Fig. 5

ESAT-6 detection at higher concentrations. a Graphical representation for the detection of ESAT-6. Different concentrations of ESAT-6 was mixed with 60 nM of antibody, and after 30 min of incubation, GNP was added. Then 800 mM of NaCl was added to induce the color change. ESAT-6 from 0.5 nM was detected with the clear color change (red to blue). Photographs were taken by the digital camera as in figure inset. b Spectral changes at the wavelength from 400 to 800 nm. Peaks were indicated with the respective colored spheres