FeCo nanoparticles as antibacterial agents with improved response in magnetic field: An insight into the associated toxicity mechanism.

The emergence of multi-drug resistant bacterial infections has resulted in increased interest in the development of alternative systems which can sensitize bacteria to overcome resistance. In an attempt to contribute to the existing literature of potential antibacterial agents, we present here, a first report of the antibacterial potential of FeCo nanoparticles, both as stand-alone devices and in presence of magnetic field, against the bacterial strains of S. aureus and E. coli. A relatively simple polyol process was employed for nanoparticle synthesis. Formation of FeCo alloy in the desired BCC phase was confirmed by X-Ray Diffraction with a high saturation magnetization (Ms~180 Am2kg-1). Uniformly sized spherical structures with sharp edges were obtained. Solution stability was confirmed by the zeta potential value of -27.8 mV. Dose dependent bacterial growth inhibition was observed, the corresponding linear correlation coefficients being, R2 = 0.74 for S. aureus and R2 = 0.76 for E. coli. Minimum inhibitory concentration was accordingly ascertained to be >1024 μg/ml for both. Bacterial growth curves have been examined upon concomitant application of external magnetic field of varying intensities and revealed considerable enhancement in the antibacterial response upto 63% in a field of 100 mT. An effort has been made to understand the bacterial inhibitory mechanism by relating with the chemical and physical properties of the nanoparticles. The ease of field assisted targeting and retrieval of these highly magnetic, antibacterial nano-devices, with considerably improved response with magnetic fields, make them promising for several medical and environment remediation technologies.