Label-Free Multi-Microfluidic Immunoassays with Liquid Crystals on Polydimethylsiloxane Biosensing Chips

Area of Science:

• Biomedical Engineering
• Materials Science
• Analytical Chemistry

Background:

• Liquid crystals (LCs) exhibit unique optical properties sensitive to surface interactions.
• Microfluidic devices enable miniaturized and controlled biological assays.
• Immunoassays are crucial for detecting specific biomolecules like proteins.

Purpose of the Study:

• To develop a novel liquid crystal-based multi-microfluidic immunoassay.
• To demonstrate label-free detection of proteins using optical signals.
• To assess the sensitivity and robustness of the developed biosensor.

Main Methods:

• Fabrication of a polydimethylsiloxane-based multi-microfluidic device.
• Utilizing the optical properties of liquid crystals influenced by antigen-antibody binding.
• Employing pressure-driven flow for sequential detection.
• Testing the sensor with bovine serum albumin (BSA) and its immunocomplex.

Main Results:

• The LC orientation changed from homeotropic (dark) to a different state (bright) upon antigen binding.
• Sequential detection of analytes was achieved through optical signal changes.
• The biosensor demonstrated a naked-eye detection limit of 0.01 µg/mL for BSA.
• The assay showed robustness and simplicity for immunodetection.

Conclusions:

• A new format for LC-based multi-microfluidic immunoassays was successfully developed.
• The device provides a simple, robust, and label-free platform for immunodetection.
• This technology holds potential for sensitive and rapid diagnostic applications.