Magneto-responsive chain-like arrangements of size-tuned and cobalt-doped ferrites derived from silica-encapsulated precursors

Anisotropic materials, such as intracellular nanochains in magnetotactic bacteria, exhibit significant potential in biomedicine and technology due to their magnetic, direction-dependent properties. However, their synthesis is limited due to scalability and purification issues. Here, we present an alternative route to bioinspired magneto-responsive nanostructures, specifically chain-like arrangements composed of truncated cubic cobalt-doped ferrite particles. The magnetic nanoparticles are synthesized in an eco-friendly manner via coprecipitation and hydrothermal conversion of silica-coated nanorods with varying shell thicknesses. A distinct relationship emerged between the cobalt-to-iron ratio, nanoparticle dimensions, and mass magnetization, revealing that these parameters increase with silica shell thickness and reaction temperature. When an external magnetic field is applied, the randomly distributed particles align themselves into nanochains, facilitating the determination of the number of particles in both parallel and perpendicular orientations, as calculated from Small-Angle X-ray Scattering analysis. It is observed that the cluster numbers vary in comparison to the dipole-dipole interaction energy and particle size due to the formation of these chain-like structures and bundles. A critical evaluation of the characteristics of both individual particles and chains summarizes their suitability for biomedical applications.