Amytracker™ fluorescence is one magnitude brighter than Congo Red. The affinity of Amytracker™ is in the nM range and thus, Amytracker™ is typically used at several fold lower concentrations. In a comparative study using human amyloidosis tissue, Amytracker™ detected amyloid deposits in 15% of Congo Red negative samples. While the pathological relevance of Congo Red negative deposits is currently unclear, Amytracker™ staining might give an indication of earlier states of disease.
Unlike Congo Red, Amytracker™ does not bind to collagen or other cytoskeletal proteins.
In the APP/PS1 and APP23 mouse models of Alzheimer's disease, Amytracker™ stains early fibrils already after 6 months, while Congo Red stains mainly mature fibrils showing up after 12 months in the APP/PS1 mouse model.
Amytracker™ has also been utilize to detect disease-associated protein aggregates, such as prion proteins and inclusion bodies, which go undetected by Congo red.