Microstructure enhanced biocompatibility in laser additively manufactured CoCrMo biomedical alloy.

ABSTRACT

The present work investigated biocompatibility of the unique nanostructural surface morphology inherently evolved in laser-based additively manufactured CoCrMo after biocorrosion in simulated body fluid at physiological temperature (37 °C). The extremely rapid thermokinetics intrinsically associated with the laser-based additive manufacturing technique resulted in heterogeneous cellular dendritic solidification morphologies with selective elemental segregation along the cell boundaries within CoCrMo samples. Consequently, a selective and spatially varying electrochemical response resulted in generation of a nanoscale surface morphology (crests and troughs) due to differential localized electrochemical etching. Also, depth of the trough regions was a function of the applied potential difference during potentiodynamic polarization which resulted in samples with varying morphological ratio (depth of trough/width of cell wall). CoCrMo with such nanoscale surface undulations were proposed for enhanced biocompatibility in terms of viability, spreading, and integration of MT3C3 pre-osteoblasts cells elucidated via MTT assay, immunofluorescence, and microscopy techniques. Furthermore, the influence of the morphological ratio, characteristic to the additively deposited CoCrMo after electrochemical etching (biocorrosion) on biocompatibility of MT3C3 pre-osteoblasts cells was qualitatively and quantitatively compared to a mirror-polished flat CoCrMo surface.