Figure 1. Overall strategy for quantifying DNA bound to AuNPs
using UV-visible spectroscopy. (1) The concentration of DNANPs
is determined from their absorbance at 520 nm. (2) DNANPs
are decomposed using KCN, and (3) the concentration of
DNA is determined from the absorbance of the resultant solution
at 260 nm, as shown in the equation.
The solution of DNA-NPs (Figure 2a) exhibited a UVvisible
absorbance peak characteristic of AuNPs at 520 nm
and an absorbance peak characteristic of DNA at 260 nm. The
latter absorbance was absent from the UV-visible spectrum of
DNA-free AuNPs of the same core size, which was normalized
to have the same A520 .