Synthesis, characterization, and antimicrobial properties of strontium-substituted hydroxyapatite

Ion-substituted hydroxyapatite (HAP) offers several advantages compared with pure HAP. Since the calcium amount is relatively lower compared with the stoichiometric ratio of pure HAP, the resulting calcium deficiency in ion-substituted HAP leads to higher degradation in the physiological environment. Therefore, ion-substituted HAP has promising applications in the biomedical industry, particularly in drug delivery systems. In the present work, strontium-substituted HAP (Sr-HAP) was prepared by wet chemical precipitation method. The powders were characterized by X-ray diffraction (XRD) method and scanning electron microscopy (SEM). The crystallite size of Sr-HAP was calculated as approximate to 9 nm. Furthermore, structural characterization of Sr-HAP was done by Rietveld refinement and the substituting atomic sites and occupancies were obtained. The atomic positions occupied by the substituted Sr atoms in the calcium (Ca) atomic positions in thehcpunit cell were identified. The unit cell parameters of synthesized Sr-HAP were precisely calculated. The synthesized Sr-HAP powders were compacted and the antimicrobial properties were assessed by usingEscherichia coli(E. coli) andSporosarcina pasteurii(S.pasteurii). From the antimicrobial studies, it was understood that Sr-HAP has shown lower viability of these strains compared with pure HAP which is an indication of antimicrobial properties of Sr-HAP.