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Abstract：
OBJECTIVE: The surface dilatational and shear moduli of surfactant and protein interfacial layers can be derived from surface pressures measured with a Wilhelmy plate parallel, ΔΠpar and perpendicular ΔΠperp to the barriers in a Langmuir trough.
METHODS: Applying area oscillations, A0+ ΔAeiωt, in a rectangular Langmuir trough induces changes in surface pressure, ΔΠpar and ΔΠperp for monolayers of soluble palmitoyl-lysophosphatidylcholine (LysoPC), insoluble dipalmitoylphosphatidylcholine (DPPC), and the protein β-lactoglobulin to evaluate Es∗+Gs∗=A0ΔΠparΔA and Es∗-Gs∗=A0ΔΠperpΔA. Gs∗ was independently measured with a double-wall ring apparatus (DWR) and Es∗ by area oscillations of hemispherical bubbles in a capillary pressure microtensiometer (CPM) and the results were compared to the trough measurements.
RESULTS: For LysoPC and DPPC, A0ΔΠparΔA≅A0ΔΠperpΔA meaning Es∗≫Gs∗ and Es∗≅A0ΔΠparΔA≅A0ΔΠperpΔA. Trough values for Es∗ were quantitatively similar to CPM when corrected for interfacial curvature. DWR showed G∗ was 4 orders of magnitude smaller than Es∗ for both LysoPC and DPPC. For β-lactoglobulin films, A0ΔΠparΔA>A0ΔΠperpΔA and Es∗ and Gs∗ were in qualitative agreement with independent CPM and DWR measurements. For β-lactoglobulin, both Es∗ and Gs∗ varied with film age and history on the trough, suggesting the evolution of the protein structure.
METHODS: Applying area oscillations, A0+ ΔAeiωt, in a rectangular Langmuir trough induces changes in surface pressure, ΔΠpar and ΔΠperp for monolayers of soluble palmitoyl-lysophosphatidylcholine (LysoPC), insoluble dipalmitoylphosphatidylcholine (DPPC), and the protein β-lactoglobulin to evaluate Es∗+Gs∗=A0ΔΠparΔA and Es∗-Gs∗=A0ΔΠperpΔA. Gs∗ was independently measured with a double-wall ring apparatus (DWR) and Es∗ by area oscillations of hemispherical bubbles in a capillary pressure microtensiometer (CPM) and the results were compared to the trough measurements.
RESULTS: For LysoPC and DPPC, A0ΔΠparΔA≅A0ΔΠperpΔA meaning Es∗≫Gs∗ and Es∗≅A0ΔΠparΔA≅A0ΔΠperpΔA. Trough values for Es∗ were quantitatively similar to CPM when corrected for interfacial curvature. DWR showed G∗ was 4 orders of magnitude smaller than Es∗ for both LysoPC and DPPC. For β-lactoglobulin films, A0ΔΠparΔA>A0ΔΠperpΔA and Es∗ and Gs∗ were in qualitative agreement with independent CPM and DWR measurements. For β-lactoglobulin, both Es∗ and Gs∗ varied with film age and history on the trough, suggesting the evolution of the protein structure.
摘要：
目的：表面活性剂和蛋白质界面层的表面膨胀和剪切模量可以从使用Wilhelmy平板平行测量的表面压力得出，ΔΠpar和垂直ΔΠperp到Langmuir槽中的屏障。
方法：应用面积振荡，A0+ΔAeiωt，在矩形朗缪尔槽中引起表面压力的变化，可溶性棕榈酰溶血磷脂酰胆碱（LysoPC）单层的ΔΠpar和ΔΠperp，不溶性二棕榈酰磷脂酰胆碱（DPPC），和蛋白质β-乳球蛋白来评估Es*Gs*=A0ΔΠparΔA和Es*-Gs*=A0ΔΠperpΔA。在毛细管压力微张力计（CPM）中，用双壁环形设备（DWR）和Es*通过半球形气泡的面积振荡独立测量Gs*，并将结果与槽测量结果进行比较。
结果：对于LysoPC和DPPC，A0ΔΠparΔA^A0ΔΠperpΔA的意思是Es*Gs*和Es*A0ΔΠparΔA^A0ΔΠperpΔA。当校正界面曲率时，Es*的槽值在数量上与CPM相似。DWR显示，LysoPC和DPPC的G*比Es*小4个数量级。对于β-乳球蛋白膜，A0ΔΠparΔA>A0ΔΠperpΔA和Es*和Gs*与独立的CPM和DWR测量在质量上是一致的。对于β-乳球蛋白，Es*和Gs*都随着电影年龄和历史的低谷而变化，表明蛋白质结构的进化。
方法：应用面积振荡，
结果：对于LysoPC和DPPC，
