Preparation and characterization of lysozyme@carbon nanotubes/waterborne polyurethane composite and the potential application in printing inks

The composite preparation combining carbon nanotubes, biological systems and polymers to form homogenous and stable assemblies is an innovative research area with great significant for practical application of carbon nanotubes in printing, packaging and sensors areas. In this work, mull-walled carbon nanotubes (MWCNTs) was dispersed in lysozyme solution via sonification process, and then mixed with waterborne polyurethane (WPU) through a facile process. The non-covalent interaction among lysozyme, MWCNTs and WPU chains was investigated using the methods of scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy, Raman spectroscopy, fluorescence anisotropy, and X-ray diffraction. It suggests that lysozyme may adsorb nanotubes to form a certain orientation with the function of charge-pi interaction, and there may be 2 similar to 5 lysozyme biomolecules bound to hemi-CNTs side. Moreover, the homogeneous, stable and spherical nanoparticles of WPU are significantly stimulative for the stability of the MWCNTs/lysozyme/WPU composite through non-covalent interactions.