Abstract:

The stability of w/o/w emulsions has been significantly improved by using a blend of nonionic surfactant (Span 80) and bovine serum albumin (BSA) as an interfacial complex in the inner phase. Improved stability was obtained by replacing the common nonionic hydrophilic monomeric emulsifier by BSA in the outer phase. Optimum stability and droplet size of double emulsion was achieved with 0.2 wt% BSA + 10 wt% Span 80 as emulsifier I and 5.0 wt% Span 80-Tween 80 (2:3) or 0.1 wt% BSA as emulsifier II. Significant slow release of NaCl was obtained. The results were examd. in view of Higuchi mechanism and it was found that one can account for the thickness of the inner interfacial complex from the plot of B (diffusion parameter correlated to the fraction of electrolyte release) vs. time. It can be clearly seen that in the inner phase the surfactant and the BSA act synergistically (active interfacial complex), and enhance stability and reduce release. In the outer phase BSA has mainly a stabilizing effect with a limited release retardation effect. Effective diffusion coeffs. for each BSA concn. in the inner and outer phase have been calcd. and evaluated in a view of the diffusion controlled mechanism and the thickness of the viscoelastic film which is formed. [on SciFinder(R)]