Effects of Normothermic Conditioned Microwave Irradiation on Cultured Cells Using an Irradiation System with Semiconductor Oscillator and Thermo-regulatory Applicator

Abstract

We investigated the effects of microwave irradiation under normothermic conditions on cultured cells. For this study, we developed an irradiation system constituted with semiconductor microwave oscillator (2.45 GHz) and thermos-regulatory applicator, which could irradiate microwaves at varied output powers to maintain the temperature of cultured cells at 37 °C. Seven out of eight types of cultured cells were killed by microwave irradiation, where four were not affected by thermal treatment at 42.5 °C. Since the dielectric properties such as ε’, ε” and tanδ showed similar values at 2.45 GHz among cell types and media, the degree of microwave energy absorbed by cells might be almost the same among cell types. Thus, the vulnerability of cells to microwave irradiation might be different among cell types. In HL-60 cells, which were the most sensitive to microwave irradiation, the viability decreased as irradiation time and irradiation output increased; accordingly, the decrease in viability was correlated to an increase in total joule. However, when a high or low amount of joules per minute was supplied, the correlation between cellular viability and total joules became relatively weak. It is hypothesized that kinds of cancer cells are efficiently killed by respective specific output of microwave under normothermic cellular conditions.

Physical assessments of termites (Termitidae) under 2.45 GHz microwave irradiation

“…This device did not possess the sensors to monitor the inflow/outflow power of the energy but could monitor the temperature inside the applicator and the petri dish (3.5 cm diameter) with a thermistor. The dish material was Polystyrene, which interacted with the microwaves in nearly the same manner as the air 52 . Thus, the heat generated by the microwave irradiation efficiently occurred in the insect body rather than in the dish.…”

Normothermic Microwave Irradiation Induces Death of HL-60 Cells through Heat-Independent Apoptosis

“…It is important to note that while the main focus of this study is on the death pathways induced by microwave irradiation in HL-60 cells, we also previously observed a microwave irradiation-induced decrease in cell viability in other types of cancer cells, including T98G, MDA-MB-231, and KATO III 21 . Furthermore, after irradiation and a 6-h incubation period, the number of late stage apoptotic cells (both Annexin V and PI positive) was increased in all cell types, while early apoptotic cells (Annexin V positive, PI negative) were not observed (Fig.…”

“…Interestingly, we previously found that cell viability was decreased in seven types of cultured cancer cells when treated with microwave irradiation that maintained the cellular temperature at 37 °C 21 . In human promyelomonocytic leukemia (HL-60) cells, viability decreased as irradiation time and output increased.…”

Synthesis, Characterization and Magnetic Hyperthermia of Monodispersed Cobalt Ferrite Nanoparticles for Cancer Therapeutics

“…When the excited electron alters its spin direction and returns back to its ground state, then it emits phonons. The microwave fields and the magnetic dipoles are coupled to convert the energy of radiation to heat [ 55 ]. When CFNPs present in the saline suspension are exposed to microwave radiation, then the collision between nanoparticles, salt ions and water molecules tend to increase thus leading to higher heat generation.…”

“…Furthermore, when both MDA-MB 231 (triple negative breast cancer cell lines) and MRC-5 (fibroblast normal cell lines) are exposed to the same increasing concentration of the CFNPs, cancer cells are found to have more mortality compared to the normal ones upon exposure to microwaves which can be corroborated from Figure 6 . The reason for this vulnerability is still not known [ 55 ].…”