Improving the binding capacity of polyelectrolyte multilayers (PEMs) is important for their application as a platform for protein capture and immobilization. In this work, we aimed to create PEMs from comb-like poly(2-hydroxyethyl methacrylate)-graft-poly(acrylic acid) (PHEMA-g-PAA) and poly(allyl amine hydrochloride) (PAH), and subsequently adsorb lysozyme throughout the film. At all deposition pH values, the thickness of (PAH/PHEMA-g-PAA)n films grow faster and more exponential than (PAH/PAA)n. In addition, (PAH/PAA)n and (PAH/PHEMA-g-PAA)n films show similar trends in thickness as a function of adsorption pH. The presence of supporting electrolyte in the deposition solutions, 0.5 NaCl, leads to thicker films by variety of pH in the absence of salt. Lysozyme binding capacities of (PAH/PHEMA-g-PAA)5 films deposited at pH values ≥5 are 2 to 5 fold higher than the values of corresponding (PAH/PAA)5 coatings, and (PAH/PHEMA-g-PAA)5 and (PAH/PAA)5 films deposited from solutions containing 0.5 M NaCl greatly enhances lysozyme adsorption, regardless of the deposition pH. The relative high lysozyme binding capacity of our new (PAH/PHEMA-g-PAA)n films provides the potential application of our PEM systems for protein purification or immobilization.
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