Catalytic Assembly of Peptides Mediated by Complex Coacervates

The assembly of peptides is generally mediated by liquid-liquid phase separation, which enables control over assembly kinetics, final structure, and functions of peptide-based supramolecular materials. Modulating phase separation can alter the assembly kinetics of peptides by changing solvents or introducing external fields. Herein, we demonstrate that the assembly of peptides can be effectively catalyzed by complex coacervates. The negatively charged sodium alginate (SA) can form complex coacervates with the positively charged KLVFFAE (Aβ_16-22, abbreviated as KE) peptide, thereby lowering the nucleation barrier and promoting the assembly of the peptide. As the binding affinity of SA-KE and the dosage of SA decrease, the system shifts from a relatively inefficient template-induced assembly to a highly efficient catalytic assembly before ultimately reverting to slow spontaneous assembly. Therefore, both the affinity as well as the stoichiometry do not follow the intuitive rule that "more is better", but rather there exists an optimal value that maximizes the rate of assembly.