1,9-Dimethylmethylene blue is a fluorescent dye that can be used for detection of sulfated glycosaminoglycans[1].
References
[1] Farndale RW, et al., A direct spectrophotometric microassay for sulfated glycosaminoglycans in cartilage cultures. Connect Tissue Res. 1982;9(4):247-8. DOI:10.3109/03008208209160269