Sardone Laura, Pignataro Bruno, Castelli Francesco, Sarpietro Maria G, Nicolosi Giovanni, Marletta Giovanni
Laboratory for Molecular Surfaces and Interfaces (LAMSUN), Dipartimento di Scienze Chimiche, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
J Colloid Interface Sci. 2004 Mar 15;271(2):329-35. doi: 10.1016/j.jcis.2003.11.037.
The molecular interaction of quercetin-3-O-palmitate (QP) with dimyristoylphosphatidylcholine (DMPC) has been studied. Film balance measurements of the average molecular area vs QP molar fraction in DMPC/QP mixed monolayers showed that relevant positive deviations from ideality, i.e., a less dense monolayer packing, occurred for a temperature of 10 degrees C, below the critical melting transition temperature of DMPC monolayers T c m approximately equal 20 degrees C), while ideal behavior was observed at 37 degrees C, above this phase transition temperature. The positive deviation observed at low temperatures in the average molecular area increased with the surface pressure. Scanning probe microscopy measurements performed on mixed monolayers transferred on mica showed that the deviations from ideality were connected to the formation of nanometric-scale QP-rich domains. However, the formation of aggregates was observed only for relatively high-QP molar fractions X QP > or = 0.25 at 10 degrees C, while it was not observed at 37 degrees C, i.e., when the ideal mixing was found at the air/water interface. The observed effects are explained in terms of a temperature- and surface pressure-dependent phase-separation process based on the predominance at low temperature and low molecular mobility of QP-QP and DMPC-DMPC aggregation forces, prompting the formation of QP-rich domains embedded in a DMPC-rich matrix. High temperature prompts the QP/DMPC ideal mixing.
已对槲皮素 - 3 - O - 棕榈酸酯（QP）与二肉豆蔻酰磷脂酰胆碱（DMPC）的分子相互作用进行了研究。对DMPC/QP混合单分子层中平均分子面积与QP摩尔分数的膜天平测量表明，在10℃（低于DMPC单分子层的临界熔化转变温度Tcm约20℃）时，出现了与理想情况相关的正偏差，即单分子层堆积密度较低，而在37℃（高于该相变温度）时观察到理想行为。在低温下平均分子面积中观察到的正偏差随表面压力增加。对转移到云母上的混合单分子层进行的扫描探针显微镜测量表明，与理想情况的偏差与纳米级富含QP的区域的形成有关。然而，仅在10℃时，对于相对较高的QP摩尔分数XQP≥0.25观察到聚集体的形成，而在37℃时未观察到，即在空气/水界面发现理想混合时。根据基于低温下QP - QP和DMPC - DMPC聚集力占主导以及低分子迁移率的温度和表面压力依赖性相分离过程来解释观察到的效应，这促使在富含DMPC的基质中形成富含QP的区域。高温促使QP/DMPC理想混合。
