Characterization of amphoteric multilayered thin films by means of zeta potential measurements

Multilayer films of amphoteric methylated collagen were assembled on SOURCE 15S or SOURCE 15Q beads by sequential electrostatic deposition with negatively charged methylacrylic acid-hydroxyethyl methacrylate-methyl methacrylate (MAA-HEMA-MMA) terpolymer. Methylated collagen and terpolymer were deposited under conditions where they were oppositely charged to one another, thereby facilitating growth of the films through electrostatic interactions. Measurements revealed alternating positive and negative ζ-potential with the deposition of each methylated collagen and terpolymer layer, respectively. Assembly pH had a remarkable influence on ζ-potential of the assembled multilayers and the deposition of methylated collagen will be frustrated when the assembly pH is up to 9.0. In addition, ionic strength (NaCl concentration) showed an intricate effect on ζ-potential of the films of amphoteric methylated collagen.