Spin Probes as Scavengers of Free Radicals in Cells

Abstract

Spin probes can be used to monitor biological membranes, including the penetration of different molecules into cells. The aim of the present studies was an investigation of the endocytosis process of two spin labels—2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) and 4-hydroxy-TEMPO (TEMPOL)—into yeast cells and a leukemia cell line (HL-60, ATCC CCL-240) by Electron Spin Resonance (ESR). The ESR method is helpful for the direct detection of free radicals. The cell incubation and endocytosis of spin probes were carried out at 310 K. In contrast, the ESR measurements of yeast cells and a leukemia cell line with spin probes were at 240 K. Spectral differentiation was observed; hence, the spin probes present in suspension and attached to the cell membrane could be distinguished. The ESR signal changes of spin probes depended on spin probe concentration, cell number, and type of cell (healthy/cancerous). Additionally, the effect of external factors (oxygen and vitamin C) on the ESR signal decay of spin markers in the cell solution was established. The experimental results prove that the spin probes (TEMPO and TEMPOL) could scavenge free radicals inside the cell. At the same time, the mechanism of spin probe interaction in suspension was determined based on the measurements at low temperatures.

The Effect of a Magnetic Field on the Transport of Functionalized Magnetite Nanoparticles into Yeast Cells

“…Figure 4c,d demonstrate the spectra of nanoparticles and TEMPOL attached to them, recorded at 295 K. The ESR signal from the TEMPOL spin label recorded at low temperature (Figure 4b) was taken to observe the interactions between nanoparticles and cells and the uptake of nanoparticles. According to our previous results, such a spectrum consisting of three lines obtained in the frozen sample indicated the penetration of nanoparticles into cells [16,17,32].…”

“…If the resonance condition is met and an appropriate quantum of radiation with energy corresponding to the energy difference between these levels is supplied to the system, the ESR phenomenon will be registered as the first derivative of the absorption signal [19][20][21]. It has been successfully applied in various studies, including those investigating the properties of magnetic nanoparticles [22][23][24][25][26][27], iron complexes and free radicals in blood and tissues [28][29][30][31][32][33][34][35], as well as geological and archaeological materials [36][37][38][39]. ESR studies confirm the penetration of nanoparticles into cells and facilitate monitoring of this whole process.…”

“…ESR studies confirm the penetration of nanoparticles into cells and facilitate monitoring of this whole process. Additionally, magnetic nanoparticles with attached spin labels (TEMPO or TEM-POL), as potential antioxidant agents, have been investigated for their possible use in treating inflammatory diseases, as radioprotectors in radiotherapy, and scavengers of free radicals in cells [17,32,40,41].…”

“…Yeast cells were also applied under various cellular stress impacts, including oxidative, osmotic, and ethanol accumulation [59]. In turn, Krzyminiewski and Dobosz applied yeast cells in the study of magnetic nanoparticle uptake and the antioxidant properties of a TEMPO spin probe using ESR [16,17,32].…”

Preliminary Study on the Effect of a Single High-Energy Electromagnetic Pulse on Morphology and Free Radical Generation in Human Mesenchymal Stem Cells

“…The only known direct method that enables the measurement of free radicals is electron paramagnetic resonance (EPR) [ 20 ]. This method has been successfully applied in previous studies on free radicals in biological materials, such as blood samples [ 21 , 22 , 23 ], and in the studies of radical processes occurring in both healthy and cancer cells [ 24 , 25 , 26 ].…”