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A stable dispersion of micron size magnetite spheres in a ferrofluid exhibits several interesting magnetically induced effects like zero forward scattering, enhanced backward scattering etc. Here we show that at a critical magnetic field the dispersion inhibits propagation of certain optical frequencies. The field required to induce this photonic band gap is quite moderate and the technique can be easily adopted for lab-on-chip devices.

Nanomagnetic functional oxides were synthesized through an auto combustion method. The purity and magnetism of nano oxides samples were confirmed by energy dispersive X-ray spectroscopy and magnetometry measurements. Nano manganese ferrite (MnFe 2 O 4 ) (M3), magnesium ferrite (MgFe 2 O 4 ) (M5), and magnesium manganese-mixed ferrite (Mg 0.5 Mn 0.5 Fe 2 O 4 ) (M1) possess particle size of 35 nm, 13 nm, and 5 nm respectively. Bacteriostatic performance of synthesized nanomagnetic oxides and streptomycin sulfate (SS) coated samples was checked for antibacterial activity. As-prepared and coated magnetic oxides were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The drug coating on nanomagnetic ferrites exhibited significant effects on various bacteria. The effect of uncoated and coated specimens on Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus was confirmed by disc diffusion assay on Mueller Hinton agar plates. Furthermore, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) showed that streptomycin-conjugated nanoparticles were more effective compared to bare nanoparticles. The development of coated nanomagnetic drugs can be useful in guided drug delivery system. However, to prove this, in vivo studies are required.