Cytocompatibility of Ti₃AlC₂, Ti₃SiC₂, and Ti₂AlN: In Vitro Tests and First-Principles Calculations

Herein, the cytocompatibility of selected MAX phases, Ti₃AlC₂, Ti₃SiC₂, and Ti₂AlN, were systematically evaluated using in vitro tests for the first time. These phases were anoxic to preosteoblasts and fibroblasts. Compared with the strong viable fibroblasts, the different cellular responses of these materials were clearly distinguishable for the preosteoblasts. Under an osteoblastic environment, Ti₂AlN exhibited better cell proliferation and differentiation performance than Ti₃AlC₂ and Ti₃SiC₂. Moreover, the performance was superior to that of a commercial Ti-6Al-4V alloy and comparable to that of pure Ti. A possible mechanism was suggested based on the different surface oxidation products, which were determined from the binding energy of adsorbed Ca²⁺ ions using first-principles calculations. Compared with the partially oxidized TiC_xO_y layer on Ti₃AlC₂ and Ti₃SiC₂, the partially oxidized TiN_xO_y layer on the Ti₂AlN had a stronger affinity to the Ca²⁺ ions, which indicated the good cytocompatibility of Ti₂AlN.