Peptides and peptidomimetics that self-assemble through LLPS have recently emerged as vital building blocks for creating functional biomaterials due to their unique physicochemical properties and dynamic nature. One of life’s most distinctive signatures is its selectivity for chiral molecules and, to date, coacervates comprised of D-amino acids have not been reported. Here, we demonstrate that histidine-rich repeats of (GHGXY)4 (X=L/V/P) and their enantiomers undergo LLPS, opening new avenues for enhancing coacervate stability. Through a series of biophysical studies, we find that the droplet size was simply tunable based on L, V, or P substitution and molecular cargo ranging from 600-150,000 Da is efficiently recruited in a bioactivity-preserving aqueous environment during phase separation. Mechanistic studies reveal that the droplets enter cells via energy-dependent endocytic pathways, exhibit composition-selective fusion properties, and effectively deliver molecular therapeutics in a variety of cell types. Finally, we show that the coacervates enhance antigen presentation to CD4+ and CD8+ T cells resulting in robust proliferation and production of functional cytokines. Collectively, our study outlines the development and characterization of enantiomeric peptide coacervates as attractive vaccine delivery vehicles with tunable physicochemical properties.
