Hemocompatibility and Preangiogenic Attributes of SiBxCyNzOm Coatings for Biomedical Applications

Abstract

In current clinical practices related to orthopedics, dental, and cardiovascular surgeries, a number of biomaterial coatings, such as hydroxyapatite (HAp), diamond-like carbon (DLC), have been used in combination with metallic substrates (stainless steel, Ti6Al4V alloy, etc.). Although SiBCN coatings are widely explored in material science for diverse applications, their potential remains largely unexplored for biomedical applications. With this motivation, the present work reports the development of SiB_xC_yN_zO_m coatings on a Ti6Al4V substrate, employing a reactive radiofrequency (RF) magnetron sputtering technique. Three different coating compositions (Si_0.27B_0.10C_0.31N_0.07O_0.24, Si_0.23B_0.06C_0.21N_0.22O_0.27, and Si_0.20B_0.05C_0.19N_0.20O_0.35) were obtained using a Si₂BC₂N target and varying nitrogen flow rates. The hydrophilic properties of the as-synthesized coatings were rationalized in terms of an increase in the number of oxygen-containing functional groups (OH and NO) on the surface, as probed using XPS and FTIR analyses. Furthermore, the cellular monoculture of SVEC4-10 endothelial cells and L929 fibroblasts established good cytocompatibility. More importantly, the coculture system of SVEC4-10 and L929, in the absence of growth factors, demonstrated clear cellular phenotypical changes, with extensive sprouting leading to tube-like morphologies on the coating surfaces, when stimulated using a customized cell stimulator (StimuCell) with 1.15 V/cm direct current (DC) electric field strength for 1 h. In addition, the hemocompatibility assessment using human blood samples revealed clinically acceptable hemolysis, less erythrocyte adhesion, shorter plasma recalcification, and reduced risk for thrombosis on the SiB_xC_yN_zO_m coatings, when compared to uncoated Ti6Al4V. Taken together, the present study unambiguously establishes excellent cytocompatibility, hemocompatibility, and defines the preangiogenic properties of SiB_xC_yN_zO_m bioceramic coatings for potential biomedical applications.

Keywords: DC electric field stimulation; RF magnetron sputtering technique; SiBxCyNzOm coatings; biomedical applications; cellular compatibility; coculture; hemocompatibility.