Anti-bacterial activity of silibinin-functionalized silica-coated Fe3O4 magnetic nanocomposites on Pseudomonas aeruginosa.

The nanocomposites were synthesized and characterized using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The physicochemical analyses confirmed the structural integrity, uniform particle size (34-58 nm), thermal stability (> 600 °C), and magnetic properties of the nanocomposites. The nanocomposites exhibited strong synergistic effects with ciprofloxacin, reducing the minimum inhibitory concentration (MIC) in combination by 4- to 16-fold compared to ciprofloxacin alone. Furthermore, the nanocomposites in combination with ciprofloxacin significantly inhibited biofilm formation in clinical isolates. The gene expression analysis revealed downregulation of key efflux pump genes (mexX, mexY, and oprM), resulting to increased intracellular accumulation of ciprofloxacin. This mechanism potentiated the bactericidal effects of ciprofloxacin, even against resistant strains. These findings highlight the potential of Fe₃O₄@SPN@Silibinin as a biodegradable, stable, and water-soluble nanocarrier for silibinin delivery, offering a novel therapeutic strategy for combat multidrug-resistant bacterial infections. This study presents a promising approach to addressing the growing threat of antibiotic resistance through targeted drug delivery and genetic modulation.