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<p>Magnetic nanoparticles (NPs), particularly magnetite (Fe₃O₄), are of increasing interest for biomedical and nanotechnological applications due to their unique magnetic and biocompatible properties. This study presents the gamma radiation-induced biomineralization of Fe₃O₄ NPs in the thermophilic bacterium, <i>Bacillus</i> sp. KA2, isolated from the “Ashagi Istisu” hot spring (Kelbajar, Azerbaijan). The bacterium was exposed to gamma radiation at doses of 500&#xa0;Gy and 2000&#xa0;Gy, with non-irradiated cells serving as controls. Electron Paramagnetic Resonance (EPR) spectroscopy revealed Fe₃O₄-specific signatures (g = 2.32, ∆H = 320 G) exclusively in irradiated samples, indicating radiation-assisted nanoparticle formation. A notable 30% reduction in free radical signals was observed at 500&#xa0;Gy, suggesting oxidative stress modulation. X-ray diffraction (XRD) analysis revealed characteristic peaks corresponding to magnetic nanoparticles. Transmission Electron Microscopy (TEM) analysis confirmed the intracellular and cell wall-associated localization of the Fe<sub>3</sub>O<sub>4</sub> NPs. At 500&#xa0;Gy, the nanoparticles were approximately 10&#xa0;nm in diameter with gray-scale intensity of 5200, accompanied by moderate thickening of the cell wall and partial cytoplasmic reorganization. In contrast, 2000&#xa0;Gy irradiation induced severe ultrastructural alterations, including extensive membrane disruption and cytoplasmic disintegration, while nanoparticles persisted, exhibiting diameters of 10–15&#xa0;nm and gray-scale values ranging from 5200 to 5400. Fourier-transform infrared (FTIR) spectroscopy suggested that functional groups of organic compounds may play a role in the formation and stabilization of the nanoparticles. The results demonstrate that gamma radiation induces dose-dependent biomineralization of Fe₃O₄ in bacterial cells, leading to the reproducible formation of magnetic nanoparticles.</p> Graphical abstract <p></p>

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Bioengineered Magnetite Nanoparticles Via Radiation Stimulated Biomineralization in Thermophilic Microorganisms

  • 期刊论文

  • 发表日期：

    2026年5月18日

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  • Gunay Abbasli,
  • Eldar Gasimov,
  • Fuad Rzayev,
  • Rovshan Khalilov,
  • Aziz Eftekhari,
  • Salman Majeed,
  • Muhammad Zafar,
  • Saleh AlNadhari,
  • Khuzin Dinislam,
  • Adnan Amin

摘要

Magnetic nanoparticles (NPs), particularly magnetite (Fe₃O₄), are of increasing interest for biomedical and nanotechnological applications due to their unique magnetic and biocompatible properties. This study presents the gamma radiation-induced biomineralization of Fe₃O₄ NPs in the thermophilic bacterium, Bacillus sp. KA2, isolated from the “Ashagi Istisu” hot spring (Kelbajar, Azerbaijan). The bacterium was exposed to gamma radiation at doses of 500 Gy and 2000 Gy, with non-irradiated cells serving as controls. Electron Paramagnetic Resonance (EPR) spectroscopy revealed Fe₃O₄-specific signatures (g = 2.32, ∆H = 320 G) exclusively in irradiated samples, indicating radiation-assisted nanoparticle formation. A notable 30% reduction in free radical signals was observed at 500 Gy, suggesting oxidative stress modulation. X-ray diffraction (XRD) analysis revealed characteristic peaks corresponding to magnetic nanoparticles. Transmission Electron Microscopy (TEM) analysis confirmed the intracellular and cell wall-associated localization of the Fe3O4 NPs. At 500 Gy, the nanoparticles were approximately 10 nm in diameter with gray-scale intensity of 5200, accompanied by moderate thickening of the cell wall and partial cytoplasmic reorganization. In contrast, 2000 Gy irradiation induced severe ultrastructural alterations, including extensive membrane disruption and cytoplasmic disintegration, while nanoparticles persisted, exhibiting diameters of 10–15 nm and gray-scale values ranging from 5200 to 5400. Fourier-transform infrared (FTIR) spectroscopy suggested that functional groups of organic compounds may play a role in the formation and stabilization of the nanoparticles. The results demonstrate that gamma radiation induces dose-dependent biomineralization of Fe₃O₄ in bacterial cells, leading to the reproducible formation of magnetic nanoparticles.

Graphical abstract