Fluorene Derivative Disodium Salt as a New Fluorescent Dye for Identification of Amyloid Deposits in Myocardium of mdx Mice

The aim of this study was to develop a new method for the detection of amyloid deposits in laboratory animals using an analogue of Congo red synthesized on the basis of diaminofluorene. The analogue is disodium salt of 2,7-(1-amino-4-sulfo-2-naphthylazo)fluorene (DSNAF). Myocardial samples from mdx mice of both sexes aged 1–1.5 years (n = 8) were used as the material for this study. The main result of this study was the development of an optimal protocol for amyloid staining with DSNAF. It has been shown that the sensitivity and specificity of amyloid detection by this method is comparable with Congo-red staining. The clear advantages of using DSNAF are stability of staining, high fluorescence intensity of amyloid deposits, and total lack of background fluorescence, which greatly simplifies the procedure of quantitative evaluation of obtained results. The method of amyloid staining with DSNAF is characterized by simplicity and good reproducibility. Further research will show the possibility to apply this method for diagnosis of amyloidosis in the practice of clinical research.