A Comparison\nof DNA–DNA Hybridization Kinetics\nin Complex Media on Planar and Nanostructured Electrodes

A comprehensive investigation into how nanostructures\nalter real-time\nDNA hybridization kinetics in both buffer and complex media and under\na wide range of probe and target concentrations is currently lacking.\nIn response, we use a real-time, wash-free, and <i>in situ</i> assay to study DNA hybridization kinetics by performing continuous\nelectrochemical measurements in different media. We investigated the\ndifferences in hybridization kinetics under three regimes of probe\ndensity (low, medium, and high) and over three orders of magnitude\nof target concentrations (0.01–1 μM). Additionally, we\ncompared the performance of planar and nanostructured electrodes in\nbuffer, blood, urine, and saliva. Our experiments indicate that adding\nnanostructures to the transducer surface is only effective under a\nspecific probe/target concentration regime. Additionally, we found\nthat direct electrochemical readout is possible in the examined physiological\nmedia, with measurements in blood showing the highest and saliva showing\nthe lowest signal magnitudes compared to buffer.