Purpose: This study aimed to determine the efficacy of thermotherapy in the presence of gold nanoparticles (GNPs) and microwave (MW) radiation at a frequency of 2450 MHz on the survival of Leishmania major promastigotes and amastigotes. Materials and methods: L. major promastigotes (strain MRHO/IR/75/ER) were cultured in RPMI-1640 medium supplemented with foetal bovine serum and antibiotic. The promastigotes were incubated with GNPs for 2 h. After washing, thermotherapy was performed by MW irradiation. After 48 h the promastigote survival rate was assessed using Alamar Blue assay. In the second part of the study, after culture and proliferation of J744 cells, the infected macrophages were incubated with the GNPs and were inserted under MW irradiation. After 24 h, the number of amastigotes in the macrophages was determined after Giemsa staining by a light microscope. Result: Increased exposure time of the microwave to the parasites in the presence of GNPs induced a significant decline in promastigotes survival rate in comparison to similar samples without GNPs. The least survival of amastigotes was also recorded in the groups containing GNPs. The presence of GNPs during MW irradiation was more lethal for promastigotes and amastigotes in comparison to MW alone. Conclusion: Thermotherapy using MW radiation in the presence of GNPs may be proposed as a new approach to treat leishmaniasis in future studies.

Superparamagnetic cobalt ferrite nanoparticles (CoFe ₂ O ₄ ) possess favourite advantages for theranostic applications. Most of previous studies reported that CoFe ₂ O ₄ magnetic nanoparticles (MNPs) are suitable candidates for induction of hyperthermia and transfection agents for drug delivery. The present study synthesized and investigated the potential use of CoFe ₂ O ₄ as a contrast agent in magnetic resonance imaging (MRI) by using a conventional MRI system. The CoFe ₂ O ₄ were synthesized using co‐precipitation method and characterized by TEM, XRD, FTIR, EDX and VSM techniques. Relaxivities r ₁ and r ₂ of CoFe ₂ O ₄ were then calculated using a 1.5 Tesla clinical magnetic field. The cytotoxicity of CoFe ₂ O ₄ was evaluated by the MTT assay. Finally, the optimal concentrations of MNPs for MRI uses were calculated through the analysis of T ₂ weighted imaging cell phantoms. The superparamagnetic CoFe2O4 NPs with an average stable size of 10.45 nm were synthesized. Relaxivity r ₁ , ₂ calculations resulted in suitable r ₂ and r ₂ / r ₁ with values of 58.6 and 51 that confirmed the size dependency on relaxivity values. The optimal concentration of MNPs for MR image acquisition was calculated as 0.154 mM. Conclusion: CoFe ₂ O ₄ synthesized in this study could be considered as a suitable T ₂ weighted contrast agent because of its high r ₂ / r ₁ value.