Figure 2.

Optimization of aptamer concentration; (A) UV-vis spectra of different concentrations of OTA aptamers (400–50 nM) with a fixed volume of AuNPs; (B) A_630/520 absorbance ratio indicating an increase in the aggregation with a decrease in the concentration of aptamer (175 nM) in the presence of 40 mM of NaCl; (C) TEM image of OTA aptamer coated AuNPs, a very thin layer of OTA aptamers was observed around AuNPs; (D,E) Hydrodynamic diameter and Zeta potential of different concentration of OTA aptamers (400–50 nM) conjugated AuNPs; (F) Photographic image of the vials with different concentrations of OTA aptamers.