Hydroxyapatite (HA) powders were synthesized by the wet precipitation method in which two experimental compositions were synthesized (10 mol% Ag-HA and Cu-HA)where the CaNO 3 content was partially substituted with AgNO 3 and Cu(NO 3 ) 2 .X-ray diffraction (XRD) was employed to characterize changes to the HA structure as the dopants (Cu 2+ , Ag + ) were incorporated into the materials structure. Energydispersive X-ray spectroscopy (EDS) determined confirmed the compositions and found that the Ca/P ratio was 1.63 for the control (HA) while Ag-HA and Cu-HA exhibited (X + Ca)/P ratios of 1.79 and 1.65, respectively. Antibacterial efficacies were evaluated against E. coli and S. aureus, as a function of surface area and incubation time. The more prominent antibacterial effects were observed with both Ag-HA and Cu-HA and the materials antibacterial influence was maintained with respect to time. Ion release studies of each HA composition (15, 30, and 45 days) showed that Cu-HA released significantly more Cu 2+ (36.1 ± 5.1 mg/L) than Ag + (2.9 ± 1.2 mg/L) from Ag-HA. Analysis of each composition incubated in simulated body fluid (SBF) exhibited surface depositions that are likely calcium phosphate (CaP). Cytocompatibility testing in MC 3T3 Osteoblasts showed slight reductions in cell viability when tested using MTT assay, however cell adhesion studies were positive for each composition.

This review focuses on the advances made in the synthesis and application of hydroxyapatite (HA)-and β-tricalcium phosphate (β-TCP)-based composites for biomedical purposes, with focuses placed on both laboratory exploration and clinical translation. First, polymeric matrix materials are reviewed, with comparisons between naturally-and synthetically-derived polymers briefly introduced. Second, calcium phosphates used in hard tissue replacement are broadly reviewed, with primary distinctions between HA and β-TCP discussed. A wide range of HA-and β-TCP-polymer composites for various applications are then reviewed extensively, with both biological and mechanical properties emphasized, along with the various fabrication methods that have been developed. Finally, clinically implemented composites are surveyed, with commercially available products and their respective uses highlighted.

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