Formulation of photocleavable liposomes and the mechanism of their content release
作者:Binita Chandra、Rajesh Subramaniam、Sanku Mallik、D. K. Srivastava
DOI:10.1039/b518359f
日期:——
In pursuit of designing photocleavable liposomes as drug delivery vehicles, we synthesized several amphiphilic lipids by connecting stearyl amine (as the non-polar tail) and charged amino acids (as polar heads) via the o-nitrobenzyl derivatives. The lipids containing Glu, Asp, and Lys amino acids were subjected to photocleavage reaction by UV light, and the overall spectral changes of the chromophoric o-nitrobenzyl conjugates were determined as a function of time. The experimental data revealed that the feasibility of the cleavage reaction, nature and magnitude of the spectral changes during the course of the cleavage reaction, and their overall kinetic profiles were dictated by the type of amino acid constituting the polar head groups. The cleavage reactions of the Asp and Glu containing lipids were found to be more facile than that of the lysine-containing lipid. Using these lipids, we formulated photocleavable liposomes, and investigated the photo-triggered release of an encapsulated (within the liposomal lumen) dye as a function of time. The kinetic data revealed that the release of the liposomal content conformed to a two-step mechanism, of which the first (fast) step involved the photocleavage of lipids followed by the slow release of the liposomal content during the second step. The overall mechanistic features intrinsic to the photocleavage of Asp, Glu and Lys containing o-nitrobenzyl conjugated lipids, and their potential applications in formulating liposomes (whose contents can be “unloaded” by the UV light) as drug delivery vehicles are discussed.
为了设计可光解的脂质体作为药物传递载体,我们合成了几种两亲脂质,方法是通过o-硝基苯基衍生物将硬脂胺(作为非极性尾)和带电氨基酸(作为极性头)连接在一起。含有谷氨酸(Glu)、天冬氨酸(Asp)和赖氨酸(Lys)氨基酸的脂质在紫外光照射下进行了光解反应,色谱性o-硝基苯基结合物的总体光谱变化随着时间的推移而变化。实验数据表明,光解反应的可行性、反应过程中光谱变化的性质和幅度,以及它们的整体动力学特征都受到构成极性头部分类型的氨基酸的影响。研究发现,含有天冬氨酸和谷氨酸的脂质的光解反应比含有赖氨酸的脂质更容易进行。利用这些脂质,我们制备了可光解的脂质体,并研究了封装在脂质体腔内的染料随时间的光触发释放。动力学数据表明,脂质体内容物的释放符合两步机制,第一步(快速)涉及脂质的光解,随后在第二步中慢慢释放脂质体的内容物。本文讨论了Asp、Glu和Lys含有的o-硝基苯基结合脂质的光解的整体机制特征,以及它们在制备可通过紫外光“卸载”内容物的脂质体作为药物传递载体中的潜在应用。