Electrostatic detection of unlabelled single- and double-stranded DNA using capacitive field-effect devices functionalized with a positively charged polyelectrolyte layer

Capacitive field-effect electrolyte-insulator-semiconductor sensors consisting of an Al-p-Si-SiO₂ structure have been used for the electrical detection of unlabelled single- and double-stranded DNA (dsDNA) molecules by their intrinsic charge. A simple functionalization protocol based on the layer-by-layer (LbL) technique was used to prepare a weak polyelectrolyte/probe-DNA bilayer, followed by the hybridization with complementary target DNA molecules. Due to the flat orientation of the LbL-adsorbed DNA molecules, a high sensor signal has been achieved. In addition, direct label-free detection of in-solution hybridized dsDNA molecules has been studied.