Potential-Assisted DNA Immobilization as a Prerequisite for Fast and Controlled Formation of DNA Monolayers.

Highly reproducible and fast potential-assisted immobilization of single-stranded (ss)DNA on gold surfaces is achieved by applying a pulse-type potential modulation. The desired DNA coverage can be obtained in a highly reproducible way within minutes. Understanding the underlying processes occurring during potential-assisted ssDNA immobilization is crucial. We propose a model that considers the role of ions surrounding the DNA strands, the distance dependence of the applied potentials within the electrolyte solution, and most importantly the shift of the potential of zero charge during the immobilization due to the surface modification with DNA. The control of the surface coverage of ssDNA as well as the achieved speed and high reproducibility are seen as prerequisites for improved DNA-based bioassays.