Table 4.

Summary of cellular responses to Ag ENMs with different surface charge and chemical composition

Surface charge:			Negative		Neutral		Positive
Surface chemical composition:			Citrate	SDS	Disperbyk	Tween	Chitosan	Byk
Intercellular localisation	Cytoplasm	24 h	+	+	+	+	+	+
	Nucleus	24 h	-	-	-	-	+	+
	Mitochondria	24 h	-	-	-	-	+	-
Cytotoxicity	Cells morphology	2 h	-	-	-	-	+ (s)	+
		24 h	+	+	-	-	+ (s)	+
	Trypan blue exclusion	2 h	-	-	-	-	+	++
		24 h	-	-	-	-	++	++
	Relative Growth Activity	24 h	++	++	-	++	+++	+++
Genotoxicity and mutagenicity	Comet assay – Strand breaks	2 h	+				++	++
		24 h	++	+	++	+	(x)	(x)
	Comet assay – Oxidative DNA lesions	2 h	+++	+++	+++	+++	+++	+++
		24 h	+++	++	++	+++	(x)	(x)
	HPRT gene mutation	24 h	++ (s)	+	+	++ (s)	+	++

The relative tendency of each Ag ENMs to induce cellular responses related to uptake, viability, cytotoxicity, genotoxicity and mutagenicity after 2–24 h exposure

(−) no harmful effects were observed in any of tested concentrations

(+) indicates a significant increase in the intracellular event in one from three-five tested concentrations/localisation in selected cells compartments/change in cells morphology

(++) indicates a significant increase in the intracellular event in two-three from three-five tested concentrations

(+++) a significant increase in the intracellular event in one from four-five tested concentrations

(s)- Toxic effect of Ag ENMs stabilizers

(x)- Fully biological effect could not be evaluated due to strong method saturation