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Plant Science Today (PST)

Research Articles

Vol. 13 No. 3 (2026)

Synthesis, characterisation, antibacterial and antioxidant potential of cobalt oxide nanoparticles from Citrus medica L.

DOI
https://doi.org/10.14719/pst.12375
Submitted
21 October 2025
Published
25-06-2026 — Updated on 12-08-2026
Versions

Abstract

The advanced eco-friendly technology is employed for synthesising nanoparticles (Nps) derived from natural sources. Green synthesis method is used other than chemical and physical approaches due to its reduced time and labour requirements. This study centres on the production of cobalt oxide nanoparticles (CoO Nps) utilising Citrus medica L. plant extract. Cobalt oxide nanoparticles were produced using the extract of C. medica (commonly called as Citron). In this study, the attributes of both C. medica leaf extract and cobalt nitrate hexahydrate (Co(NO3)2.6H2O) were harnessed for green Np synthesis. This approach is expected to drive advancements in diverse disciplines. Characterisation was carried out using ultraviolet-visible (UV) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Cobalt oxide nanoparticles formation was initially confirmed through spectrophotometric evaluation, showing a peak at 280 nm. The usage of FTIR identified the functional groups in both C. medica and CoO Nps. Peaks ranged from 3238 cm-1, indicating hydroxyl, carbonyl and amine groups within the leaf extract, while the peak at 516 cm-1 denoted CoO Nps formation. Field emission scanning electron microscopy (FE-SEM) revealed that the synthesised CoO Nps displayed a spherical structure. X-ray diffraction analysis showed the crystallinity of the synthesised Nps. Antibacterial efficacy was assessed using strains Escherichia coli and Staphylococcus aureus via disc diffusion method and formed inhibition zones of 12 ± 0.07 mm and 13 ± 0.2 mm respectively. Antioxidant potential was evaluated through 2,2-diphenyl-1-picrylhydrazyl assay (DPPH) assay, revealing a maximum scavenging activity of 94.5 %, indicating potent antioxidant capability when compared to the standard.

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