Polyethylenimine (PEI) is one of the most effective polymers for non-viral gene delivery; however, the mechanism by which DNA binds to PEI remains unclear. In this study, the reaction rate between DNA and PEI was determined using quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). The association rate constant was determined as 0.8–1 s–1 mM–1, and the dissociation rate constant was found to be 1–2 ×10–3 s–1. The data obtained from these measurements could be explained using the two-site fitting model. One proposed binding site for the DNA was the PEI; however, the DNA could also have bound directly to the gold surfaces of the sensor devices. Furthermore, the suitability of this two-site model for DNA binding was evaluated in this study. [DOI: 10.1380/ejssnt.2015.99]
