Table 3.

The concentration of extract (CE₅₀) obtained from Cur_Cu_4%, Cur_Cu_6%, and Cur_Cu_8% biomaterials, which is required to inhibit fibroblast viability (BJ cells) to 50%. The CE₅₀ values were calculated via 4-parameter nonlinear regression analyses, GraphPad Prism 5, version 5.04). The values of selective index were calculated based on results obtained for bacteria and fibroblasts. The higher value of Selective Index (SI) is, the extract from biomaterial is safer for eukaryotic cells.

Biomaterial Used to Obtain Extract in Eagle’s Minimum Essential Medium (EMEM)	Concentration of Extract Required to Inhibit Fibroblast Viability to 50% (CE50) [%]	Selective Index (SI) * $\mathbf{SI}= \frac{{\mathbf{CE}}_{50} \mathbf{for} \mathbf{fibroblast} \mathbf{cells}}{{\mathbf{CE}}_{50} \mathbf{for} \mathbf{bacterial} \mathbf{cells}}$
		E. coli	S. aureus
Cur_Cu_4%	30.91 ± 1.23	0.40	ND **
Cur_Cu_6%	29.49 ± 1.43	0.44	ND **
Cur_Cu_8%	26.48 ± 1.73	0.56	0.40

* The values of CE₅₀ for bacterial cells were adopted from Table 2. ** ND—not determined. It was not possible to obtain SI value due to lack of value of CE₅₀ for bacterial cells.