Design of Stimuli-Responsive Minimalist Heptad Surfactants for Stable Emulsions

Peptide surfactants have been extensively investigated with various applications in detergents, foods, and pharmaceutics due to their biodegradability, biocompatibility, and customizable structures. Traditional peptide surfactants are often designed in a "head-to-tail" fashion mimicking chemical surfactants. Alternatively, a side-by-side design pattern based on heptad repeats offers a new approach to designing new peptide surfactants. However, minimalist peptide design using a single heptad for stabilizing interfaces remains largely unexplored. We designed four heptad surfactants responsive to metal ions and compared their emulsification performance with a three-heptad peptide AM1. Among them, the HK peptide generated emulsions exhibiting good stability over months. Factors such as buffering salts, ionic strength, and emulsion dilutions were further optimized to uncover their impacts on emulsion properties. Our findings deepen the understanding of emulsion properties and provide practical insights for characterizing peptide-based emulsions, paving the way for their broader utilization in diverse applications.