Design and construction of a microporous CO 3 2 − -containing HA/β-TCP biphasic ceramic as a novel bone graft material

Abstract Biphasic calcium phosphate (BCP) ceramics, viewed as the first-line therapeutic materials in clinical practice, are still confronted with challenges such as undesirable biocompatibility and bioactivity given their structural and chemical deficiency. In this study, we designed a novel microporous {{CO}₃}²⁻-containing BCP ceramic from Salmo salar bone in a CO₂ atmosphere via two-step high-temperature sintering, and its physicochemical properties and biocompatibility were explored. A without {{CO}₃}²⁻- BCP bioceramic material prepared in a single gas atmosphere was used as a comparison. The two scaffolds were characterized by x-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) , measured the size of its porosity and specific surface area by an instrument and in vitro cell experiment was used to test its biocompatibility. Such synthetic strategy endowed the BCP products with increased β-tricalcium phosphate (β-TCP) percentage from 37.18wt% to 45.3wt% (compared to BCP without {{CO}₃}²⁻), with the {{CO}₃}²⁻ content calculated to be 1.98wt%, which is close to that in human bone tissue. The amount of {{CO}₃}²⁻ incorporation, the a-axes of the lattice parameters have decreased significantly from 9.4845 nm to 9.2942 nm by Rietveld structure refinement. Especially, the novel {{CO}₃}²⁻ containing BCP exhibits a lower degree of crystallinity than that without CO3^2-. In addition, the natural microporosity remarkably increased from 49.6% for BCP without {{CO}₃}²⁻ to 64.06% for {{CO}₃}²⁻-containing BCP, and the specific surface area increased from 5.829 m²g⁻¹ to 17.161 m²g⁻¹. Besides, two materials were non-toxic to human bone marrow mesenchymal stem cells (hBMSCs), and the {{CO}₃}²⁻ -containing BCP had more factor expression in the early stage of osteogenesis induction, such as Runx2 and Smad 4. Overall, microporous {{CO}₃}²⁻-containing BCP were prepared via a simple preparation method from natural bone, combining the structural and chemical preponderance, as well as in vitro performance it should be considered as a promising biomaterial for further explorations in the fields of bone graft materials from natural bone to satisfy versatile clinical requirements.