TY - JOUR A1 - Grabolle, Markus A1 - Pauli, Jutta A1 - Brehm, Robert A1 - Resch-Genger, Ute T1 - Structural control of dye-protein binding, aggregation and hydrophilicity in a series of asymmetric cyanines JF - Dyes and pigments N2 - Aiming at the rational design and the identification of brilliant fluorescent reporters for targeted optical probes and fluorescence assays in biological matrices, we systematically assessed the correlation between dye–protein binding, dye aggregation, and dye hydrophilicity for bioanalytically relevant fluorescent labels. Here, we report on the influence of sulfonic acid groups on dye aggregation and dye–serum protein interactions exemplarily for a family of NIR-emissive cyanine dyes, the DY-67x fluorophores. For highly hydrophobic dyes like DY-675 and DY-676, which show a strong tendency for aggregation in phosphate buffer saline solution, the dye–protein binding constants determined spectroscopically using a 2-state binding model, which considers only protein-bound and unbound dye molecules, can be influenced by the dimerization of the unbound dyes. To consider and quantify this influence, we expanded this common photometric method to a 3-state model that accounts for the presence of dye aggregates in the binding studies. Our results can be exploited for the screening of fluorescent reporters, efficiently providing information on the size of dye–protein interactions and on maximally achievable fluorescence quantum yields in biological systems. KW - Cyanine dye KW - Dye–protein interaction KW - BSA KW - Binding constant KW - Hydrophilicity KW - Aggregation PY - 2014 DO - https://doi.org/10.1016/j.dyepig.2013.11.027 SN - 0143-7208 SN - 1873-3743 VL - 103 SP - 118 EP - 126 PB - Elsevier Ltd. CY - Kidlington AN - OPUS4-30054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -