INVESTIGATING THE BACTERICIDAL EFFICACY OF MAGNETIC METAL FERRITE NANOPARTICLES SYNTHESIZED BY NON-HYDROLYTIC COPRECIPITATION
New methods of combating bacterial infections must constantly be explored due to the efficiency of the evolution of antibiotic resistance. Nanoparticles can be paired with current antibacterial agents to increase susceptibility. Bare cobalt ferrite and silverdoped ferrite nanoparticles as well as those capped with caprylic acid were synthesized using a previously reported novel non-hydrolytic coprecipitation method. The particles were characterized using FTIR to verify the capping agent and XRD to corroborate that the magnetic spinel ferrite crystal phase was achieved. DLS and TEM provided information about hydrodynamic particle diameter and physical particle morphology, respectively. All particles were tested against broth cultures of Bacillus licheniformis, Erwinia carotovora, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Streptococcus pneumoniae. Infrared spectra of all capped particles verified the presence of caprylic acid in both the precursor and nanoparticle material. Diffractograms showed Miller indices corresponding to known magnetite phases. DLS size-characterization of CoFe2O4 caprylate and bare particles indicated hydrodynamic diameters of approximately 100 nm and 401.6 nm, respectively. Silverdoped ferrite caprylate and bare particles had hydrodynamic diameters of 50.7 nm and 220.6 nm. TEM micrographs of CoFe2O4 caprylate indicated a spherical monodisperse morphology with a diameter of 3.8 ± 0.8 nm. EDS studies indicated only slight silver incorporation in the silver-doped ferrite nanoparticles, while cobalt ferrite particles showed a ratio of 2.4:1 of iron to cobalt. Biological broth testing had varying levels of success with the ethanol control groups often overshadowing possible particle results. Fluorescence testing also had limited success due to light absorption from the particles. Plate counting assays provided the most conclusive results despite not being as delineated as broth culture assays with both silver-doped ferrite caprylate and bare silver-doped ferrite nanoparticles being effective at inhibition of E. coli, P. aeruginosa, S. enterica, S. aureus, S. pneumoniae. Silver-doped ferrite caprylate exhibited a rescue effect for B. licheniformis and E. carotovora with bare silver-doped ferrite exhibiting significant inhibition. Overall, silver-doped ferrite had better inhibitory results than cobalt ferrite, likely due to the presence of silver.