Toward a Quantitative Relationship between Nanoscale Spatial Organization and Hybridization Kinetics of Surface Immobilized Hairpin DNA Probes.

Hybridization of DNA probes immobilized on a solid support is a key process for DNA biosensors and microarrays. Although the surface environment is known to influence the kinetics of DNA hybridization, so far it has not been possible to quantitatively predict how hybridization kinetics is influenced by the complex interactions of the surface environment. Using spatial statistical analysis of probes and hybridized target molecules on a few electrochemical DNA (E-DNA) sensors, functioning through hybridization-induced conformational change of redox-tagged hairpin probes, we developed a phenomenological model that describes how the hybridization rates for single probe molecules are determined by the local environment. The predicted single-molecule rate constants, upon incorporation into numerical simulation, reproduced the overall kinetics of E-DNA sensor surfaces at different probe densities and different degrees of probe clustering. Our study showed that the nanoscale spatial organization is a major factor behind the counterintuitive trends in hybridization kinetics. It also highlights the importance of models that can account for heterogeneity in surface hybridization. The molecular level understanding of hybridization at surfaces and accurate prediction of hybridization kinetics may lead to new opportunities in development of more sensitive and reproducible DNA biosensors and microarrays.