Fluorescence microscopic observations of catecholamines within the cured films were performed by a modified method. Due to high autofluorescence of the obtained materials, the boronic ester method for confirming catechol presence was not possible. As a result, we developed an alternative method to confirm both the presence of catechol units on the surface of crosslinked films, as well as their functionality and reactivity. We used an amine functionalized far-red dye (ATTO 643-amine, ATTO-TEC GmbH, Siegen Germany) which is hydrophilic, has a high quantum yield, and the primary amine can attack catechols via by Michael addition or forming a Schiff base . Crosslinked strips (approx. 16 mm by 7 mm, 3 per group) were incubated in 1.5 mL of 10 mM TRIS buffer (pH = 9) with 20 µg/mL of ATTO 643-amine (prepared from 4 mg/mL dye stock in DMSO), overnight, at 37 °C. As a control, additional samples were incubated in parallel in the absence of dye. After staining, samples were rinsed three times with PBS and imaged using the Cy5 fluorescence channel (Ex: 620, Em: 700) of Leica DMi8 inverted microscope (Leica HC PL FLUOTAR 10x/0.32 DRY objective and Leica DEC7000 GT 1920x1440 camera). Two or three fields of view were collected per sample. Image analysis was performed using scientific Python ecosystem, including `aicsimageio` , `dask` , `napari` , `matplotlib` , and `numpy` . We quantified the differences between samples by comparing histograms using Wasserstein distance (also known as "earth mover's distance") using the `scipy` Python library