title: An electrostatic model for DNA surface hybridization.
abstract: DNA hybridization at surfaces is a crucial process for biomolecular detection, genotyping, and gene expression analysis. However, hybridization density and kinetics can be strongly inhibited by electric fields from the negatively charged DNA as the reaction proceeds. Here, we develop an electrostatic model to optimize hybridization density and kinetics as a function of DNA surface density, salt concentrations, and applied voltages. The electrostatic repulsion from a DNA surface layer is calculated numerically and incorporated into a modified Langmuir scheme, allowing kinetic suppression of hybridization. At the low DNA probe densities typically used in assays (<10(13)/cm(2)), electrostatics effects are largely screened and hybridization is completed with fast kinetics. However, higher hybridization densities can be achieved at intermediate DNA surface densities, albeit with slower kinetics. The application of positive voltages circumvents issues resulting from the very high DNA probe density, allowing highly enhanced hybridization densities and accelerated kinetics, and validating recent experimental measurements.
authors.affiliation: Geballe Laboratory for Advanced Materials, Department of Materials Science and Engineering, Stanford University, Stanford, California, USA.
authors.forename: Ian Y
authors.initials: IY
authors.lastname: Wong
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Melosh
mesh_terms: D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D015203:Reproducibility of Results; D012492:Salts / Q000737:chemistry; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D012492:Salts; D004247:DNA