Influence of hydroxyapatite nanoparticle shape on carrier concentration and its role in osteosarcoma cell inhibition

Abstract In this study, two distinct hydroxyapatite nanoparticle (HAp) shapes—nanospheres and nanorods—were synthesized and evaluated for their influence on cytotoxicity and photocatalysis using MG63 osteosarcoma cells. The standard chemical precipitation process was used to create the hydroxyapatite nanospheres, while polyvinyl alcohol was used as a capping agent to create the nanorod forms. The characteristic features of the fabricated hydroxyapatite nanoparticles (HAp) were examined with X-ray diffraction (XRD) analysis, Raman spectroscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence (PL). Also, high-resolution transmission electron microscopy (TEM) images and positron annihilation lifetime spectroscopy (PALS) were used to understand the relationship between the defects in hydroxyapatite (HAp) samples and the photodegradation of the MB dye. The interfacial charge-transfer behavior for each sample in an electrolyte was characterized by Mott–Schottky and electrochemical impedance. Also, the carrier density and conductivity of the manufactured materials and lattice structures were observed in two shapes, confirming the crystalline nature of the nanoparticles. To assess cytotoxicity, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed using the osteosarcoma cell line (MG63). Nanorod particles exhibited higher cytotoxicity than nanospheres, as the application of nanotechnology starts to be an effective tool in cancer treatment. The outcomes of the current study may assist in the shape design of hydroxyapatite nanoparticles for therapeutic applications such as drug delivery vehicles in nanomedicine. It highlights the strong correlation between the electrochemical impedance and the cytotoxicity of the hydroxyapatite (HAp) samples, elucidating the role of charge carriers in cytotoxicity and photocatalytic degradation, initiating the redox reaction which releases the toxic reactive species selectively within osteosarcoma cells, resulting in the destruction of cancer cells while sparing normal cells, and demonstrating how physical and electrical characteristics impact a range of applications. Graphical Abstract