DNA modulates solvent isotope effects in a nanopore

Researchers have long studied how solvents influence molecular reactions, particularly through isotope effects. In bulk solutions, solvent isotope effects typically reflect hydrogen/deuterium differences in reaction rates. However, the behavior of these effects in confined spaces remains unclear. Prior work has established that α-haemolysin nanopores can detect DNA molecules based on ionic current changes. Yet, the impact of DNA entry on solvent isotope effects has not been fully explored. This gap motivated the current investigation into how DNA interacts with solvent isotope effects within nanopores. No prior work had resolved how DNA presence alters isotope effects in such environments. The question of whether DNA modulates these effects in a measurable way has remained open. This study aims to address that uncertainty by focusing on the modulation of isotope effects in a nanopore setting. The findings could provide new insights into DNA-solvent interactions at the nanoscale.

The goal of this research was to determine how DNA molecules affect solvent isotope effects when passing through α-haemolysin nanopores. The study aimed to measure how the presence of DNA alters the isotope effect ratio between H2O and D2O. The motivation stemmed from the need to understand DNA-solvent interactions in confined geometries. The researchers sought to quantify the isotope effect modulation in nanopores compared to bulk solution. They focused on the ratio kH/kD to assess the impact of DNA on solvent dynamics. The study aimed to test whether DNA entry enhances or suppresses isotope effects. The researchers also wanted to determine if pore blockage levels correlate with isotope effect changes. This work addresses a specific gap in nanopore-based isotope effect analysis.

The study used α-haemolysin nanopores immobilized in lipid bilayers to detect DNA entry. Ionic current measurements were taken in both H2O and D2O solutions. The isotope effect was calculated as the ratio kH/kD from current blockade data. The experiment focused on single DNA molecules entering the nanopore. The researchers monitored changes in current as DNA translocated through the pore. They compared isotope effects in bulk solution to those observed in the nanopore. The study used statistical analysis to determine the significance of observed isotope effects. The results were compared across different levels of pore blockage to assess modulation.

The strongest finding was that isotope effects increased in nanopores compared to bulk solution. In H2O, the kH/kD ratio reached approximately 1.6 in nanopores. In bulk solution, the same ratio was around 1.2. The isotope effect enhancement was observed when DNA partially blocked the pore. However, when the pore was most blocked, the isotope effect dropped to kH/kD ≤ 1.1. These results suggest that DNA entry modulates solvent isotope effects in a nanopore. The modulation was strongest at intermediate levels of pore blockage. The study found no evidence of isotope effects exceeding 1.6 in any condition. The results indicate that DNA alters solvent dynamics within the nanopore environment.

The authors conclude that DNA molecules modulate solvent isotope effects in α-haemolysin nanopores. The isotope effect ratio kH/kD increased from bulk levels when DNA partially blocked the pore. The study found that the highest isotope effects occurred at intermediate blockage levels. The results suggest that DNA alters the local solvent environment within the nanopore. The authors propose that DNA entry affects hydrogen/deuterium exchange rates in the pore. They suggest that the modulation is strongest when DNA partially occupies the pore. The findings do not indicate that DNA enhances isotope effects beyond 1.6 in any condition. The study supports the idea that DNA-solvent interactions are detectable through isotope effects in nanopores.