Adaptive interferometry of protein on a BioCD

Area of Science:

• Biophysics
• Optical Engineering
• Surface Science

Background:

• Traditional surface profiling methods struggle with dynamic biological samples.
• Subnanometer resolution is crucial for understanding thin biolayer interactions.
• Adaptive optics can correct for optical aberrations and sample movement.

Purpose of the Study:

• To develop and validate an adaptive spinning-disk interferometry system for high-resolution biolayer surface profiling.
• To demonstrate the system's capability for sensitive and specific biosensing of immobilized antibodies.
• To compare transmission and reflection detection modes for immunoassay performance.

Main Methods:

• Utilized a spinning disk with immobilized antibodies for dynamic surface profiling.
• Employed a photorefractive quantum-well device as an adaptive mixer for phase-locking.
• Implemented high-speed phase modulation detection via dynamic two-wave mixing.
• Performed biosensing in both transmission and reflection modes.

Main Results:

• Achieved subnanometer longitudinal resolution in surface profile measurements of biolayers.
• Demonstrated single- and dual-analyte immunoassays with high specificity and no cross-reactivity.
• Reflection-mode detection significantly enhanced sensitivity (1/20th protein monolayer) and provided topographic mapping.
• Successfully differentiated monolayers of different species based on effective optical thickness.

Conclusions:

• Adaptive spinning-disk interferometry is a powerful tool for label-free biosensing with high resolution and sensitivity.
• The adaptive mixer effectively compensates for disk wobble and vibration, ensuring stable measurements.
• Reflection-mode detection offers superior sensitivity and detailed surface characterization for immunoassay applications.