Thermographical Method to Assess the Performance of Magnetic Nanoparticles in Hyperthermia Experiments through Spatiotemporal Temperature Profiles

D. VALDÉS; T.E. TORRES; A.C. MORENO MALDONADO; URRETAVIZCAYA, GUILLERMINA; NADAL, MARCELA S.; M. VASQUEZ MANSILLA; R.D. ZYSLER; G.F. GOYA; E. DE BIASI; E. LIMA JR.

Puerto Varas

Congreso; XII Latin American Workshop on Magnetism and Magnetic Materials (LAW3M2023); 2023

Universidad Central

For magnetic fluid hyperthermia (MFH), dissimilarresults are usually obtained when characterizing magnetic nanoparticles (MNPs) invitro versus dispersed in solvents due to viscosity effects or MNPaggregation [1], thus characterizing MNP systems in media such aspolyacrylamide gels (PAGs) that can reproduce cytosol viscosity [2] is key. Moreover,conventional fiber-optic temperature measurements can monitor only one spot in thesample. A way of following the temperature evolution noninvasively inside cellcultures, tissues or tumors is needed, as well as understanding heat transferin these systems where temperature gradients and heat losses are prevalent [3].We unveil a novel method to generate 2Dtemperature maps for MNP samples in MFH experiments [4]. We tested it byanalyzing two types of 8% PAG with MNPs: one conventionally polymerized(dispersed) and another one polymerized inside a coil with an amplitude of theac field of H = 32 kA/m and a frequency of f = 350 kHz (oriented),where elongated agglomerates were formed. MNP concentrations of both 0.1 and0.5 wt% were used. Power absorption (PA) experiments were performed in thesePAGs (at the same ac field conditions) and the temperature increment evolutionwas monitored through the recording of videos with an IR thermographicalcamera. The processing of the IR camera measurements allowed us to generate spatiotemporal(2D) temperature profiles (see Fig. 1) and the analysis of these profilesallowed us to follow not only the increment of temperature during MFHexperiments but also thermodynamic parameters such as energy, power and heatflux. We also identified spatial inhomogeneities through the temperature maps,which highlights that a 2D analysis could benefit the interpretation of resultsobtained in biological and medical uses. Fig. 1: Temperature increment maps for PA experiments performed in PAGs.The black dotted line indicates the time at which the ac field is switched offand the cooling period of the sample begins. Insets: Photographs of thePAGs. The arrow shows an elongated agglomerate’s density gradient.[1] B. Sanz et al, Sci. Rep. 6, 38733 (2016)[2] T. Yano et al, Biosci.Biotechnol. Biochem. 57, 528 (1993)[3] J. Bosque et al, R. Soc. Open Sci. 8,201234 (2021)[4]D.P. Valdés et al, Phys. Rev. Applied 19, 014042 (2023)