The phospholipid/cholesterol binary model systems are an example of simple models whose structure has caused controversy and genuine interest over many decades. The cornerstone underlying the description of such models is the answer to the question of whether these membranes are separated into coexisting phases or domains. Here, we apply label-free Raman spectroscopy and differential scanning calorimetry (DSC) to verify the phase coexistence in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/cholesterol binary model. Raman spectra demonstrate the peculiarity at 30% molar fraction of cholesterol. Above this concentration, Raman data demonstrate similar characteristics at T = 291, 298, 303 K. At lower molar fractions, at 303 K, we found the agreement of Raman spectra with the predictions of the lever rule of cholesterol. Taken together, low cooperativity of the transition at 30 mol% and the fulfillment of the lever rule suggest the existence of nanoclusters composed of approximately 4 DMPC and 2 cholesterol molecules. At 298 K, the compliance of the lever rule was found in the range from 0 to 20 mol% of cholesterol. At 291 K, the addition of 5% cholesterol leads to the abrupt change of Raman spectra parameters and their continuous evolution with the further increase of cholesterol molar fraction. It seems that cholesterol plays a twofold role in binary mixtures; it reduces the intermolecular cooperativity and forms clusters whose size and DMPC-to-cholesterol ratio depend on cholesterol concentration and temperature.

磷脂/胆固醇二元模型系统是简单模型的一个示例，其结构数十年来引起了争议和真正的兴趣。这些模型的描述所依据的基石是这些膜是否被分为共存的相或域的问题的答案。在这里，我们应用无标记拉曼光谱和差示扫描量热法（DSC）来验证1,2-二肉豆蔻酰基-sn-甘油-3-磷酸胆碱（DMPC）/胆固醇二元模型中的相共存。拉曼光谱显示胆固醇的摩尔分数为30％时的特殊性。超过此浓度，拉曼数据显示出T处的相似特征 = 291、298、303K。在较低的摩尔分数下，在303 K，我们发现拉曼光谱与胆固醇杠杆规律的预测相符。综上所述，在30 mol％时过渡的低协同性和杠杆规则的实现表明存在由大约4个DMPC和2个胆固醇分子组成的纳米簇。在298 K时，发现杠杆规则的依从性介于0至20 mol％的胆固醇之间。在291 K下，添加5％的胆固醇会导致拉曼光谱参数的突然变化，并随着胆固醇摩尔分数的进一步增加而不断变化。胆固醇似乎在二元混合物中起着双重作用。它降低了分子间的协同性，并形成了簇，簇的大小和DMPC与胆固醇的比例取决于胆固醇的浓度和温度。