Low-temperature fabrication of titania layer on 3D-printed PEKK for enhancing biocompatibility

Abstract

Bioactive titania layer in petal-like nanostructures was fabricated on 3D-printed polyetherketoneketone (PEKK) substrate through two-step method at low temperature. As connected step, sulfonation processing was adopted to induce the hydrophilic -SO3H groups on the surface of PEKK sample. These negatively charged -SO3H groups were considered as multiple nucleation sites for in-situ self-assembly of titania layer in subsequent treatment. After being immersed in the precursor solution (TiOSO4/HNO3/H2O2) at 100 °C, the sulfonated PEKK sample were surrounded by TiO2+ species due to the electrostatic interactions. At the initial stage of the hydrothermal reaction, a lower degree of supersaturation with TiO62− octahedron was achieved by the slow hydrolysis of TiO2+, which favored the heterogeneous nucleation of rutile TiO2 nanostructures on the substrate. At the growth stage, rutile TiO2 nanoneedles had the preferred orientation of the [001] direction. {101} needle-tip facets with high surface energy were served preferentially as nucleation sites for further growth of TiO2 crystal, which finally gave rise to petal-like structures composed of nanoneedles. After soaking in 1.5 times simulated body fluid (1.5SBF) solution for 3 days, calcium-deficient apatite layer was induced on ST-PEKK. The results of cell experiments demonstrated that the cell viability of MC3T3-E1 cells and BMSCs on ST-PEKK sample was better than that of PEKK sample, which meant that the obtained titania layer in petal-like nanostructures was conducive to cell adhesion and proliferation. In a word, this two-step method was expected as a novel approach to improve the biocompatibility of the 3D-printed customized PEKK.