Magnetic nano-apatites for drug delivery and tissue engineering

Bioactive hydroxyapatite nano-phases endowed with intrinsic superparamagnetism, designed to act as new stimuli-responsive drug delivery systems or to enhance cell homing and colonization of bone and osteochondral scaffolds thus enhancing tissue regeneration.
The recent development of new intrinsically superparamagnetic hydroxyapatite nanoparticles (Fe-HA) was achieved through controlled substitution of Ca2+ ions with Fe2+/3+ ions, with specific Fe/Ca and Fe2+/Fe3+ ratios. Due to the bioactivity, bioresorbability and safety of this new biomaterial, as well as its ability to be activated by external signal, new generation bio-devices endowed with intrinsic superparamagnetic properties has been obtained.
The super-paramagnetism of Fe-HA is accompanied by effective hyperthermia properties that can be exploited towards new generation anti-cancer therapies.
Besides, Fe-HA nanoparticles and/or Fe-HA/biopolymer (like alginate, gelatin, chitosan, PNIPAM) composite microbeads developed by double emulsion processes can be linked to relevant bioactive molecules through thermo-labile ligands and released upon remotely induced hyperthermia, thus functioning as new smart, stimuli-responsive drug delivery systems. The presence of the polymeric phase allow to deeply control the release kinetic through specific chemical cross-linking processes, performed by varying the kind and the percentage of cross linking agents.
Moreover, Fe-HA based particles can be functionalized and internalized by cells that can be moved, upon external signal, in targeted therapeutic sites or to provide enhanced in vivo tissue engineering thus aiding the regeneration of extended bone/osteochondral parts. The controlled release allows to perform local pharmaceutical therapies, avoiding systemic therapies and their related undesired toxicity effects.
The new devices based on Fe-HA are subject of an international patent (WO2012014172).