# Layer by layer preparation of Fe3O4@Cg-DTC/AgNPs as colloidal antimicrobial and anti-biofilm agent

## TL;DR

Researchers created a nanocomposite material that effectively fights bacteria and biofilms without harming cells.

## Contribution

A novel Fe3O4@Cg-DTC/AgNPs nanocomposite was developed with strong antibacterial and anti-biofilm properties.

## Key findings

- The nanocomposite showed stronger antibacterial effects than ciprofloxacin against tested bacteria.
- It inhibited biofilm formation at very low concentrations for Escherichia coli.
- The material was non-toxic to NIH-3T3 cells in cytotoxicity assays.

## Abstract

To solve antimicrobial resistance in bacteria, metal nanoparticles (NPs) have gained tremendous attention due to their effectiveness and ease of use. Here, we prepared a core–shell dithiocarbonate carbon functionalized magnetic composite and employed it to support and stabilize the silver nanoparticle (Ag NPs). A chemical reduction method was employed to decorate the Ag NPs over the surface of the magnetic composite. The prepared materials were characterized using FT-IR, XRD, VSM, EDX, SEM, TEM, particle size distribution analysis, and elemental mapping. The results demonstrated that the designed support effectively prevented aggregation of the Ag NPs, ensuring their uniform dispersion throughout the structure. The Ag NPs decorated core–shell material was used as an antimicrobial agent against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The minimum inhibitory concentrations of nanocomposite against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were 0.58 ± 0.38, 1 ± 0, and 4.67 ± 3.06 µg mL−1, respectively. The results demonstrated that Fe3O4@Cg-DTC/AgNPs nanocomposite has a stronger antibacterial effect than the control antibiotic, ciprofloxacin. Regarding biofilm inhibition, the lowest concentration of Fe3O4@Cg-DTC/Ag composite required to inhibit biofilm formation in E. coli was 0.0625 µg mL−1, while the concentrations required for P. aeruginosa and S. aureus were 0.5 and 1 µg mL−1, respectively. Cytotoxicity assays confirmed that the nanocomposite did not induce toxicity in NIH-3T3 cells. Overall, these results demonstrate the potent antibacterial and anti-biofilm activity of the Fe3O4@Cg-DTC/AgNPs nanocomposite while maintaining cytocompatibility.

The online version contains supplementary material available at 10.1038/s41598-025-29960-w.