Charge-tunable photoresponsive catanionic vesicles enabling electrostatic probe loading and dual light/pH-modulated release

Stimuli-responsive surfactant self-assembly offers versatile opportunities to tailor colloidal structure and function through simple formulation strategies. Here, we report a photoresponsive catanionic vesicle system composed of the double-chained cationic surfactant didodecyldimethylammonium bromide (DDAB) and an anionic amphiphilic 2-hydroxychalcone derivative bearing a sulfonate headgroup (C 8 SCh). The self-assembly and phase behavior of the individual components and their mixtures are characterized, revealing a broad vesicle-forming compositional range. Notably, three molar fractions ( x Ch = 0.10, 0.20, and 0.80) yield dispersions composed exclusively of vesicles, enabling the formation of either positively or negatively charged vesicles using the same pair of molecular building blocks. Strong synergistic interactions between DDAB and C 8 SCh are evidenced by markedly reduced critical aggregation concentrations and negative interaction parameters. The incorporation of the chalcone photoswitch endows the vesicles with light responsiveness, inducing composition-dependent morphological rearrangements in both DDAB-rich and C 8 SCh-rich regimes. Under mildly acidic conditions (pH = 4.5), partial conversion of the chalcone to its flavylium form introduces an additional, independent stimulus that further modulates the structure of C 8 SCh-rich vesicles. This intrinsic charge tunability enables highly efficient, charge-selective electrostatic entrapment of both anionic and cationic molecular probes—carboxyfluorescein (CF) and doxorubicin (DOX), respectively—without the need for active loading strategies. Importantly, cargo release is selectively modulated by vesicle composition and external stimuli: light stimulation enhances the release of CF from DDAB-rich vesicles, while the combined action of acidification and irradiation significantly increases DOX release from C 8 SCh-rich vesicles. Overall, these results establish a simple catanionic system in which surface charge, morphology, and release behavior are jointly controlled by composition, light, and pH, offering a formulation-simple, versatile platform with potential applications in controlled delivery.