Comparative evaluation of hydroxyapatite synthesized using Plectranthus amboinicus and Sesbania grandiflora: Structural characteristics, antibacterial performance, and cytocompatibility

The current study compares the plant-mediated synthesis of hydroxyapatite (HAp) using extracts of Sesbania grandiflora and Plectranthus amboinicus as green mediators to investigate their influence on the structural and biological properties. HAp, Plectranthus amboinicus -mediated HAp (PHAp), and Sesbania grandiflora -mediated HAp (SHAp) were synthesised by a wet chemical method. The HAp samples prepared with and without plant extracts were characterised to examine the influence of plant mediators. FT-IR characterisation shows that the functional groups correspond to HAp. XRD analysis indicated that HAp is the predominant crystalline phase with a hexagonal structure in both plant extract-mediated and non-mediated samples. Scherrer analysis indicated that PHAp exhibited the smallest apparent crystallite size among the samples. In contrast, SHAp demonstrated a higher degree of crystallinity. SEM analysis showed that the use of plant extracts resulted in less agglomerated and more uniformly distributed particles, with PHAp displaying finer morphology than SHAp. EDAX shows a Ca/P ratio close to the stoichiometric value. The antibacterial performance of HAps shows that PHAp exhibited superior antibacterial activity against Escherichia coli and Staphylococcus aureus compared to SHAp and HAp. Both PHAp and SHAp showed high cell viability (>90%) indicating favorable cytocompatibility and low cytotoxicity. Plant-mediated synthesis can effectively tailor the structural and biological properties of HAp. PHAp showed enhanced antibacterial performance and cytocompatibility, whereas SHAp exhibited higher crystallinity, highlighting the potential of both materials as promising candidates for further investigation in bone-related biomedical applications.