Table 1.

Mass of iron internalized in the samples and in the negative controls (denoted by (C)) and corresponding average number of nanoparticles internalized by each cell, obtained from magnetic measurements.

sample	μ S (10 −6 A m 2 )	m Fe (μg)	m Fe /cell (pg)	NPs/cell (10 5 )
100 μg ml−1 24 h	1.790	20.80	27.8	211.9
100 μg ml−1 24 h (C)	0.101	1.16	1.6	11.8
100 μg ml−1 6 h	1.040	12.08	16.1	123.2
100 μg ml−1 6 h (C)	0.068	0.81	1.1	8.3
10 μg ml−1 24 h	0.026	0.30	0.4	3.1
10 μg ml−1 6 h	0.018	0.21	0.3	2.1