Lanthanum manganese perovskite nanoparticles as possible in vivo mediators for magnetic hyperthermia

Manganese perovskite La0.75Sr0.25MnO3 nanoparticles of the crystallite size 20-180nm were prepared starting from citrate gel precursor by annealing in the range of 570-900 degrees C. It is shown that the decrease of the crystallite size leads to a gradual decrease of the magnetization and Curie temperature. The observed behaviour is a consequence of a non-collinear spin arrangement at the surface layer of crystallites, estimated to be of similar to 5 nm. Magnetic heating experiments were carried out with an aqueous stable suspension of a selected sample (M-IT = 42 emu/g, T-c = 352 K) under an alternating field of H-max = 88 mT, v = 108 kHz. The yielded values of specific absorption rate (SAR) were found to be larger than 500 W/g(Mn) at 27 degrees C and 350W/g(Mn), at 37 degrees C. (c) 2005 Elsevier B.V. All rights reserved.