Synthetic nanostructured wollastonite: Composition, structure and “in vitro” biocompatibility investigation

Abstract

This article describes an original sol-gel (template) method for the synthesis of a dispersed form of nanostructured wollastonite (CaSiO3), its gold nanoparticles (40–60 nm) functionalized form CaSiO3/Au-NPs, and its composite in the composition with 20 mass% of hydroxyapatite CaSiO3/HAp and synthetic hydroxyapatite, that are widely used in medicine for the reconstruction and regeneration of bone defects. The method provides the formation of porous silica carcass in samples with an average pore size of 100–160 nm due to the application of polymer siloxane-acrylate as a pore-forming template. The authors studied the processes of template destruction and phase formation in the composition of samples using TGA/DTA/DSC (thermogravimetric analysis/differential thermal analysis/differential scanning calorimetry), and XRD (X-ray diffraction analysis). The methods of SEM (scanning electron microscopy), low-temperature nitrogen adsorption, and mercury porosimetry were used to identify the morphology and study the structural characteristics (Sspec and Vpor, pore size distribution) for dispersed nanostructured samples based on wollastonite and hydroxyapatite. An “in vitro” model was used to study the functional activity (metabolism and cytokine production) of innate immune cells (neutrophils and macrophages) in contact with the obtained samples and to evaluate the viability of cells, the activity of ATPase activity, the number of cationic proteins, and apoptosis of cells. The study is novel for these systems and contributes to the existing knowledge on the biocompatibility for “in vivo” model, which provides a complex evaluation of the quality of wollastonite biomaterials used as grafts.