Composition and physicochemical properties of copper-modified hydroxyapatite obtained by the liquid-phase method under microwave exposure

The paper considers the regularities in the change in the elemental and phase composition of the obtained samples of copper-modified hydroxyapatite from the content (mol) of copper ions (0.01; 0.025; 0.05; 0.075; 0.1) taken in the initial solutions. The need to modify hydroxyapatite and other calcium phosphates with copper ions is due to the high risk of infections at the sites of operations to replace bone tissue with implants based on calcium phosphates and the refusal to use antibiotics. Qualitative and quantitative phase composition, elementary cell parameters of all phases were determined for the obtained crystalline powders by X-ray phase analysis. The main phase in all samples is HA[Ca5(PO4)3OH], and the impurity phases are calcium and copper phosphates. It is noted that the elementary cell parameters of HA do not change when modified with copper ions. The quantitative assessment of the elemental composition, including copper, of the surface of the synthesized CuHA samples was carried out by X-ray spectral microanalysis, and the morphology was studied by scanning electron microscopy. According to the results of these methods, the atomic ratio (Ca+Cu)/P in the modified samples is approximately 1.8, which is in the range of values for biogenic hydroxyapatite. The solubility of the obtained CuHA powders in a 0.9% (wt.) solution of sodium chloride at 25°C was evaluated based on the results of complexometric titration of calcium ions in saturated solutions. The solubility of the obtained samples is commensurate with the solubility of HA. To study the antibacterial activity of CuHA samples and compare them with HA, biotesting by the Koch method against Staphylococcus aureus (S. aureus) was carried out. Samples of CuHA showed antibacterial activity of low intensity. The authors express their deep gratitude to Dmitry Fedorishin, Junior Researcher, Laboratory for Research and Application of Supercritical Fluid Technologies in Agro-Food Biotechnologies, Tomsk State University, for assistance in conducting biological studies and interpreting the results. Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.

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