8-Aminopyrene-1,3,6-trisulfonic Acid (sodium salt) is an anionic fluorescent dye used as a reporter for glucose sensing and detecting other saccharides, with excitation/emission spectra of 425/503 nm. It can be utilized in solution or immobilized via attachment of an aldehyde-functionalized monomer by reductive amination without significantly altering fluorescence intensity.

APTS labeling of N-glycans
Procedure:
1. Use sodium cyanoborohydride (NaBH3CN) as a reducing agent. Dissolve a mixture of N-glycans (∼100 μg) and isomaltose (25 pmol) in a 0.2 mL-PCR thin-wall tube.
2. Dissolve 5 μL of 50 mM APTS in 500 mM citric acid.
3. Add 5 μL of 1.0 M NaBH3 to the sample mixture and incubate the mixture at 55°C for 50 min. Quench the reaction with 140 μL of cold distilled water (total volume, 150 μL) and purify.
4. Purify the APTS-labeled N-glycans by passing through IPAE and HILIC-SPE spin columns.