In-situ ATR-FTIR and AFM studies on poly(etyhleneimine )/poly(acrylic acid) multilayers: Dependence on medium parameters and protein selectivity

摘要

Biomedical applications of polyelectrolyte multilayers (PEM), initiated by Decher, are increasing in the last years justifying fundamental model studies on their interaction to biofluids. Since generally PEM films have been proven so far to be highly specific for different proteins due to their isoelectric point (IEP), we were further interested if PEM are also selective to proteins from a multicomponent mixture, which is a more realistic model for biofluids and is often encountered in biosensor and separation technology. To elucidate this, we performed model studies on electrostatically mediated protein sorption from a binary mixture consisting of lysozyme (LYZ) and concanavalin A (COA) at PEM of consecutively adsorbed poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAC), which was published recently therein. The PEM/protein interaction was varied by pH and the outermost polyelectrolyte layer type. in-situ ATR-FTIR spectroscopy was chosen as basis technique supported by AFM to characterize quantitatively PEM deposition and protein sorption.