Understanding the Dependence of Nanoparticles Magnetothermal Properties on Their Size for Hyperthermia Applications: A Case Study for La-Sr Manganites

Abstract

Magnetic oxides are promising materials for alternative health diagnoses and treatments. The aim of this work is to understand the dependence of the heating power with the nanoparticle (NP) mean size, for the manganite composition La0.75Sr0.25MnO3 (LSMO)—the one with maximum critical temperature for the whole La/Sr ratio of the series. We have prepared four different samples, each one annealed at different temperatures, in order to produce different mean NP sizes, ranging from 26 nm up to 106 nm. Magnetization measurements revealed a FC-ZFC irreversibility and from the coercive field as function of temperature we determined the blocking temperature. A phase diagram was delivered as a function of the NP mean size and, based on this, the heating mechanism understood. Small NPs (26 nm) is heated up within the paramagnetic range of temperature (T>Tc), and therefore provide low heating efficiency; while bigger NPs are heated up, from room temperature, within the magnetically blocked range of temperature (T<TB), and also provide a small heating efficiency. The main finding of this article is related with the heating process for NPs within the magnetically unblocked range of temperature (Tc>T>TB), for intermediate mean diameter size of 37 nm, with maximum efficiency of heat transfer.

CaCO3 Nanoparticles Coated with Alternating Layers of Poly-L-Arginine Hydrochloride and Fe3O4 Nanoparticles as Navigable Drug Carriers and Hyperthermia Agents

“…The theoretical estimation of the SAR parameter has shown that this value increases with the incorporation of nanoparticles into the polymer shell (sample 0c1s). The capsules 0c1s are capable of heating by 10–15 °C based on the experimental results, which are presented in previous studies. − A slow heating rate to a temperature of 42 °C using an external alternating magnetic field is relevant for hyperthermia. The release of a drug from capsules with MNPs embedded in the shell can be achieved by hyperthermia.…”

Green Synthesis of Silver Nanoparticles Using Natural Extracts with Proven Antioxidant Activity

“…Currently, nanoparticles belong to highly advanced and specialized biomedical products [ 1 ]. There are several interesting applications of nanoparticles in medicine and pharmacy: for example, in medical imaging, as nanocomposites, filters, components of drug delivery systems, and formulations for the treatment of cancer [ 2 , 3 , 4 , 5 ]. Gold nanoparticles have found applications in analytical procedures for the detection of cancer cells, proteins, and antibodies.…”

Magnetic Properties and SAR for Gadolinium-Doped Iron Oxide Nanoparticles Prepared by Hydrothermal Method

“…For relaxation loss to be the major loss mechanism and hysteresis loss to be ignored, the particles should exhibit superparamagnetic behavior. In such a state, the ambient temperature T should be above the blocking temperature TB of the particles [70]. It is worth noting that the values of coercivity for all samples are relatively low, as shown in Table 2.…”

“…Another study on 35 nm manganese ferrite nanoparticles of concentration 3 mg/mL at a field intensity of 350 G and a frequency of 765.95 kHz showed that the particles gave an SAR value of 70 W/g [74], while Muhammad Nauman et al studied gadolinium silicide nanoparticles and calculated an SAR value of 3.7 W/g for 43 nm particles at a field of 171 Oe and a frequency of 327 kHz [75]. Finally, a recent study using nanoparticles of different diameters based on La-Sr manganites, and with a low Curie temperature, gave SAR values ranging from 5.6 to 30 W/g [70].…”