Complex coacervation of silk fibroin and hyaluronic acid

This study aimed to investigate the pH-induced complexation of silk fibroin (SF) and hyaluronic acid (HA). SF–HA complex coacervation was investigated by monitoring turbidity of the SF–HA system under slow acidification. Gravimetric analysis was performed to determine the yield of complex coacervation and viscosity of the system was measured to study the formation of the complexes at different pH values. The influences of total biopolymer concentration and biopolymer weight ratio on complex coacervation were examined during the analyses. Formation of the complexes was evidenced by the minimum viscosity and the maximum turbidity observed in the system. SF–HA complexes were formed within the pH–window of 2.5–3.5 regardless of the total biopolymer concentration or biopolymer ratio. Complex coacervation of SF–HA showed a reversible behavior and coacervation could be handled even in excess amounts of the biopolymers, which pointed out a non-stoichiometric complexation.