我們使用原子力顯微鏡研究室溫下DPPC，POPC，及POPC/DPPC膜的形貌。這些膜是以雲母片為支撐基板的脂質雙層 (supported lipid bilayers)。我們比較以旋轉塗佈方法 (spin coating) 及脂球融合方法 (vesicle fusion) 製作的脂質雙層。這兩種方法製造的脂質雙層有相似的厚度，但旋轉塗佈方法可得到較一致的脂質覆蓋率。POPC (一種低熔點的脂質，Tm = -7 oC) 膜因其液態特性而呈現較DPPC (一種高熔點的脂質，Tm = 40 oC) 膜均勻的形貌，以及較小的脂質雙層厚度。我們也得到POPC/DPPC混和脂膜的形貌與DPPC濃度的關係圖，其中我們觀察到脂質不互溶性 (lipid immiscibility)。對脂質雙層厚度分析的結果暗示“富含POPC區塊”（POPC-rich domains）與“富含DPPC區塊”（DPPC-rich domains）共存。加入愈多DPPC會增加較厚之脂質雙層（即富含DPPC區塊）的比例，因此造成POPC/DPPC混和脂膜有較大的脂質雙層平均厚度。 We have studied the morphologies of DPPC, POPC, and POPC/DPPC membranes at room temperature using atomic force microscopy (AFM). The membranes were lipid bilayers supported on mica surfaces. Lipid bilayers prepared by spin coating and vesicle fusion were compared. Both methods produce bilayers of similar thickness. However, spin coating results in more uniform lipid coverage. Because of the fluid nature of the bilayers, POPC (a low-melting lipid with Tm of -7 oC) present a more homogeneous morphology and a smaller bilayer thickness than DPPC (a high-melting lipid with Tm of 40 oC). The morphologies of binary mixtures of POPC and DPPC were obtained as a function of DPPC concentration. Lipid immiscibility is observed. Analysis of bilayer thickness suggests coexistence of POPC-rich and DPPC-rich domains. Addition of DPPC increases the fraction of the thicker-bilayer (i.e. DPPC-rich) domains, thus increase the average bilayer thickness of POPC/DPPC bilayers.
