Table 1
Inhibitory effect of AgNP and AgGO against Gram-positive and Gram-negative bacteria
Bacteria	Sample concentrations (μg/ml)											Control
	AgNP					AgGO					GO
	100	50	25	12.5	6.25	100	50	25	12.5	6.25	100	-
Gram-positive
S. aureus	×	×	×	×	×	×	×	×	×	×	×	×
S. epidermidis	√	√	×	×	×	×	×	×	×	×	×	×
Gram-negative
E. coli	√	√	√	√	√	√	√	√	√*	√*	×	×
S. typhi	√	√	√	√	×	√	√	√	√	√	×	×

A check indicates positive inhibition effect with no colony growth observed. A check with an asterisk indicates positive inhibition effect with less than five colonies observed. An ex indicates negative inhibition effect.

Chook et al. Nanoscale Research Letters 2012 7:541   doi:10.1186/1556-276X-7-541