Characterization of iron oxide nanoparticles adsorbed with cisplatin for biomedical applications.

The aim of this study was to characterize the behaviour of cisplatin adsorbed magnetic nanoparticles (cis-MNPs) for minimal invasive cancer treatments in preliminary in vitro investigations. Cisplatin was adsorbed to magnetic nanoparticles (MNPs) by simple incubation. For stability determinations, cis-MNPs were incubated in dH(2)O, phosphate-buffered saline (PBS) and fetal calf serum (FCS) at 4-121 degrees C up to 20 weeks. Hydrodynamic diameters were measured using laser diffraction. The extent of cisplatin linkage was determined by atomic absorption spectrometry. The magnetite core size was assessed by vibrating sample magnetometry and transmission electron microscopy. The specific loss power (SLP) was measured in an alternating magnetic field. Our results showed that a maximum of 10.3 +/- 1.6 (dH(2)O), 10 +/- 1.6 (PBS) and 13.4 +/- 2.2 (FCS) mg cisplatin g(-1) Fe could be adsorbed to MNPs. With hyperthermal (42 degrees C) or thermal ablative (60 degrees C) temperatures, used for therapeutic approaches, cisplatin did not desorb from cis-MNPs in dH(2)O during incubation times of 180 or 30 min, respectively. In PBS and FCS, cisplatin amounts adsorbed to MNPs decreased rapidly to approximately 50% and 25% at these temperatures. This cisplatin release will be necessary for successful chemotherapeutic activity and should increase the therapeutic effect of magnetic heating treatment in medicinal applications. The hydrodynamic diameters of MNPs or cis-MNPs were around 70 nm and magnetization data showed superparamagnetic behaviour. The obtained mean core diameter was around 12 nm. The SLP of the sample was calculated to be 75.5 +/- 1.6 W g(-1). In conclusion, cis-MNPs exhibit advantageous features for a facilitated desorption of cisplatin in biological media and the heating potential is adequate for hyperthermic treatments. Therefore, even though further detailed investigations are still necessary, tentative use in local tumour therapies aiming at a specific chemotherapeutic release in combination with magnetic heating seems to be feasible in the long term.