Growth of a Novel Nanostructured ZnO Urchin: Control of Cytotoxicity and Dissolution of the ZnO Urchin

Table 1 The release of Zn from the different cell growth substrates into the cell medium

Cell growth substrate type	Total Zn concentration in the cell medium at different sampling times (mg/L, mean ± SD)
Cell growth substrate type	3 days (experiment 1)	7 days (experiment 1)	16 h (experiment 2)
Cell medium (background)	0.08 ± 0.02 (n = 4)	0.09 ± 0.01 (n = 4)	0.09 ± 0.01 (n = 4)
Glass cover slip (negative control)	0.12 ± 0.06 (n = 4)	0.08 ± 0.02 (n = 4)	0.18 ± 0.04 (n = 4)
Si	0.05 ± 0.01 (n = 4)	0.04 ± 0.02 (n = 4)	0.16 ± 0.09 (n = 3)
Si + Au	0.07 ± 0.04 (n = 4)	0.04 ± 0.01 (n = 4)	0.18 ± 0.11 (n = 3)
Si + Au + ZnO urchin2	16.4 ± 2.0 (n = 3)	23.4 ± 2.5 (n = 3)	13.8 ± 3.9 (n = 3)
Si + Au + ZnO urchin2 + PVDF-HFP	NA	NA	6.9 ± 1.5 (n = 2)
Plain Zn disc (positive control)	NA	NA	25.4 ± 5.3 (n = 4)

There were no cells in the negative control to account for the Zn content in the cell medium and in the culture wells
Abbreviations: NA data not available, SD standard deviation, n number of analysed data