Evaluation of hydrodynamic size and zeta-potential of surface-modified an nanoparticle-DNA conjugates via Ferguson analysis

We evaluate Ferguson analysis as a method for simultaneously measuring the size and zeta-potential of gold nanoparticle-DNA (An NP-DNA) conjugates. This approach is highly suitable when the particle size is <20 nm and biomolecular conformation results in a nonspherical or nonlinear conjugate, causing conventional dynamic light scattering and zeta-potential measurements to be unable to achieve consistent results. We show the applicability of the method by varying the size of gold nanoparticles (5-20 nm) and the loading of methoxypolyethylene glycol/DNA on particle surface and buffer concentrations. Due to the low ionic mobility of tris-borate-EDTA buffer (TBE) and relatively high zeta-potential of An NP-DNA, Henry's solutions with higher order correction terms are necessary for obtaining the zeta-potential from the measured free mobility and size.