Enhanced bioactivity and interfacial bonding strength of Ti3Zr2Sn3Mo25Nb alloy through graded porosity and surface bioactivation

Abstract

ABSTRACT The gradient porous Ti3Zr2Sn3Mo25Nb (TLM) alloy rods were fabricated through sintering the alloyed powder to a solid core. The porous sample was then modified by a Micro Arc Oxidation (MAO) treatment in an electrolyte containing calcium and phosphate, a hydrothermal treatment enabled secondary microporous hydroxyapatite (HA) coating, and a further bone morphogenetic protein-2 (BMP-2) loading treatment through immersion and freeze-drying. The treatment led to an orderly secondary microporous coating containing HA nano-particles and evenly distributed BMP-2 in the porous coatings. As a result, osteoblasts could adhere and grow well on the coatings with a high cell adhesion rate and cell functional activity. The in-situ shear testing indicated that the interfacial strength had been enhanced significantly. Improvement of the bond formation and osseointegration with the titanium implant is attributed to increased surface area for the cell to attach, creating voids for the cell to grow in, and activating titanium surface by introducing bioactive ingredients such as HA and BMP-2.