Heterofunctional Interfaces Achieve Dual Protein Adsorption on Polyelectrolyte Multilayers

Abstract

Two types of polyelectrolyte multilayers were formed on both sides of a substrate by integrating an alternate adsorption process with an alternate drop-coating process. We used poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) as strong polyelectrolytes. Each side of the substrate was covered with each polyelectrolyte, PDDA and PSS, then heterofunctional interfaces were obtained. Fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) and cytochrome c (cyt c) were used as model proteins for evaluating dual protein adsorption. The proteins FITC-BSA and cyt c exhibited anionic and cationic charges, respectively, in tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer solution (pH 7.4). From the results of protein adsorption from individual protein solutions, the FITC-BSA and cyt c proteins were adsorbed on the outermost surfaces of PDDA and PSS, respectively. Moreover, dual protein adsorption was achieved in the case of a protein mixture. This result indicated that polyelectrolyte multilayers could easily control the surface charge to regulate protein adsorption from the protein mixture. In summary, a heterofunctional interface prepared from polyelectrolyte multilayers achieved dual protein adsorption on each side of a substrate from a protein mixture.