Design of supports based on S-layer proteins-poly(acrylic) particles with varying surface properties

This work proposes the study of the preparation of S-layer proteins-polymer particles supports by adsorption of the proteins on the polymer particles in aqueous dispersion. S-layer proteins were isolated from two Lentilactobacillus kefiri strains exhibiting different aggregative properties. Polyacrylic particles with similar sizes (around 70 nm) but different surface functionality (alkyl, hydroxylic, carboxylic), were obtained by emulsion polymerization and characterized. Combining them, adsorption isotherms were built. Adsorption isotherms follow the Langmuir-Freundlich model and show that the maximum amount of adsorbed protein was dependent on the protein/polymer combination. Both proteins showed a preference for particles containing carboxylic groups at the surface. Although the protein isolated from the non-aggregating strain presented the highest affinity for this surface, the protein obtained from the aggregating one led to the maximum amount of sorbed protein. The studies performed before and after sorption showed that the S-layer protein isolated from the aggregating strain presented a higher capacity to modify its secondary structure.