ワックスベースのw1/o/w2二重エマルションの工学的安定化：高ペイロードカプセル化、浸透圧耐性、および温度活性化透過性

Water-in-oil-in-water (w₁/O/W₂) double emulsions can compartmentalize hydrophilic actives at high aqueous loadings, but osmotic gradients and interfacial transport often drive premature leakage. This remains a key limitation for high-payload hydrophilic formulations exposed to dilution or osmotic shocks during handling, reconstitution, or administration. Here, we engineer wax-shelled, gel-cored w₁/O/W₂ double emulsions designed under iso-osmotic conditions to combine storage-stable retention at 25°C (fully solid wax state) with temperature-activated permeability at a high internal water fraction (70%). Double emulsions were prepared with a polyacrylate-gelled inner aqueous phase and either liquid oil or semi-crystalline wax as the middle phase, and characterized by confocal microscopy, release assays (NaCl conductimetry and metformin dialysis/UV at 37°C, with additional 25°C datasets for wax systems), Weibull kinetic modelling (and early-time power-law analysis at 25°C), and oscillatory rheology. Iso-osmotic formulation enabled high initial encapsulation and preserved internal compartmentalization. Release profiles revealed two regimes: minimal leakage at low temperature and a marked increase in permeability upon heating, consistent with barrier-controlled transport. Compared with liquid oil, wax systems provided stronger retention but exhibited partial trapping after triggering. Finally, a CaCl₂/alginate external gelation model coupled to rheology quantified the triggered sol/gel transition and the mechanical response of wax-based double-emulsion assemblies under thermal stimulation and compressive loading.