Acylated peptides, which are commonly treated as micelles due to their structure, are susceptible to a unique physical instability, spontaneous emulsification, in the presence of certain types of hydrophobic surfaces. In this work, experimental techniques include light scattering, microscopy, and circular dichroism are used to characterize the physical properties of the Semaglutide emulsions as a function of conditions. The equilibrium properties of this so-called Ouzo effect for acylated peptide were predicted by a charge-stabilized droplet model, implying the controlling parameters of the microemulsion droplets. In non-equilibrium emulsification kinetics, the Ouzo process is found to be dependent on the hydrophobic surface. However, in all different conditions, the kinetics falls onto a master curve formed from a two-stage reaction kinetics model, revealing the nature of the whole process. Furthermore, the distinctions observed from different surfaces are explained by the surface wettability combining with the adsorption/desorption process. This work provides insights into this unique colloidal physics phenomenon and guides the formulation and storage of the acylated peptides in pharmaceutical industries.

Spontaneous emulsification of model acylated peptide: An investigation on semaglutide

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