Biosynthesis of Calcium Oxide Nanoparticles Using Jatropha tanjorensis Leaf Extract and the Evaluation of its Antibacterial Efficacy Against Multidrug Resistance Uropathogens and Haemocompatibility

Abstract

The biosynthesis of metal oxide nanoparticles using phytochemicals from plant extracts has been recognized as a sustainable, low-toxicity alternative to chemically synthesized antimicrobials. It provides an environmentally friendly approach to combat the growing burden of multidrug-resistant (MDR) pathogens. This study investigates the biosynthesis of calcium oxide nanoparticles (CaONPs) using aqueous leaf extract of Jatropha tanjorensis, an indigenous Nigerian medicinal plant rich in phytochemicals capable of chelating and reducing Ca²⁺ ions, and evaluates their antibacterial and haemocompatibility profiles against pathogens isolated from urine samples. CaONPs were synthesized by combining CaCl₂ solution with the leaf extract under alkaline conditions, followed by centrifugation and calcination at 700 °C. The nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Antibacterial activity was assessed against four uropathogenic isolates, Klebsiella pneumoniae, Proteus mirabilis, Bacillus cereus and Staphylococcus aureus, using agar diffusion and broth microdilution to determine MIC and MBC. Biocompatibility was evaluated using a haemolytic assay on human erythrocytes. Characterization confirmed nanoparticle formation, phytochemical capping, heterogeneous surface morphology and particle dimensions within the nanoparticle size range. All isolates showed concentration-dependent bactericidal activity, with MIC and MBC values ranging from 1.88–3.75 µg/mL for P. mirabilis and 7.50–15.00 µg/mL for the remaining isolates, with inhibition zones of 15.20–22.00 mm. Haemolytic assays showed a favorable safety margin, with an estimated LC₅₀ of 436.973 µg/mL, indicating minimal haemolytic activity within the effective antibacterial range. These findings position J. tanjorensis-mediated CaONPs as promising, biocompatible option for topical or catheter-coating antimicrobial applications.