Thermoresponsive multilayer films based on ionic elastin-like recombinamers

Abstract

Thermoresponsive multilayer films consisting of ionic elastin-like recombinamers (ELRs) were prepared using a layer-by-layer technique on model substrates. The ELR polymer containing lysine units served as a polycation and the one with glutamic acid served as a polyanion. The build up process was followed by UV/Vis absorption spectroscopy and atomic force microscopy (AFM). The film formation was optimized by measuring the adsorption at various pH values. The application of monodisperse recombinamers of similar main chain with precisely controlled, evenly distributed and equidistanced charged moieties lead to the formation of stable films at biologically relevant pH values (very efficiently at pH = 7), in spite of the limited number of charged groups in these polypeptides. The fabricated films were found to be temperature-responsive around the physiological temperature, as shown using AFM, spectroscopic ellipsometry and contact angle measurements. This phenomenon increases the resistance of such polypeptide films to salty solutions, which is important for their potential applications as biocompatible nanocoatings.