Sphingomyelin (SM) molecules are major lipid components of plasma membranes that are involved in functional domains. Among natural SMs, that found in milk (milk-SM) exhibits important acyl chain heterogeneities in terms of length and saturation, which could affect the biophysical properties and biological functions of the milk fat globule membrane or of liposome carriers. In this study, the thermotropic and mechanical properties of milk-SM, synthetic C16:0-SM, C24:0-SM and the binary mixtures C16:0-SM/C24:0-SM (50:50% mol) and C24:0-SM/C24:1-SM (95:5% mol) bilayer membranes were investigated using differential scanning calorimetry and atomic force microscopy, respectively. Results showed that acyl chain length, heterogeneity and unsaturation affected i) the temperature of phase transition of SM bilayers, and ii) the mechanical properties of liposome (diameter < 200 nm) membranes in the gel phase, e.g. the Young modulus E and the bending rigidity k_C. This study increases our knowledge about the key role of naturally complex lipid compositions in tailoring the physical properties of biological membranes. It could be also used in liposomes development e.g. to select the suitable lipid composition according to usage.

鞘磷脂（SM）分子是质膜中涉及功能域的主要脂质成分。在牛奶中发现的天然SM（牛奶SM）在长度和饱和度方面显示出重要的酰基链异质性，这可能会影响牛奶脂肪小球膜或脂质体载体的生物物理特性和生物学功能。在这项研究中，牛奶-SM，合成的C16：0-SM，C24：0-SM以及二元混合物C16：0-SM / C24：0-SM（50：50％mol）和C24的热致和力学性能分别使用差示扫描量热法和原子力显微镜研究了：0-SM / C24：1-SM（95：5％mol）双层膜。结果表明，酰基链长度，异质性和不饱和度会影响i）SM双层的相变温度，ķ _Ç。这项研究增加了我们对天然复杂脂质组合物在调节生物膜物理特性中的关键作用的认识。它也可用于脂质体开发，例如根据用途选择合适的脂质组合物。