Partitioning Indicator Displacement Assay

Area of Science:

• Analytical Chemistry
• Supramolecular Chemistry
• Chemical Sensing

Background:

• Indicator displacement assays rely on molecular recognition by receptor molecules.
• A novel transduction mechanism is needed for label-free analyte detection.

Purpose of the Study:

• To introduce a new sensing mechanism: the partitioning indicator displacement assay (PIDA).
• To demonstrate selective small molecule detection using PIDA.

Main Methods:

• Developed a two-phase sensor with a receptor phase (CTAB, octanol, Blue 1) and an aqueous phase.
• Utilized optical monitoring of indicator displacement for label-free detection.
• Employed coarse-grained molecular dynamics simulations to understand the mechanism.

Main Results:

• The PIDA sensor selectively detected Red 40 over similarly charged analytes.
• Sensorgram analysis indicated a self-organized liquid crystalline layer.
• Molecular dynamics simulations revealed supramolecular aggregation driving assay selectivity.

Conclusions:

• PIDA offers a novel, label-free approach for detecting small molecules.
• The assay's selectivity is linked to analyte partitioning in a fluid organic phase.
• This method has potential for detecting various small molecules and understanding phase-separated biological systems.