Abstract

We describe the dynamics of lipoic acid (LA) alone, incorporated in liposomes and as a part of nanoemulsions. Mass spectrometry shows that LA in water forms aggregates of two or three molecules in the form of a negatively charged ion and a neutral molecule. Phosphatidylcholine (PC)-based nanoforms of LA as liposomes and nanoemulsions with a particle size equal to 145 nm are characterized by a high degree of incorporation of LA into the nanoparticles and long-term stability during storage at room temperature. Dynamic light scattering (DLS) gives the polydispersity index of the nanoforms (> 0.3), characterizing the homogeneity of the obtained nanodispersions. We found that such emulsions can significantly (5 ×) increase the concentration of LA in the aqueous phase (5–7 mg/mL) when compared with an aqueous solution of LA (1 mg/mL) and by 40% when compared with PC liposomes (4 mg/mL). Moreover, the inclusion of LA in liposomes and nanoemulsions from PC did not change the neutral ζ-potential characteristic of PC nanoforms. CryoTEM established that the structural organization of the liposomes practically did not differ from nanoemulsions and both nanoforms contained both multilayer and single-layer vesicles. When studying the release kinetics of LA from phosphatidylcholine nanoforms, we found that at 22 h, 45–55% of LA was released from nanoparticles, but that at the initial stage of the process LA was slowly released from the nanoemulsions and rapidly from the liposomes. Conductance measurements indicate that LA delivered in all the three forms increase membrane permeability, though this result is most marked with the LA in PC liposomes.

中文翻译：

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基于磷脂酰胆碱的硫辛酸纳米形式：生产和特性

摘要

我们描述了单独的硫辛酸 (LA) 的动力学，纳入脂质体并作为纳米乳液的一部分。质谱表明，水中的 LA 以带负电荷的离子和中性分子的形式形成两个或三个分子的聚集体。基于磷脂酰胆碱 (PC) 的 LA 纳米形式作为脂质体和粒径等于 145 nm 的纳米乳剂，其特征在于 LA 高度掺入纳米粒子中，并且在室温下储存期间具有长期稳定性。动态光散射 (DLS) 给出纳米形式的多分散指数 (> 0.3)，表征所得纳米分散体的均匀性。我们发现，与 LA 水溶液 (1 mg/mL) 相比，此类乳液可显着 (5 ×) 增加水相中 LA 的浓度 (5–7 mg/mL)，与 PC 相比，可增加 40%脂质体 (4 毫克/毫升)。此外，在来自 PC 的脂质体和纳米乳剂中加入 LA 并没有改变中性ζ -PC 纳米形式的电位特性。CryoTEM 确定脂质体的结构组织实际上与纳米乳液没有区别，两种纳米形式都包含多层和单层囊泡。在研究 LA 从磷脂酰胆碱纳米形式的释放动力学时，我们发现在 22 小时时，45-55% 的 LA 从纳米颗粒中释放出来，但在该过程的初始阶段，LA 从纳米乳剂中缓慢释放，并从脂质体中快速释放. 电导测量表明，以所有三种形式递送的 LA 增加了膜渗透性，尽管这一结果最明显的是 PC 脂质体中的 LA。