Magnetic bioinspired hybrid nanostructured collagen-hydroxyapatite scaffolds supporting cell proliferation and tuning regenerative process

A bioinspired mineralization process was applied to develop biomimetic hybrid scaffolds made of (Fe²⁺/Fe³⁺)-doped hydroxyapatite nanocrystals nucleated on self-assembling collagen fibers and endowed with super-paramagnetic properties, minimizing the formation of potentially cytotoxic magnetic phases such as magnetite or other iron oxide phases. Magnetic composites were prepared at different temperatures, and the effect of this parameter on the reaction yield in terms of mineralization degree, morphology, degradation, and magnetization was investigated. The influence of scaffold properties on cells was evaluated by seeding human osteoblast-like cells on magnetic and nonmagnetic materials, and differences in terms of viability, adhesion, and proliferation were studied. The synthesis temperature affects mainly the chemical-physical features of the mineral phase of the composites influencing the degradation, the microstructure, and the magnetization values of the entire scaffold and its biological performance. In vitro investigations indicated the biocompatibility of the materials and that the magnetization of the super-paramagnetic scaffolds, induced applying an external static magnetic field, improved cell proliferation in comparison to the nonmagnetic scaffold.