The new EPR molecular oxygen probe fusinite is not toxic to cells

The possible cytotoxic effects of fusinite, a new charcoal-like electron paramagnetic resonance (EPR) oxygen probe, were evaluated in three cell types with very different characteristics and growth features: K562 (an erythroleukemic cell line which grows in suspension), A431 (an epidermal carcinoma cell line which grows in monolayer) and primary cultures of murine fibroblasts (which also grow in adhesion culture) utilizing morphological and functional studies as well as growth analyses. Scanning and transmission electron microscopy as well as fluorescence microscopy were used for the morphological analyses while conductometric relaxation studies in the radiowave frequency range, membrane resistance measurements and adenine nucleotide levels were utilized for the more subtle functional evaluation of cell parameters. The results show that the presence of fusinite particles, even after long internalization times, does not induce any cytotoxic effects in the cells studied. Thus, from these results, it can be deduced that fusinite is non-toxic as well as highly stable, inert and very sensitive to oxygen, and can be used with great success for cell studies where determination of oxygen concentration is important.