Pulsed electrodeposition of MXenes/HAp multiple biological functional coatings on 3D printed porous Ti-6Al-4V bone tissue engineering scaffold

Titanium and its alloys have been widely used as bone tissue engineering scaffold due to their excellent biocompatibility and mechanical strength. In order to promote bone ingrowth, integration and match the mechanical properties of natural bone tissue, this study proposed diamond-like microstructure porous Ti-6Al-4V scaffolds for personalized bone defect repair. In order to prepare the multiple biological functional coatings on the curve surface inside of the 3D printed porous scaffolds, pulsed electrodeposition method was proposed to obtain multiple layers of Ti3C2Tx/HAp composited coatings. Delaminated Ti3C2Tx has an ultra-thin microstructure according to transmission electron microscopy (TEM) observation and is well dispersed in electrolyte. X-ray diffraction (XRD) characterization shows that Ti3C2Tx has been synthesized and regulates more CaHPO4‧2H2O (DCPD) to Hydroxyapatite (HAP) conversion, which is confirmed by Fourier transform infrared spectroscopy (FTIR) at 0.2 mg/mL concentration. Scanning electron microscopy (SEM) shows that the morphologies of composite coatings are closely related to Ti3C2Tx content due to the availability of effective voltages for electrodeposition. By means of finite element method, deposition thickness and distribution of coatings were simulated to explore the precipitation kinetics and selection of electrodeposition parameters and a current density of 15 mA/cm2 was ultimately used. In vitro electrochemical corrosion of Ti3C2Tx/HAp coatings were tested in human simulated body fluid (SBF) to verify its corrosion resistance in physiological environment and Ti3C2Tx/HAp composited coatings possess the best corrosion resistance according to linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) tests. In vitro MC3T3-E1 cell culturing studies were investigated to evaluate cell behaviors and biocompatibility of these coatings. The results indicate that cells grow well on the surface of composite coatings without showing cytotoxicity and cell morphologies show a good spreading state and a trend of inward growth.