Method for the gram-scale preparation of ferrite nanoparticles for magnetic hyperthermia applications

A method for preparing ferrite nanoparticles having a Specific Absorption Rate (SAR) of at least 100 W/gFe at a frequency of 100 kHz and a magnetic field of 24 kA/m, the method comprising the following steps:

• i) providing a solution comprising a fatty acid, an aliphatic amine, and an alcoholic solvent;
• ii) adding to the solution a directing agent and at least one organometallic precursor compound comprising Fe and optionally a second organometallic precursor compound comprising a metal selected from Mn, Co, Zn, thereby obtaining a reaction mixture;
• iii) transferring the reaction mixture to a sealed reactor, thereby obtaining a filling percentage thereof of between 20 and 70 vol. %;
• and
• iv) heating said sealed reactor to a temperature ranging between 180° C. and 240° C. for a duration of between 3 and 8 hours,
• wherein the directing agent is an aldehyde or ketone of Formula (I):
• R1—(C═O)R2 Formula (I)
• wherein R1 is a linear or branched, saturated or unsaturated carbon chain having a length of from 1 to 13 carbon atoms, optionally substituted with an aromatic substituent, and
• R2 is selected from the group consisting of hydrogen, an aromatic ring and a linear or branched, saturated or unsaturated carbon chain having a length of from 1 to 10 carbon atoms,
• with the provisos that:
• when R2 is hydrogen and R1 is an unsaturated carbon chain substituted with an aromatic substituent, the aromatic substituent is located at position 3 or higher with respect to the carbonyl group —(C═O), or
• when R2 is hydrogen and R1 is a saturated carbon chain substituted with an aromatic substituent, the aromatic substituent is located at position 2 or higher with respect to the carbonyl group —(C═O), with the further proviso that when the aromatic substituent is located at position 2, the aromatic substituent is the sole substituent at position 2.