Gold-functionalized magnetic nanoparticles restrict growth of Pseudomonas aeruginosa

Superparamagnetic iron oxide nanoparticles (SPIONs) and their derivatives (aminosilane and gold-coated) have been widely investigated in numerous medical applications, including their potential to act as antibacterial drug carriers that may penetrate into bacteria cells and biofilm mass. Pseudomonas aeruginosa is a frequent cause of infection in hospitalized patients, and significant numbers of currently isolated clinical strains are resistant to standard antibiotic therapy. Here we describe the impact of three types of SPIONs on the growth of P. aeruginosa during long-term bacterial culture. Their size, structure, and physicochemical properties were determined using transmission electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. We observed significant inhibition of P. aeruginosa growth in bacterial cultures continued over 96 hours in the presence of gold-functionalized nanoparticles (Fe₃O₄@Au). At the 48-hour time point, growth of P. aeruginosa, as assessed by the number of colonies grown from treated samples, showed the highest inhibition (decreased by 40%). These data provide strong evidence that Fe₃O₄@Au can dramatically reduce growth of P. aeruginosa and provide a platform for further study of the antibacterial activity of this nanomaterial.