Combined Hydrothermal Conversion and Vapor Transport Sintering of Ag-Modified Calcium Phosphate Scaffolds


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Two processing methods were successfully combined to obtain Ag-modified calcium phosphate scaffolds with antibacterial properties: (i) hydrothermal conversion of macroporous biogenic carbonates and (ii) vapor transport sintering. Hydrothermal conversion of two precursor materials, i.e., coral skeletons and sea urchin spines, resulted in the pseudomorphic replacement of highly porous calcium carbonates by calcium phosphate scaffolds. Vapor transport sintering of these scaffolds within a reactive AgCl atmosphere facilitated near net-shape processing accompanied by the condensation of finely dispersed Ag-bearing particles over the scaffold's surface. Chemical and phase compositions were analyzed using WDXRF, XRD, and DRIFTS (FTIR), and the microstructure development was characterized by SEM and TEM imaging. The dissolution kinetics of Ag+ ions in aqueous solution was determined and growth inhibition experiments with Gram-positive and Gram-negative bacteria were performed to assess the antibacterial properties of Ag-modified ceramics.