Charge Sensitive Optical Detection for Measurement of Small-Molecule Binding Kinetics

Area of Science:

• Biophysical techniques
• Analytical chemistry
• Molecular interaction analysis

Background:

• Traditional label-free optical detection methods primarily measure molecular mass, limiting sensitivity for small molecules.
• The charge sensitive optical detection (CSOD) technique offers a sensitive alternative for detecting molecular interactions, irrespective of molecular size.

Purpose of the Study:

• To introduce and detail the CSOD technique for label-free, real-time molecular interaction measurement.
• To highlight CSOD's capability in studying small molecules and its compatibility with high-throughput screening.

Main Methods:

• Utilizes an optical fiber functionalized with probe molecules within a microplate well.
• Applies an alternating electrical field to induce fiber oscillation, driven by surface charge.
• Monitors changes in oscillation amplitude and phase via optical imaging of the fiber tip.

Main Results:

• CSOD measures molecular binding by detecting alterations in the fiber's surface charge.
• The technique demonstrates sensitivity to charge changes, independent of the binding molecule's size.
• CSOD is compatible with standard microplate platforms for scalable analysis.

Conclusions:

• CSOD provides a sensitive, label-free method for real-time molecular interaction studies, particularly for small molecules.
• Its compatibility with microplate platforms facilitates high-throughput screening applications in drug discovery.