Iron nanoparticle
Sub-micrometer iron particles
From Wikipedia, the free encyclopedia
Nanoscale iron particles are sub-micrometer particles of iron metal.[1] Due to their high catalytic activity, permanent magnetic properties, low toxicity, and strong adsorption capacity, iron-based nanoparticles are widely utilized in drug delivery, production of magnetic tapes (e.g., camcorders and backup tapes of computers[2]), gene therapy, and environmental remediation.[3]
Synthesis
Iron nanoparticles can be synthesized using two primary approaches: top-down and bottom-up methods.[4]
Top-down Methods
Top-down approaches create nanoparticles by breaking down larger bulk materials into smaller particles, including laser ablation and mechanical grinding.[3]
Bottom-up Methods
Bottom-up approaches involve the chemical and biological synthesis of iron nanoparticles from metal precursors (e.g., Fe(II) and Fe(III)).[3] This method is widely regarded as the most effective and commonly used strategy for nanoparticle preparation.[4] For example, iron nanoparticles can be chemically prepared by reducing Fe(II) or Fe(III) salts with sodium borohydride in an aqueous medium. This process can be described by the following equations:[5][6]
- 4 Fe3+ + 3 BH4− + 9 H2O → 4 Fe0↓ + 12 H+ + 6 H2 + 3 H2BO− (1)
- 4 Fe2+ + 3 BH4− + 9 H2O → 4 Fe0↓ + 8 H+ + 8 H2 + 3 H2BO− (2)
Properties
Application in biomedicine
Iron oxide nanoparticles (IONPs) have widely investigated for applications in biomedicine, including magnetic resonance imaging and cancer therapy via magnetic hyperthermia[8][9]
In addition to these applications, IONPs exhibit strong antibacterial activity and have been explored for drug and viral vector delivery to target cells.[10] Known microorganisms susceptible to the toxic effects of IONPs include Gram-negative bacteria (e.g., Escherichia coli and Klebsiella sp.) and Gram-positive bacteria (e.g., Bacillus sp. and Corynebacterium sp.).[10]
The antibacterial activity of IONPs is primarily attributed to the generation of reactive oxygen species (ROS), a mechanism similar to the Fenton reaction.[10] Specifically, Fe2+ ions react with hydrogen peroxide (H2O2), producing Fe3+ ions and hydroxyl radicals.[11] These highly reactive species induce oxidative damage to bacterial DNA, ultimately leading to cell death.