Table 3.

Interference of oxide nanoparticles on bacterial quantification

Nanoparticles (mg/ml)	ZnO				TiO 2				SiO 2
	S. enterica Newport (cells/ml) a				S. enterica Newport (cells/ml)				S. enterica Newport (cells/ml)
	FMC		CFU	OD 660 b	FMC		CFU	OD 660	FMC		CFU	OD 660
	Total	Live			Total	Live			Total	Live
0	1.37 × 109	1.36 × 109	8.17 × 108	1.37 × 109	1.23 × 109	1.22 × 109	1.18 × 109	1.23 × 109	1.28 × 109	1.26 × 109	6.32 × 108	1.28 × 109
0.1	1.31 × 109	1.30 × 109	1.00 × 109	1.46 × 109	1.00 × 109	9.94 × 108	7.00 × 108	9.16 × 108	1.23 × 109	1.22 × 109	6.50 × 108	1.20 × 109
0.2	1.29 × 109	1.28 × 109	5.83 × 108	1.28 × 109	8.15 × 108	8.05 × 108	5.67 × 108	5.89 × 108	1.22 × 109	1.20 × 109	5.83 × 108	1.18 × 109
0.3	1.27 × 109	1.14 × 109	7.00 × 108	1.19 × 109	7.14 × 108	7.06 × 108	5.50 × 108	3.23 × 108	1.20 × 109	1.18 × 109	5.83 × 108	1.16 × 109
0.5	1.23 × 109	1.21 × 109	6.33 × 108	1.01 × 109	4.26 × 108	4.13 × 108	4.33 × 108	-c	1.24 × 109	1.21 × 109	5.67 × 108	1.15 × 109
1	1.12 × 109	1.10 × 109	5.00 × 108	7.15 × 108	2.41 × 108	2.35 × 108	1.50 × 108	-	1.22 × 109	1.20 × 109	7.17 × 108	1.09 × 109
	S. epidermidis ATCC 12228 (cells/ml)				S. epidermidis ATCC 12228 (cells/ml)				S. epidermidis ATCC 12228 (cells/ml)
0	3.53 × 108	3.46 × 108	9.33 × 107	3.53 × 108	4.46 × 108	4.40 × 108	1.20 × 108	4.46 × 108	5.20 × 108	4.74 × 108	2.00 × 108	5.20 × 108
0.1	2.13 × 108	1.94 × 108	2.18 × 107	2.73 × 108	1.21 × 108	1.19 × 108	2.00 × 107	-	1.06 × 108	9.57 × 107	1.18 × 108	4.48 × 108
0.2	1.37 × 108	1.18 × 108	1.63 × 107	1.23 × 108	2.65 × 107	2.62 × 107	2.00 × 107	-	7.27 × 107	6.55 × 107	6.50 × 107	4.54 × 108
0.3	1.71 × 107	1.45 × 107	1.37 × 107	3.20 × 108	1.46 × 107	1.44 × 107	3.33 × 107	-	5.13 × 107	4.60 × 107	5.00 × 107	5.00 × 108
0.5	1.65 × 107	1.45 × 107	1.33 × 107	1.85 × 108	6.47 × 106	6.40 × 106	5.83 × 107	-	6.72 × 107	6.32 × 107	5.83 × 107	4.75 × 108
1	3.31 × 107	3.00 × 107	1.10 × 107	-	6.20 × 107	6.11 × 107	1.07 × 108	-	2.21 × 108	2.04 × 108	1.18 × 108	4.84 × 108
	E. faecalis ATCC 27274 (cells/ml)				E. faecalis ATCC 27274 (cells/ml)				E. faecalis ATCC 27274 (cells/ml)
0	2.29 × 109	2.28 × 109	1.17 × 109	2.29 × 109	2.21 × 109	2.17 × 109	1.07 × 109	2.21 × 109	2.47 × 109	2.42 × 109	1.87 × 109	2.47 × 109
0.1	2.14 × 109	2.06 × 109	1.50 × 109	2.13 × 109	1.84 × 109	1.81 × 109	9.50 × 108	1.69 × 109	2.17 × 109	2.11 × 109	1.22 × 109	2.40 × 109
0.2	2.0 × 109	1.92 × 109	1.42 × 109	1.73 × 109	1.42 × 109	1.40 × 109	5.50 × 108	1.07 × 109	1.64 × 109	1.61 × 109	1.18 × 109	2.30 × 109
0.3	1.47 × 109	1.44 × 109	1.28 × 109	1.54 × 109	1.23 × 109	1.22 × 109	3.80 × 108	5.26 × 108	1.34 × 109	1.33 × 109	1.14 × 109	2.23 × 109
0.5	1.45 × 109	1.40 × 109	1.15 × 109	8.57 × 108	5.58 × 108	5.54 × 108	1.30 × 108	-	8.69 × 108	8.59 × 108	7.00 × 108	2.10 × 109
1	1.07 × 109	1.03 × 109	7.00 × 108	-	1.70 × 106	1.60 × 106	2.95 × 106	-	4.44 × 108	4.33 × 108	5.00 × 108	1.90 × 109
	E. coli ATCC 25922 (cells/ml)				E. coli ATCC 25922 (cells/ml)				E. coli ATCC 25922 (cells/ml)
0	6.56 × 108	5.64 × 108	3.98 × 108	6.65 × 108	6.41 × 108	6.32 × 108	6.83 × 108	6.41 × 108	5.52 × 108	5.46 × 108	5.67 × 108	5.52 × 108
0.1	5.22 × 108	4.95 × 108	3.93 × 108	6.18 × 108	3.28 × 108	3.26 × 108	8.33 × 107	4.86 × 108	3.73 × 108	3.68 × 108	2.83 × 108	5.21 × 108
0.2	4.50 × 108	4.17 × 108	3.88 × 108	5.56 × 108	7.67 × 107	7.61 × 107	1.17 × 107	3.07 × 108	2.52 × 108	2.49 × 108	2.17 × 108	5.08 × 108
0.3	3.65 × 108	3.54 × 108	3.87 × 108	4.97 × 108	1.90 × 107	1.88 × 107	1.17 × 107	1.63 × 108	2.19 × 108	2.16 × 108	1.50 × 108	5.11 × 108
0.5	1.36 × 108	1.17 × 108	2.93 × 108	2.89 × 108	7.13 × 106	6.97 × 106	9.02 × 106	-	2.03 × 108	2.02 × 108	2.50 × 108	4.76 × 108
1	1.43 × 108	1.37 × 108	3.10 × 108	1.59 × 108	2.21 × 107	2.18 × 107	4.58 × 107	-	2.38 × 108	2.37 × 108	2.83 × 108	4.67 × 108

^aBacterial cell concentrations were measured by flow cytometry (FCM), culture-based counting for colony-forming units (CFU), and spectrophotometer method of optical density (OD) measurement after 1 hr exposure to different concentrations of ZnO, TiO₂ and SiO₂ nanoparticles; inoculum used for each experiment was indicated in the control samples, i.e. no nanoparticles.

^bPresented data were converted from each sample cell concentration according to the each species standard curve of cell/ml vs OD₆₆₀ and as mean of triplicate with standard deviations (SD) of < 5% from FCM and OD⁶⁰⁰ and <10% from CFU. Inoculum used for each experiment was indicated in the control samples, i.e. no nanoparticles.

^cValue was negative.