10.1021/ja971291n
The study focuses on the synthesis and investigation of azobenzene phospholipids (APLs) in aqueous dispersions, both in pure form and when mixed with saturated and unsaturated phospholipids. The research explores the structures of the assemblies formed by these APLs, which include various forms such as large plates, and their ability to form "H" aggregates with typical aggregation numbers being multiples of three. The study utilizes techniques like microcalorimetry, dynamic light scattering, cryo-transmission electron microscopy, and reagent entrapment to analyze the assemblies. It also examines the photoreactivity of the azobenzenes, which can photoisomerize to produce cis-rich photostationary states. Interestingly, the cis-azobenzenes do not aggregate and can be reverted back to the trans form through irradiation or thermal means. The research further explores the controlled release of entrapped reagents from vesicles formed by mixed aqueous dispersions of trans-APLs with other phospholipids, demonstrating that photoisomerization can induce reagent release. The study provides insights into how aggregation influences the microstructure and macroscopic properties of the assemblies, with potential applications in drug delivery and other areas requiring photoresponsive materials.
