Biogenic hydroxyapatite-based composites modified by magnetite and chitosan: long-term bioresorption and adsorption activity

The work is devoted to the investigation of the long-term resorption of BHA/magnetite/chitosan composites with a magnetite content of 1, 5, 25, and 50 wt.% in physiological solution for different periods of time (2, 10, 16, and 31 days) and their adsorption activity toward methylene blue. It was shown that the content of magnetite significantly affects the rate of resorption of materials, in particular at the initial stages; the highest rate of resorption is observed during the first 2 days. In the next 8-10 days, a sharp decrease in the rate of resorption of all composites is observed, followed by stabilization on the 15th day of the in vitro experiment. At the same time, the most significant weight loss of test samples occurs when added more than 5 wt. % of magnetite. The dynamics of the dissolution process is also confirmed by the presence of Ca, P and Fe in physiological solution, a change in the pH of the saline, a decrease in the size and smoothing of composite particles, and an increase in the specific surface area. The adsorption activity for methylene blue increases with increasing amounts of chitosan and magnetite in the composites up to 168 mg/g for 25% magnetite (2.5% chitosan) compared to 108 mg/g for pure BHA. The obtained results confirmed the controlled resorption and high adsorption properties of BHA/magnetite/chitosan composites, which provides prospects for their medical application.