Trimethine cyanine dyes as fluorescent probes for amyloid fibrils: The effect of N,N′-substituents

The strongest fluorescent response (up to 70 times) and the same sensitivity to aggregates of both proteins were exhibited by the dye D-51 carrying N-sulfoalkyl group. The studied cyanines allow the detection of fibrillar aggregates in the wide range up to 0.8 to 300 μg/ml and permit monitoring the protein aggregation kinetics with high reproducibility. The modification of trimethine cyanine dyes by functional substituents in N,N′-positions is suggested as a tool for the design of fluorescent molecules with the enhanced fluorescent sensitivity to the fibrillar aggregates of proteins.