CY5.5-COOH (Cyanine 5.5 carboxylic acid) is a fluorescent dye commonly used in biological imaging, cell imaging, protein localization, and immunostaining.

Fluorescent labeling of PP microplastics
This experiment uses the CSD method to fluorescently label PP microplastics for biodistribution analysis.
1. Solution preparation: Use DMSO to prepare CY5.5-COOH into a certain mother solution concentration and dilute it to 50 mg/mL for standby use.
Note: The mother solution is stored at -80℃ or -20℃, and the working solution is prepared and used immediately.
2. Operation steps:
1. Add 15g PP microplastics to 150 mL distilled water and 150 mL THF and stir for 10 minutes.
2. Add the diluted working solution CY5.5-COOH (50 mg/mL) to the PP microplastic suspension and stir for 4 days.
3. After the reaction is completed, use qualitative filter paper (2 to 3 µm) to vacuum filter and separate the Cy-PP microplastics to remove unlabeled CY5.5-COOH in the reaction suspension.
4. Wash with distilled water and ethanol.
5. Dry the Cy-PP microplastics in a dark place at 40°C.
6. Analyze the morphology and chemical structure of Cy5.5 labeled PP using SEM and FT-IR spectroscopy, respectively. [1]