Real-time dynamics of single-DNA molecules undergoing adsorption and desorption at liquid-solid interfaces

Area of Science:

• Biophysics
• Surface Science
• Analytical Chemistry

Background:

• Understanding DNA behavior at interfaces is crucial for developing advanced separation techniques and biosensors.
• The conformational dynamics and adsorption/desorption of DNA influence its detection and manipulation.

Purpose of the Study:

• To investigate the conformational dynamics and adsorption/desorption behavior of individual lambda-DNA molecules at different liquid-solid interfaces.
• To elucidate the role of surface properties (pH, buffer composition, surface chemistry) and solution conditions (organic solvent) in DNA-surface interactions.

Main Methods:

• Total internal reflection fluorescence microscopy (TIRFM) was employed to image individual lambda-DNA molecules at liquid-solid interfaces.
• Adsorption durations and molecular dynamics were analyzed under varying pH, buffer compositions, and in the presence of organic solvents on fused-silica and C18 surfaces.

Main Results:

• On fused-silica surfaces, DNA conformation and adsorption were sensitive to pH and buffer composition.
• Adsorption duration histograms showed asymmetry similar to elution peaks in capillary chromatography and electrophoresis, correlating surface accessibility with adsorption factors.
• On C18 surfaces, DNA dynamics were significantly altered by organic solvents and pH, with hydrophobic interactions being the primary adsorption driver.

Conclusions:

• Surface chemistry and solution conditions critically control DNA adsorption and dynamics at liquid-solid interfaces.
• The findings provide insights into DNA behavior relevant to chromatographic separations and surface-based assays.
• Hydrophobic interactions play a dominant role in DNA adsorption on non-polar surfaces like C18.