The controllable lanthanum ion release from Ca-P coating fabricated by laser cladding and its effect on osteoclast precursors

Abstract

Several studies have suggested that rare earth oxides can improve properties of bioceramic coating, and bone resorption of osteoclast can be inhibited by rare earth ion releasing certain concentration. However, the effects of lanthanum ion (La3+) released from Ca-P coating on osteoclast precursors is not clear. In this work, La2O3-doped gradient bioceramic coatings were fabricated on Ti alloy (Ti-6Al-4V) by laser cladding with mixed powders of CaHPO4·2H2O, CaCO3 and La2O3. And the bioactivity, mechanical properties and the La3+ release from coating were investigated in vitro. Human osteosarcoma cells (MG63) were used as a cell model to evaluate the biocompatibility of coatings. Mouse macrophage RAW264.7 cells were cultured on coatings to study the effect of La3+ release from Ca-P coating on osteoclast precursors. The XRD results reveal that the amount of HA + TCP reaches maximum (2θ = 32–33°) when the content of La2O3 is 0.6 wt%, and the proliferation of MG63 cells is up to highest value, which indicates that compared with other groups, the bioceramic coating with 0.6 wt% La2O3 is of best biocompatibility. Furthermore, the differentiation of RAW264.7 cells into osteoclast could be inhibited by controllable releasing La3+ from Ca-P coating when soaked in SBF, which demonstrates that controllable La3+ release from Ca-P coating is an effective method to prevent osteoclast formation. And a prospective therapy is provided to cure the disease of wear debris in replacement of artificial joint.