LAUSR

Abstract Metal-substituted cobalt ferrites [M x Co (1− x ) Fe 2 O 4 (M = Zn, Cu, Mn; x  = 0.0, 0.25, 0.5, and 0.75)] were synthesized via a sol–gel technique. The ferrite structures were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, surface analysis using the Brunauer–Emmett–Teller method, and energy-dispersive X-ray spectroscopy. Antimicrobial activity of these ferrites against selected pathogenic microbes was determined. The structures remained cubic spinel phases after substitution of metals. Substitution strongly influenced the microstructure and homogeneous grain distribution. The particle size of the ferrites increased linearly with increase in their annealing temperature. The surface area of zinc cobalt ferrite nanoparticles (ZCFO) was 52.56 m 2 /g, the average pore size was 1.84 nm, and pore volume was 0.136 mL/g. All ferrites showed antimicrobial activity toward all pathogens selected. Of these, the most powerful was ZCFO, showing zones of inhibition of 13.0 mm against Bacillus subtilis and Staphylococcus aureus and 12.0 mm against Candida albicans . Gamma-irradiated ZCFO nanoparticles (150.0 kGy) maintained higher antimicrobial activity than non-irradiated particles, e.g. being active toward S. aureus (16.0 mm). ZCFO is proposed as a candidate material for industrial and biomedical purposes.