Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5370392 | Applied Surface Science | 2006 | 7 Pages |
Abstract
Mixed monolayers of dipalmitoylposphatidylcholine (DPPC) and bilirubin (BR) were prepared on different subphases. The properties of DPPC/BR monolayer, such as collapse pressure (Ïcoll), limiting area per molecule (Alim), surface compressibility modulus, free energy (ÎGmix) and excess free energy (ÎGex), were investigated based on the analysis of the surface pressure-area isotherms on pure water. The results showed that DPPC and BR were miscible and formed non-ideal mixed monolayers at the air/water interface. With the molar fraction of BR (XBR) increasing, the LE-LC coexistence region of DPPC monolayer was eliminated gradually. The DPPC/BR complex (MD-B) of 1:2 stoichiometry formed as a result of the strong hydrogen bonds between the polar groups of DPPC and BR. The studies of effects of pH values and calcium ions in subphase on the DPPC/BR monolayers showed that the mixed monolayer became expanded on alkali aqueous solution and on 1Â mmol/L CaCl2 aqueous solution. The orientation of DPPC and BR at air/water interface was also discussed.
Related Topics
Physical Sciences and Engineering
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Authors
Yuhua Shen, Yufeng Tang, Anjian Xie, Jinmiao Zhu, Shikuo Li, Yong Zhang,