| Abstract [eng] |
Carbonated calcium phosphates are promising materials due to their chemical similarity to biological apatites and potential for biomedical applications. However, their carbonated analogues remain insufficiently investigated. The aim of this master’s thesis was to synthesize carbonated hydroxyapatite (CHA) and carbonated fluorapatite (CFA) using the microwave–assisted synthesis and to determine their main properties. Calcium phosphates were synthesized in aqueous suspensions containing calcium carbonate and phosphoric acid or calcium carbonate, phosphoric acid, and ammonium fluoride. The initial components were mixed to correspond to the stoichiometric composition of hydroxyapatite (Ca:P = 10:6) and fluorapatite (Ca:P:F = 10:6:1). Microwave–assisted synthesis was carried out in 30 mL borosilicate vials placed in a “Monowave 300” microwave reactor at temperatures ranging from 100 to 200 °C for 2 hours. It was determined that at 100 °C, CHA formed together with octacalcium phosphate pentahydrate, while unreacted calcium carbonate remained in the synthesis products. With increasing synthesis temperature, CHA became the predominant phase with only minor calcium carbonate impurities. During CFA synthesis in the temperature range of 100–160 °C, the target product predominated in the synthesis products, while the amount of unreacted calcium carbonate decreased with increasing temperature. The most favorable synthesis conditions were established at 160 °C, where the yields of CHA and CFA reached 92.40% and 92.42%, respectively, while the crystallite sizes were 59 nm and 76 nm. It was observed that CHA particles exhibit a hexagonal rod–like and irregular plate–like morphology, with particle sizes distributed over a wide range (0.47–104.71 μm). In contrast, CFA particles were characterized by smaller sizes (0.47–69.18 μm) with elongated and rounded morphology. It was determined that synthetic carbonized apatite particles tend to form agglomerates. Thermal analysis results showed that CFA exhibited higher hygroscopicity, as the mass loss of adsorbed water reached 4.63%, compared to 1.81% for CHA. Antibacterial activity tests revealed that CHA did not exhibit antibacterial effects against the investigated microorganisms, whereas CFA effectively inhibited the growth of S. aureus and E. coli bacteria. Synthetic products were used for the fabrication of PLA and 20 wt.% apatite (CHA/CFA) composite 3D scaffolds with a gyroid structure. The results showed that the fillers were uniformly distributed within the polymer matrix, while the fabricated PLA–CHA and PLA–CFA scaffolds exhibited Young’s modulus values of 111.46 ± 8.97 MPa and 106.20 ± 7.35 MPa, respectively, indicating their potential for bone tissue regeneration applications. |
