHy）隐形眼镜上的沉积及其后果。我们使用牛睑脂，它是一种蜡酯、胆固醇酯和脂质的复杂混合物，由位于哺乳动物上下眼睑的睑板腺分泌。作为比较，我们研究了两种市售的模型材料：二棕榈酰磷脂酰胆碱（DPPC）和胆固醇。沉积后，我们发现DPPC和睑脂比胆固醇更靠近SiHy表面，胆固醇会进一步扩散到多孔的SiHy基质中。此外，我们还监测了不稳定的薄液膜在这些脂质修饰表面上破裂和去湿的过程。这种去湿提供了有关这些SiHy基底润湿性的有价值的定性和定量信息。我们观察到，用DPPC和胆固醇等简单模型脂质修饰SiHy表面会增加亲水性，从而抑制去湿，而睑脂的作用则相反。
