Lysozyme uptake into pharmaceutical grade fucoidan/chitosan polyelectrolyte multilayers under physiological conditions

Polyelectrolyte multilayers composed of pharmaceutical grade fucoidan and chitosan have been assembled and studied in terms of their response to physiological solution conditions and the presence of lysozyme. The influence of phosphate buffered saline (PBS) solution on the multilayer was interrogated using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). The combination of the techniques reveal that the polyelectrolyte multilayers swell when exposed to PBS after build-up and may include a small degree of mass loss as the film swells. The degree of swelling was influenced by the terminating layer of the multilayer. Upon exposure to lysozyme, it was observed that some deswelling occurred, as the enzyme adsorbed onto and permeated into the multilayer. The behaviour of the multilayer as a potential reservoir for lysozyme contrasts with the interaction with bovine serum albumin, which did not penetrate into the multilayer, indicating either exclusion by size or due to the overall net negative charge of the film. (C) 2020 Elsevier Inc. All rights reserved.