Doping effects of Pd2+ on physicochemical and biomechanical properties of calcium silicate in nano-regime towards treating osteoporotic bone

Abstract

Fully dense biphasic calcium silicates with improved biomechanical behavior were fabricated via mechanothermal method followed by the conventional sintering process. The effects of dopant concentration on the phase composition, structural evolution, and mechanical properties of palladium-doped calcium silicates (PCSs) were investigated. The results showed that the coalescence of nanoparticles, coarsening of particles, and the formation of large agglomerates occurred during the mechanothermal reactions. Attenuated total reflection (ATR) spectroscopy spectra of the PCSs represented the characteristic bands of the calcium silicates, including the bending mode of Si–O–Si and O–Si–O, the stretching vibration of O–Si–O group, the stretching mode of Si–O–Ca, as well as the symmetrical stretching mode of Si–O–Si group. The results of the Rietveld refinement indicated that the phase compositions and structural features noticeably affected by the dopant concentration so that the phase fraction (PF) of Wollastonite-1A and Pseudowollastonite was 0.318 ± 0.035 and 0.526 ± 0.025 in the case of undoped calcium silicate (PCS0), which respectively reached 0.411 ± 0.021 and 0.589 ± 0.021 for the Pd-doped calcium silicate (PCS20). Comparing with the PCS0, the Vickers hardness of the consolidated PCS20 increased by ~79%. From the biomineralization analysis, the surface of the consolidated sample was covered by the bone-like apatite after soaking in a simulated body fluid (SBF) for 2 weeks.