An integrated optical Mach–Zehnder interferometer functionalized by β-cyclodextrin to monitor binding reactions

We demonstrate an integrated optical Mach–Zehnder interferometer for the monitoring of guest–host reactions on immobilized β-cyclodextrin (β-CD). Adamantanecarboxylic acid, 4-tert-butylbenzoic acid and methyl orange were investigated as guest molecules. The binding constants of the three guests into the two-dimensionally arranged immobilized cyclodextrins could be determined and are a quarter to a third smaller than the values measured in the three-dimensional environment of a solution.