Wetting effects on in vitro bioactivity and in vitro biocompatibility of laser micro-textured Ca-P coating

Calcium phosphate (Ca-P) coating on the Ti-6Al-4V alloy enhances osteoblast adhesion and tissue formation at the bone implant interface. In light of this, in the current work a laser-based coating technique was used to synthesize two different micro-textured (100 microm and 200 microm spaced line patterns) Ca-P coatings on the Ti-6Al-4V alloy and its effect on wettability and osteoblast cell adhesion were systematically studied. X-ray diffraction (XRD) analysis of the coated samples indicated the presence of precursor material, Ca10(PO4)6(OH)2 (HA) and various other additional phases such as CaTiO3, Ca3(PO4)2, TiO2 (anatase) and TiO2 (rutile) owing to the reaction between the precursor (HA) and substrate (Ti-6Al-4V) during laser processing. Confocal laser scanning microscopy-based characterization of coated samples indicated that the samples processed at 100 microm line spacing demonstrated a reduced surface roughness and smaller texture parameter value as compared to the samples processed at 200 microm spacing. The surface energy and wettability of the 100 microm spaced samples measured using a static sessile drop technique demonstrated higher surface energy and increased hydrophilicity as compared to the control (untreated Ti-6Al-4V) and the samples processed at 200 microm spacing. The tendency of coated samples for mineralization through generation of an apatite-like phase during immersion in a simulated body fluid was indicative of their in vitro bioactive nature. In light of higher surface energy and increased hydrophilicity the in vitro biocompatibility of the samples with 100 microm line spacing was demonstrated through increased cell proliferation and cell adhesion of mouse MC3T3-E1 osteoblast-like cells.