Effect of Loading Strategy on Methylene Blue Encapsulation in Ethosomes: A Comparative Study of Aqueous and Ethanol Phases

≈ 96 nm), but is accompanied by a lower encapsulation efficiency (EE ≈ 36% versus 48%). The results indicate that a reduction in vesicle size does not necessarily lead to higher encapsulation of hydrophilic cationic MB and may be associated with a decrease in the total internal aqueous volume as well as an increased contribution of a weakly bound surface-associated dye fraction. Spectral analysis indicates the preservation of a predominantly monomeric form of MB within ethosomes, while differences in ζ-potential suggest distinct localization of the dye within the vesicular systems. Overall, the results highlight the importance of optimizing the loading protocol in the development of ethosomal drug delivery systems for photodynamic therapy and topical applications.