Spinach to the Rescue: Unveiling the Antibacterial and Anticancer Potential of Biogenic Zinc-Doped Hydroxyapatite Nanoparticles

Abstract

This study reports the green synthesis of zinc-doped hydroxyapatite nanoparticles (ZnHANPs) using spinach extract as a novel bio-template. The synthesized ZnHANPs were characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). XRD analysis confirmed the crystalline nature of the ZnHANPs with an average crystallite size of 100 nm. FT-IR spectra revealed the presence of characteristic functional groups associated with hydroxyapatite. SEM and TEM images showed predominantly rod-shaped nanoparticles, a morphology advantageous for bone regeneration and targeted drug delivery. Elemental mapping confirmed the presence of Zn, Ca, P, and O. The synthesized ZnHANPs exhibited significant antioxidant activity, demonstrating a concentration-dependent increase in DPPH radical scavenging. Furthermore, the ZnHANPs displayed potent antibacterial activity against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, with greater efficacy observed against B. subtilis. Importantly, the ZnHANPs demonstrated significant anticancer activity against MCF-7 breast cancer cells. MTT assays revealed an IC₅₀ value of 46 mg/mL. Dual staining (AO/EtBr) and DAPI assays confirmed that ZnHANPs induced apoptosis in MCF-7 cells by increasing ROS production and causing DNA damage. These findings highlight the potential of green-synthesized ZnHANPs as promising candidates for biomedical applications, including bone regeneration, antibacterial agents, and cancer therapy.