SYNTHESIS, CHARACTERIZATION, AND MULTIFACETED ANTIBACTERIAL ASSESSMENT OF CIPROFLOXACIN LOADED IRON OXIDE NANOPARTICLES AGAINST STAPHYLOCOCCUS AUREUS AND PSEUDOMONAS AERUGINOSA

Abstract

The rapid emergence of multidrug-resistant (MDR) bacterial pathogens has necessitated the development of novel antimicrobial strategies to improve the therapeutic efficacy of conventional antibiotics. In the present study, ciprofloxacin-loaded iron oxide nanoparticles (Cip-IONPs) were chemically synthesized using a co-precipitation method and comprehensively characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ^1H nuclear magnetic resonance (^1H NMR). The synthesized nanoparticles exhibited predominantly spherical morphology with an average particle size of approximately 10 ± 10 nm, while spectroscopic and structural analyses confirmed the successful loading of ciprofloxacin onto the iron oxide nanoparticle. The antibacterial efficacy of Cip-IONPs was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa using minimum inhibitory concentration (MIC), antibiofilm assay, acridine orange/ethidium bromide (AO/EtBr) fluorescence staining, scanning electron microscopy, and quantitative real-time PCR (qRT-PCR). The Cip-IONPs exhibited potent antibacterial activity with a MIC of 0.9 μg/ml against both bacterial strains and demonstrated concentration-dependent inhibition of biofilm formation, achieving inhibition rates exceeding 88% at 500 μg/ml. Fluorescence microscopy and SEM analyses revealed severe membrane disruption and extensive bacterial cell death following nanoparticle treatment. Furthermore, qRT-PCR analysis demonstrated significant downregulation of the biofilm-associated pslA gene in P. aeruginosa (0.337-fold) and the DNA gyrase gene gyrB in S. aureus (0.137-fold), indicating effective suppression of bacterial virulence and DNA replication. Collectively, these findings demonstrate that Cip-IONPs exhibit enhanced antibacterial activities through synergistic interactions between ciprofloxacin and iron oxide nanoparticles, highlighting their potential as an effective nanotherapeutic platform for combating multidrug-resistant bacterial infections.