Novel synthesis of superparamagnetic magnetite nanoclusters for biomedical applications

In this work, we report a novel method of single step facile synthesis of magnetite nanoclusters via thermal decomposition of iron(III) acetylacetonate in a liquid mixture of tri(ethylene glycol) (TREG) and triethanolamine (TREA). The optimized ratio of TREG : TREA has been found to be 1 : 4 (v/v) for the formation of well dispersed MNC-14 magnetite nanoclusters with high M-s values (75 emu g(-1)) as compared to MNC-10 magnetite nanoparticles (63 emu g(-1)). The MNC-14 nanoclusters were found to be nontoxic to MCF-7 cells up to an iron concentration of 10 mg ml(-1). The MNC-14 nanoclusters yielded high specific absorption rate (SAR) values (similar to 500 Watt g(-1) at 89 kA m(-1) AC magnetic field and 240 kHz frequency) and thus qualified for their possible use in magnetic hyperthermia treatment, while MNC-10 nanoparticles possess a much lower SAR value of 135 Watt g(-1). In vitro magnetic hyperthermia experiments (using the MNC-14 nanoclusters with the iron concentration of 0.5 mg ml(-1)) showed about 74% loss in viability of MCF-7 breast cancer cells indicating that they are a very suitable candidate for magnetic hyperthermia treatment of cancer. The r2 and r2(*) relaxivity values of MNC-14 nanoclusters (294.99 and 450.05 s(-1) mM(-1)) as measured by a 9.4 T MRI scanner were higher than those for the MNC-10 nanoparticles (205.6 and 309.2 s(-1) mM(-1)). The MNC-14 nanoclusters also showed very promising in vivo tumor imaging. Thus, the newly synthesized novel MNC-14 nanoclusters possess great potential in clinical MRI and magnetic hyperthermia applications and may be used simultaneously for cancer diagnosis and therapy.