Physico-chemical and in vitro biological study of zinc-doped calcium sulfate bone substitute.

In the present study, series of Zn incorporated calcium sulfate bone cements, with different amounts of doped Zn(0, 0.74, 1.97, 3.05, 4.21 wt %) were prepared by mixing a calcium sulfate hemihydrate powder and solutions of zinc sulfate, and the effect of zinc-doping on some physical, physico-chemical, and biological properties of the cements were investigated. Pure calcium sulfate cement was also made as control, with the mentioned powder and distilled water as liquid phase. The initial setting time and compressive strength of the cement significantly changed from 17 min and 3.2 MPa for the pure calcium sulfate to 6 min and 6 MPa for the Zn-added calcium sulfate, respectively. Compared to pure calcium sulfate, more gypsum precipitates were formed in the zinc sulfate added samples with a morphology of thin, elongated, and rod-shaped crystals. The biological properties of the samples were analyzed in the terms of cell viability and cell activity on human osteosarcoma (G-292) using MTT assay and alkaline phosphatase (ALP) activity in the cell culture medium. The best increased cell density and ALP activity were achieved for the calcium sulfate cement with a content of 0.74 wt % Zn, whereas a toxic behavior was observed for the samples with Zn concentrations more than 1.97%.