Construction of photoresponsive azobenzene-decorated cationic surfactant-based self-assembled vesicles and controlled drug release

Abstract Surfactant aggregates possess a unique feature of space partitioning, and hence are widely used as drug carriers. A comprehensive understanding of the regulation of surfactant aggregation behavior can achieve the controlled release of drugs. In this work, the surface activity and photoisomerization behavior of the synthetically prepared azobenzene-functionalized cationic surfactant (AzoNC8) were thoroughly studied by analyzing the surface tension and UV-Vis absorption data, respectively. Furthermore, the self-assembling tendency of AzoNC8 with β-cyclodextrin (β-CD) was also monitored by proton nucleic magnetic resonance (1H NMR) and scanning electron microscopy (SEM). The AzoNC8 initially formed a 1:1 inclusion complex with β-CD and subsequently 2AzoNC8 @ 2β-CD self assembly unit was formed. At 10 mM concentration, the AzoNC8/β-CD self-assembled system was found to develop a vesicular structure. The photo-responsive property of AzoNC8/β-CD was further investigated using UV-Vis, 1H NMR, and transmission electron microscopy (TEM). The self-assembled system was found to exhibit a fast photo-responsive behavior under UV light and a reversible photo-response under visible light. Interestingly, the photo-induced cis-trans isomerization altered the driving force associated with the self-assembly of AzoNC8/β-CD, thereby modulating the self-assembled morphologies. In addition, an investigation with the antitumor drug of doxorubicin hydrochloride (DOX) at different pH values revealed that the self-assembly-based vesicles exhibited a quick photo-responsive drug release and a weak acid environment could improve the rate and amount of the release. Therefore, the AzoNC8/β-CD self-assembled system might be used for the controlled release of drugs and could be a promising drug carrier.