Studies on the synthesis of fluorescein-5-isothiocyanate: A fluorescent nanomarker for biosensors

A review of the methods of synthesis of fluorescein is given. An improved method of synthesis of a chromatographically pure fluorescein-5-isothiocyanate nanomarker for labeling immunoglobulins is developed, which will allow creation of high-quality biosensors. A unique method of synthesis of 5-aminofluorescein, a precursor of fluorescein-5-isothiocyanate, was also developed. The properties of fluorescein-5-isothiocyanate were studied to find that it exists in two forms having different solubility.