Table 2. Characterization of Four Engineered Nanomaterial (ENM) Dispersions (at 50 μg/mL) in RPMI with 10% FBS Cell Culture Medium Obtained from Dynamic Light Scattering^a and Tunable Resistive Pulse Sensing.

dynamic light scattering (DLS)					tunable resistive pulse sensing (TRPS)
ENM type	dh,z-ave (nm)	PdI	ζ (mV)	peak size	size mean (nm)	size mode (nm)	range (nm)	concentrationb (#/mL)	fraction of total number
SWCNH-ox	261 ± 3	0.23	–9.3 ± 1.0	small	249	212	177–572	2.70 × 1010	0.844
				large	660	684	572–877	5.00 × 1009	0.156
Printex- 90	270 ± 8	0.37	–13.1 ± 1.1	small	264	198	173–717	9.80 × 1007	0.971
				large	1068	860	717–1476	2.90 × 1006	0.029
CeO2	265 ± 2	0.31	–12.1 ± 0.2	small	268	211	183–659	1.80 × 1008	0.987
				large	1066	847	659–1922	2.60 × 1006	0.013
Ni Inco	234 ± 7	0.40	–14.4 ± 1.5	small	268	199	176–715	8.80 × 1007	0.990
				large	1136	904	715–1897	4.10 × 1006	0.010

^ad_h,z-ave, hydrodynamic diameter; PdI, polydispersity index, a measure of the broadness of size distribution; ζ, Zeta Potential, a measure of surface charge in the cell culture medium.

^bConcentration for SWCNH-ox determined at 5 μg/mL.