Zone of inhibition (ZOI) diameter of (a) ZnO, (b) 2NZO, and (c) 5NZO samples against E. coli at different concentrations. N.D. indicates that the zone of inhibition was not detecteda.
Samples | Zone of inhibition (mm) | |||
---|---|---|---|---|
(i) 0.5 mg mL−1 | (ii) 1.25 mg mL−1 | (iii) 2.5 mg mL−1 | (iv) 5 mg mL−1 | |
(a) ZnO | N.D. | N.D. | N.D. | N.D. |
(b) 2NZO | N.D. | N.D. | N.D. | 15 |
(c) 5NZO | N.D. | N.D. | 15 | 20 |
DMSO (v) was used as negative control in all Petri dishes.