Proteomic evaluation of borosilicate hybrid sol-gel coatings with osteogenic, immunomodulatory and antibacterial properties

Abstract

Silica hybrid sol-gel coatings represent an interesting approach to bioactivate dental implants. Boron is known for its osteogenic, angiogenic and antibacterial functions in biomedical applications. This study describes the synthesis of a novel borosilicate hybrid sol-gel coating using a mixture of methyltrimethoxysilane, tetraethyl orthosilicate and trimethyl borate (TMB). Coatings with different amounts of boron were obtained, and their physiochemical properties were examined; in vitro tests with human osteoblasts and macrophages (THP-1) were carried out. The effects of these materials on bacteria viability were evaluated using Escherichia coli and Staphylococcus aureus. The human serum proteins adsorbed onto the coatings were analysed employing proteomic techniques. To synthesise the new materials, the appropriate sol-gel reactions were developed; boron was integrated into the silica network, and well-adhering coatings were obtained. These borosilicate coatings were non-cytotoxic, displayed osteogenic potential, and upregulated adsorption of proteins related to bone regeneration (IGF2, ALS and APOE). Boron upregulated the expression of TNF-α, INFg and TGF-β and increased the TNF-α and TGF-β cytokine production in THP-1. Moreover, the addition of boron caused downregulation of NOX2 expression. Proteomic analysis revealed that boron-doping reduced the adsorption of immunoglobulins and complement system proteins. It also caused an increase in the levels of apolipoproteins, antioxidant proteins and serum amyloid A proteins, which was in agreement with in vitro results. The coatings with 10 and 20 % TMB displayed antibacterial effect against S. aureus. The results of this study will enhance our comprehension of interactions between boron-containing biomaterials and biological systems.