Comprehensive characterization of biocomposite surface based on the mesoporous silica and lysozyme molecules: Chemistry, morphology, topography, texture and micro-nanostructure

The results presented in this paper focus on a detailed analysis of surface composition, texture, morphology and micro-nanostructure of mesocellular silica foam (MCF) covered by the lysozyme (LYS) molecules from aqueous solutions at pH = 7.4. The physicochemical and structural properties of the LYS/MCF biocomposite were characterized by various techniques including attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FT-IR), elemental analysis (CHN), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (UVVis DRS), X-ray diffraction (XRD). Moreover, the morphology, micro-nanostructure, topography and elemental composition of biocomposite surface were determined using atomic force microscopy (AFM), optical profilometry (OP), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy with X-ray microanalysis (SEM/EDS). AFM, OP, TEM and SEM methods (with regard to morphology, topography, structure at a micro-nanometer level) demonstrate that the surface of the support with immobilized protein is less rough, porous, wavy, sharp, and hence more smooth, flat and uniform due to the proteins adsorbed on support surface. EDX and EDS demonstrated the homogeneous distribution of protein molecules on silica surface. XRD confirmed that the lysozyme molecules were located on the support surface and inside the pores, and XPS revealed the specific interactions between the albumin and silica.