Fig. 7
ESAT-6 detection with 75 nM anti-ESAT-6 antibody. a Representation for color changes. Different concentrations of ESAT-6 was mixed with 75 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 0.85 nM was detected with the clear color change (red to blue). Photographs were taken by a digital camera. b Spectral changes at the wavelength from 400 to 800 nm. Peaks were indicated with the respective colored spheres. Specificity assay was carried out using CFP-10 and shown to be a negative control