Gelatin-alginate coacervates for circumventing proteolysis and probing intermolecular interactions by SPR.

Complex coacervates based on natural biopolymers have been explored as a protein delivery system to provide controlled release of loaded protein and circumvent the proteolytic degradation in chronic wounds. The coacervates composed of gelatin A (GA) and sodium alginate (SA) were optimized with respect to turbidity, size, zeta potential, and polydispersity index. Bovine serum albumin (BSA), a model protein, was effectively encapsulated in the coacervates, resulting in protection from trypsin digestion and controlled release. In contrast, EGF was not encapsulated in the same coacervates. Striking difference in the encapsulation efficiencies of BSA and EGF, despite their similar net charges, was attributed to their different levels of binding to GA based on the surface plasmon resonance (SPR) biosensor analysis. In conclusion, GA and SA coacervates can protect the encapsulated protein from proteolytic degradation, demonstrating its potential as a delivery system in the chronic wounds. SPR biosensor is proposed as an analytical tool to study the interactions between polymers and proteins in association with encapsulation efficiency in complex coacervation. The results of EGF studies suggested that GA was not a suitable polymer for EGF encapsulation and therefore, further investigation would be needed to find suitable polymer systems for improved encapsulation efficiency.