Ciprofloxacin-Loaded Composite Granules Enriched in Silver and Gallium Ions-Physicochemical Properties and Antimicrobial Activity

Various calcium phosphates (hydroxyapatite, alpha- and beta-tricalcium phosphate, and brushite) containing silver or gallium ions were synthesized via standard methods and subjected to physicochemical analysis by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffractometry (PXRD), and atomic absorption spectrometry (AAS). In the next step, the obtained calcium phosphate powders, sodium alginate, and chondroitin were used to produce composite granules. Ciprofloxacin, a broad-spectrum antibiotic that can be used in local delivery systems targeting bone tissue, was loaded into the granules. The release of silver and gallium ions as well as ciprofloxacin was then examined by inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC), respectively. The cytotoxicity of the granules was studied using a neutral red uptake (NRU) test and mouse embryonic fibroblasts. Moreover, preliminary antibacterial activity against Staphylococcus aureus and Escherichia coli was measured. The study showed that the type of calcium phosphates enriched in silver or gallium significantly affects the release profile of these ions. Biphasic calcium phosphates also have an impact on the morphology of the granules. Most of the granules turned out to be non-toxic to mammalian cells. Microbiological tests showed high antibacterial activity against both strains of bacteria.