H-aggregates of the cyanine dye Cy5 are formed during covalent linkage to the cationic macromolecule Poly(allylamine) (PAH).The nonfluorescent H-aggregates strongly restrict the usage of the dye for analytical purposes Dimensional Wall Art and prevent a quantitative determination of the labeled macromolecules.The behavior of the H-aggregates has been studied by investigation of the absorption and fluorescence spectra of the dye polymer in dependence on solvent, label degree and additional sulfonate groups.H-aggregate formation is caused by an inhomogeneous distribution of the Cy5 molecules on the polymer chain.The H-aggregates can be destroyed by conformational changes of the PAH induced by 5 SENS CONDITIONER interactions with polyanions or in organic solvents.
It has been found that the polymer labeling process in high content of organic solvents can prevent the formation of H-aggregates.The results offer a better understanding and improvement of the use of the Cy5 dye for labeling purposes in fluorescence detection of macromolecules.