Nanomedicine and Pharmaceutical Nanotechnology

In this study, biologically synthesized iron oxide nanoparticles, called magnetosomes, are made fully biocompatible by removing potentially toxic organic bacterial residues such as endotoxins at magnetosome mineral core surface and by coating such surface with poly-L-lysine, leading to magnetosomes-poly-L-lysine (M-PLL). M-PLL antitumor efficacy is compared with that of chemically synthesized iron oxide nanoparticles (IONPs) currently used for magnetic hyperthermia. M-PLL and IONPs are tested for the treatment of glioblastoma, a dreadful cancer, in which intratumor nanoparticle administration is relevant, using a mouse allograft model of murine glioma (GL-261 cell line). A magnetic hyperthermia treatment protocol is proposed, in which 25µg in iron of iron oxide nanoparticles per mm³ of tumor are administered and exposed to 11 to 15 magnetic sessions during which an alternating magnetic field of 198kHz and 11 to 31mT was applied for 30 minutes to attempt reaching temperatures of 43-46°C. M-PLL are characterized by a larger specific absorption rate (SAR of 40W/gFe compared with 26W/gFe for IONPs as measured during the first magnetic session), a lower strength of the applied magnetic field required for reaching a target temperature of 43-46°C (11 to 27mT compared with 22 to 31mT for IONPs), a lower number of mice re-administered (four compared to six for IONPs) and a longer residence time within tumors (four days compared to one day for IONPs). Despite of a less homogenous that dispersion M-PLL are less homogenously dispersed in the tumor compared to IONPs, M-PLL lead to higher antitumor efficacy with full tumor disappearances achieved in 50% of mice compared with 20% for IONPs.