Photo-induced damages of cytoplasmic and mitochondrial membranes by a [C60]fullerene malonic acid derivative.

The biological activities of fullerene derivatives have attracted much attention in the last decade. In this paper, effects of dimalonic acid C(60) (DMA C(60)) on cytoplasmic membrane, intracellular calcium concentration ([Ca(2+)](i)), and mitochondrial membrane in HeLa cells were studied by using laser scanning confocal microscopy together with fluorescent probes propidium iodide (PI), fluo-3 acetoxymethyl ester (fluo-3 AM), and tetramethyl rhodamine methyl ester (TMRM). The data showed that under laser irradiation produced by a Kr/Ar laser source with a low power less than 1 mW, DMA C(60) might induce damages against both cytoplasmic and mitochondrial membranes in a time- and dose-dependent manner. Prior to leakage of cytoplasmic membrane, a transient increase in [Ca(2 +)](i) occurred due to influx of calcium from the culture medium. These data provided some novel clues to explain the mechanisms involved in the photo-induced cytotoxicity of fullerene derivatives.