Table 1. Physicochemical properties of ZnO NP.

Measurements	20 nm			100 nm
Modification	Pristine	Citrate	L-serine	Pristine	Citrate		L-serine
Primary size (nm)a	26.8 ± 4.5	26.9 ± 4.3	27.1 ± 7.5	95.1 ± 12.9		100.2 ± 22.9	95.3 ± 23
Hydrodynamic size (nm)b	399 ± 16	341 ± 61	219 ± 3	354 ± 11		299 ± 9	384 ± 6
Zeta potential (mV)	21.4 ± 4.6	-36.0 ± 2.6	30.0 ± 3.4	15.8 ± 1.7		-25.3 ± 57.6	25.4 ± 2.5

^aThe primary size was measured by SEM.

^bThe hydrodynamic size and zeta potential was measured in DW.