Ferrocene-Derived Carbon Nanotubes Inhibit E. coli in Laboratory Assays

Multi-walled carbon nanotubes synthesized by chemical vapor deposition using ferrocene showed concentration-dependent antibacterial activity against Escherichia coli ATCC 25922 in laboratory assays. In the reported study, the minimum inhibitory concentration (MIC) was 256 micrograms per milliliter, while viable-count testing supported a minimum bactericidal concentration (MBC) of 256 micrograms per milliliter under the experimental conditions.

The work, published in Scientific Reports on 21 October 2026, evaluated the as-grown nanotube preparation against a single laboratory strain of E. coli. Researchers used agar well diffusion, broth microdilution and viable-count plating to assess inhibition. The as-grown material was characterized by X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. These analyses supported the formation of graphitized multi-walled nanotube structures and detected iron-containing residues associated with the ferrocene precursor, which served as both the carbon source and iron catalyst during chemical vapor deposition.

The agar well-diffusion assay produced clear concentration-related differences in antibacterial activity. Inhibition-zone diameters measured 26 millimeters at 512 micrograms per milliliter, 21 millimeters at 256, 19 millimeters at 128, 9 millimeters at 64 and 7 millimeters at 32 micrograms per milliliter. No inhibition zone was observed for the negative control. Across the tested range of 1–512 micrograms per milliliter, the study reported a concentration-dependent reduction in bacterial growth, with the strongest measured inhibition at the upper end of that range.

Broth microdilution identified 256 micrograms per milliliter as the MIC, based on the absence of visible bacterial growth, and blank-corrected quantitative measurements provided supplementary confirmation of this endpoint. When cultures were subsequently plated on drug-free Mueller–Hinton agar, no recoverable colonies were found after exposure at 256 or 512 micrograms per milliliter. On the basis of that viable-count result, the researchers reported an MBC of 256 micrograms per milliliter for the conditions tested.

The results characterize the antibacterial performance of the complete preparation as tested, rather than isolating the contribution of the nanotube structure itself. The material was evaluated without post-synthesis purification, so the observed inhibition may also have involved contributions from iron-containing residues or other synthesis-derived components. The findings therefore demonstrate concentration-dependent antibacterial activity of as-grown ferrocene-derived multi-walled carbon nanotubes against E. coli ATCC 25922 in laboratory media; they do not by themselves establish the mechanism of action or performance outside the tested conditions.

Subject of Research: Laboratory antibacterial assessment of ferrocene-derived multi-walled carbon nanotubes against Escherichia coli ATCC 25922

Article Title: Antibacterial activity of ferrocene-derived multi-walled carbon nanotubes synthesized by chemical vapor deposition against Escherichia coli

Article References: Ahmed, S. K., Taay, Y. M., Ahmed, A. J., Khudhayer, H. H., Hussein, S. M. F., & Abbas, Z. S. (2026). Antibacterial activity of ferrocene-derived multi-walled carbon nanotubes synthesized by chemical vapor deposition against Escherichia coli. Scientific Reports. https://doi.org/10.1038/s41598-026-70564-9

Image Credits: AI Generated

DOI: 10.1038/s41598-026-70564-9

Keywords: E. coli, multi-walled carbon nanotubes, ferrocene, chemical vapor deposition, antibacterial activity, minimum inhibitory concentration, minimum bactericidal concentration, Raman spectroscopy, X-ray diffraction, laboratory assay, Antibacterial, activity