Label-free sensing of binding to microarrays using Brewster angle straddle interferometry.

Area of Science:

• Surface Science
• Biophysics
• Analytical Chemistry

Background:

• Detecting molecular interactions at interfaces is crucial for various scientific fields.
• Existing methods for surface binding detection have limitations in sensitivity or convenience.
• Native silicon oxide layers offer a versatile platform for interface studies.

Purpose of the Study:

• To develop a novel interferometric method for detecting and quantifying chemical binding at interfaces.
• To demonstrate the technique's sensitivity and applicability using a model system of DNA aptamers and thrombin.
• To highlight the method's convenience and insensitivity to experimental parameters.

Main Methods:

• Utilizing destructive interference of light at silicon oxide interfaces (oxide/water and oxide/silicon).
• Employing a thin native oxide layer on silicon as the interference medium.
• Measuring the selective binding of thrombin to immobilized DNA aptamers.

Main Results:

• Achieved near-complete destructive interference by exploiting phase shifts at interfaces.
• Successfully detected and quantified the selective binding of thrombin to DNA aptamers.
• Demonstrated sensitivity for detecting sub-angstrom surface binding, comparable to advanced techniques.
• Obtained results in quantitative agreement with theoretical predictions.

Conclusions:

• The developed interferometric method provides a highly sensitive and convenient approach for surface binding detection.
• The technique leverages native silicon oxide properties for precise molecular interaction analysis.
• This method shows promise for applications in biosensing and surface characterization.