Synthesis Of Lysozyme/Carbon Nanotube Hybrid Material And The Non-covalent Interaction Mechanism

Integrating carbon nanotubes with proteins to form novel hybrid functional assemblies hold great potential application in medical,nanotechnology and materials science areas.The hybrid system is currently faced with the problem that it is difficult to experimentally verify the interaction mechanism between CNTs and proteins,including the difficulty of controlling the composition of CNTs and the spatial structure of proteins.In this paper,we investigated and compared the different functionalized multi-walled carbon nanotubes(MWCNTs)regarding their interaction with protein and their ability to alter protein structure.Lysozyme(LYZ)was used as the model protein.In addition,we proposed an innovative design that by inducing lysozyme to assembly into phase-transited nanofilm to adsorb the prepared carbon nanotubes and analyzing the interaction mechanism of lysozyme/carbon nanotubes hybrids.It is expected to change the spatial structure of protein and assemble the core region of amino acid sequence,and analyzed the non-covalent interaction mechanism of CNTs and lysozyme on a microscopic scale.The prepared CNTs/LYZ hybrid materials were characterized by Scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,Raman spectroscopy,Circular dichroism spectroscopy,UV-vis absorption spectroscopy,Fluorescence spectroscopy,X-ray photoelectron spectroscopy,?-? measurements,with lysozyme phase transition as a supplementary evidence.It was found that when CNTs and LYZ are combined into CNTs/LYZ hybrid material,the secondary structure of lysozyme is not completely destroyed,only slightly affected,and the order of the secondary structure is preserved.There is hydrogen bonding in the interaction mechanism between them,and different groups grafted on CNTs will affect the size and site of hydrogen bonding.Due to the grafted polar group and high degree of functionalization,the hydrogen bonding between CNTs-ac and LYZ is stronger.The degree of functionalization of CNTs-Cl is relatively low and the grafted group is less polar,thence the hydrogen bond with LYZ is relatively small.CNTs may be more bound near Trp 62 and Trp 108,which are mainly responsible for the fluorescence emission of lysozyme.The spatial structure of CNTs/LYZ hybrid material protein higher rigidity,which improves the stability and dispersibility of the protein.Moreover,lysozyme has not negatively affected the conductivity of CNTs,effectively solving the problem of instability of CNTs in aqueous dispersions,which showing great potential for the application of hybrid materials in the development of conductive inks and electronic component printing.