The morphological appearance of PLGA-Fluorescein (in this case AV01 is pictured) is a solid crystalline material with a yellow color. When viewed under fluorescent conditions this polymer can be vissualized with an absorbance ~488nm in wavelength and emmision ~520nm similar to other FITC stained structures. Either used alone or mixed with other polymers (suggested minimum of 1:10 ratio PLGA-Fluorescein to non-fluorescent polymers to ensure visibility) this material makes the polymer structure uniquely visible to fluorescent systems such as microscopes so as to easily track the polymer. As the polymer degrades eventually the fluorescein is released from the endcap by chain scission. Initially the loose fluorescein has a brighter fluorescence than the bound fluorescein, but after time the fluorescein elutes into the surrounding solution and the structure loses its fluorescence. This can be used as a tool to track polymer degradation over time.