Department of Chemistry, Waterloo Institute for Nanotechnology , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada.
Langmuir. 2019 Aug 27;35(34):11217-11224. doi: 10.1021/acs.langmuir.9b00677. Epub 2019 Aug 15.
Coating liposomes with a shell is a useful strategy to increase membrane stability and prevent leakage or fusion. Nucleotide/lanthanide coordination nanoparticles (NPs) are formed by a simple mixing at ambient conditions. Because some lipid headgroups contain lanthanide binding ligands, they may direct the growth of such coordination NPs. Herein, a gadolinium/adenosine monophosphate (Gd/AMP) shell was formed on liposomes (liposome@Gd/AMP) using lipids containing phosphoserine (PS) or cholinephosphate (CP) headgroups, while phosphocholine liposomes did not support the shell. Liposome binding Gd is confirmed by transmission electron microscopy (TEM). The negatively charged CP and PS liposomes reversed to positive upon Gd binding, while other metals such as Ca and Zn did not reverse the charge. Binding of Gd did not leak the PS liposomes. Then, AMP was further added to cross-link Gd on the liposome surface. A shell was formed as indicated by TEM, and the content inside the liposome remained for the PS liposomes. While adding Triton X-100 still induced leakage of the encapsulated liposomes, the shell protected the liposomes from leakage induced by ZnO NPs, suggesting a porous structure of the Gd/AMP shell which allowed penetration of Triton X-100 but not the larger ZnO NPs. This work provides a simple method to coat liposomes, and also offers a fundamental understanding of liposome adsorption of lanthanide ions.
用外壳包裹脂质体是一种增加膜稳定性、防止泄漏或融合的有效策略。在环境条件下简单混合即可形成核苷酸/镧系元素配位纳米颗粒（NPs）。由于一些脂质头部基团含有镧系元素结合配体，它们可能会指导这种配位 NPs 的生长。在此，使用含有磷酸丝氨酸（PS）或磷酸胆碱（CP）头部基团的脂质在脂质体上形成了镧（Gd）/腺苷一磷酸（AMP）壳（脂质体@Gd/AMP），而磷酸胆碱脂质体不支持壳的形成。通过透射电子显微镜（TEM）证实了脂质体结合 Gd。带负电荷的 CP 和 PS 脂质体在与 Gd 结合后反转成正电荷，而其他金属如 Ca 和 Zn 则不会反转电荷。Gd 的结合没有泄漏 PS 脂质体。然后，进一步添加 AMP 以交联脂质体表面上的 Gd。TEM 表明形成了壳，并且 PS 脂质体内部的内容物保持不变。虽然添加 Triton X-100 仍会导致封装脂质体泄漏，但外壳可保护脂质体免受 ZnO NPs 诱导的泄漏，这表明 Gd/AMP 外壳具有多孔结构，允许 Triton X-100 渗透但不允许更大的 ZnO NPs 渗透。这项工作提供了一种简单的包裹脂质体的方法，并且还提供了对脂质体吸附镧系元素离子的基本理解。
