DNA interaction probed by evanescent wave cavity ring-down absorption spectroscopy via functionalized gold...

Area of Science:

• Biophysical Chemistry
• Spectroscopy
• Nanotechnology

Background:

• Studying DNA strand interactions is crucial for understanding biological processes and disease mechanisms.
• Gold nanoparticles (Au NPs) offer unique optical properties for sensitive detection.
• Evanescent wave cavity ring-down absorption spectroscopy (EW-CRDS) provides high sensitivity for molecular detection.

Purpose of the Study:

• To employ EW-CRDS with Au NPs for studying DNA strand interaction and binding kinetics.
• To determine the adsorption equilibrium constant and binding efficiency of DNA hybridization.
• To apply this method for label-free detection of DNA mutations, specifically for sickle-cell anemia.

Main Methods:

• Utilizing Au NPs functionalized with target DNA, which hybridize with complementary DNA immobilized on a silica surface.
• Measuring the absorbance of Au NPs to quantify DNA interaction and binding.
• Applying Langmuir isotherm fitting to calculate the adsorption equilibrium constant.
• Investigating the influence of ion concentration, pH, and temperature on binding efficiency.

Main Results:

• An adsorption equilibrium constant of 2.2×10(10) M⁻¹ was determined for DNA hybridization using Langmuir fit.
• Binding efficiency was found to be sensitive to ion concentration, buffer pH, and temperature.
• The method successfully detected a gene mutation for sickle-cell anemia with a detection limit of 1.2 pM.
• Distinct differences in adsorption equilibrium constants were observed between mutated and perfectly matched DNA sequences.

Conclusions:

• EW-CRDS coupled with Au NPs is a sensitive technique for studying DNA interaction kinetics.
• This approach enables label-free detection of DNA mutations with high specificity.
• The method holds significant potential for investigating various biological reaction kinetics and diagnostics.