No abstract

Resorbable calcium phosphate (CaP)‐based biomaterials are important because they can significantly improve health care by shortening the time necessary for restoration of functional loading of grafted bones. Although synthetic CaPs show exceptional similarities to natural bone, however, they are deficient in one major area, in that they do not have the same mineral content of bone. The focus of our work is to understand the influence of dopants on the physical, mechanical, and biological properties of tricalcium phosphate (TCP) resorbable ceramics with special emphasis toward in vitro strength degradation and cell–materials interactions as a function of time. For this purpose, β‐TCP was doped with magnesia (MgO), zinc oxide (ZnO), and silica (SiO2). Those dopants were added as individual dopants, and their binary and ternary compositions. It was found that these dopants significantly influenced densification behavior and as sintered microstructures of TCP. In vitro mineralization studies in simulated body fluids (SBF) for 12 weeks showed apatite growth on the highly porous compositions either on the surface or inside. From scanning electron microscopic analysis it was evident that surface degradation occurred on all compositions in SBF. Compression strengths for samples up to 12 weeks in SBF showed that it is possible to tailor strength loss behavior through compositional modifications. The highest compression strength was found for binary MgO–ZnO doped TCP. Overall, samples showed either a similar strength level during the 12 weeks test period, or a continuous decrease or a continuous increase in strength depending on dopant chemistry or amount. In vitro human osteoblast cell culture was used to determine influence of dopants on cell‐materials interactions. All samples were non‐toxic and biocompatible. Dopant chemistry also influenced adhesion, proliferation, and differentiation of osteoblastic precursor cell line 1 (OPC1) cells on these matrices.

The purpose of this study is to prepare tricalcium phosphate (TCP) ceramic by dual dopants of magnesium (Mg) and zinc (Zn), and investigate the influence of dopants on the physical, mechanical and biological properties of TCP. TCP were synthesized with 1 wt% Mg, 0.3 wt% Zn and dual dopants using the precipitation process. Phase composition and microstructures were characterized. Mechanical properties and dissolution behavior in vitro were investigated. Human osteoblast cell culture was used to determine the influence of dopants on cell-materials interactions. XRD analysis indicated that Mg delayed phase transformation from beta to alpha-TCP and pure beta-TCP phase was obtained for Mg-doped TCP after sintered at 1250 degrees C. Addition of Mg improved densification behavior of TCP. Compression strength also increased from 24.0 MPa to 77.2 MPa after doping with Mg and Zn. Furthermore, Mg additive reduced the solubility of TCP in vitro. Osteoblast culture studies indicated that the presence of Mg stabilized the cell-material interface and thus improved cell attachment and growth. Zn-doped TCP exhibited good bioactivity, which enhanced cell differentiation and alkaline phosphatase (ALP) expression. The highest cell proliferation and ALP expression were found on dual Mg and Zn doped TCP. The results indicate that Mg and Zn dopants play a significant role towards improving mechanical properties and cell-materials interactions of TCP. This work also demonstrates the potential for dual Mg and Zn doped TCP to be used in orthopedics and dentistry, which displays high mechanical strength, low resorption and improved cell-material interaction.

No abstract

The objective of this study was to investigate the in vitro bioactivity of strontium-containing hydroxyapatite (Sr-HA), and its effect on cellular attachment, proliferation, and differentiation. The effect of Sr-HA has been compared with that of hydroxyapatite (HA), which is widely used in orthopedics and dentistry. Sr-HA ceramic containing 10 mol % was prepared. The bioactivity of Sr-HA was evaluated in vitro by immersion in simulated body fluid (SBF). After immersion in SBF, Sr-HA exhibited greater ability to induce apatite precipitation on its surface than did HA. The possible effects on cell behavior of Sr-HA were examined by culturing osteoprecursor cells (OPC1) on materials surfaces. Cell shape and cell-material interactions were analyzed by scanning electron microscope (SEM) and the MTT assay was used to determine cell proliferation on samples. When compared with HA, Sr-HA promoted better OPC1 cell attachment and proliferation, and showed no deleterious effects on extracellular matrix formation and mineralization. Confocal scanning microscopy was used to assess the expression of specific osteoblast proteins: alkaline phosphatase (ALP) and osteopontin (OPN). The results obtained indicate that the presence of Sr stimulates OPC1 cell differentiation, and enhances ALP and OPN expression.