Chemical Stability, Morphological Behavior of Mg/Sr-hydroxyapatite@chitosan Biocomposites for Medical Applications

Long-term biocompatible scaffolds based on chitosan (CS) encapsulated with hydroxyapatite (HAP) have been developed for orthopedic applications. The biocomposites consisting of magnesium (Mg)/strontium (Sr) co-dopant into HAP@CS were fabricated using a casting technique, whereas Mg(II) contribution was varied. The crystal growth seems to be in the c-axis upon the rising of Mg(II) content, whereas the c/a ratio changed from 0.72 to 0.73. Moreover, it was suggested that Mg(II) ions prefer to substitute Ca(1) rather than Ca(2) sites within HAP crystals. The study of morphology indicated that the Mg/Sr-HAP was formed as agglomerated grains with dimensions around 5.1-9.2, 6.2-11.4, 3.6-7.3, 3.1-18.3, and 6.1 - 18.3 mu m, while the grains of CS were developed as 4.6-7.6, 3-14.3, 2.4-6.1, 9.1-30.5 and 6.2-9.1 mu m for 0.0Mg/Sr-HAP@CS, 0.2Mg/Sr-HAP@CS, 0.4Mg/Sr-HAP@CS, 0.6Mg/Sr-HAP@CS, and 0.8Mg/Sr-HAP@CS, respectively. Moreover, the roughness average (R-a) raised from 37.3 to 48.4 nm for the minimum and the highest additional Mg(II). Furthermore, the compressive strength was investigated and exhibited that Mg(II) has induced high resistance to fracture, whereas compressive strength increased from 7.17 +/- 1.1 to 15.1 +/- 1.5 MPa for the highest Mg(II). The cell viability also was tested, and the high value (105.2 +/- 6.8%) was achieved for the highest Mg(II). Finally, the corrosion behavior for the scaffolds through simulated body fluids was investigated and illustrated that the corrosion potential (E-corr) was shifted to positive values from -0.14 to -0.002 V upon the variation of Mg(II) content. (C) 2022 The Authors. Published by Elsevier B.V.