Tailor-Made Dyes for Fluorescence Correlation Spectroscopy (FCS)

Abstract

Two new fluorescent labels are presented that are optimized for excitation with He/Ne laser and red diode lasers. Application in FCS and labeling of proteins and oligomers are demonstrated. A strong rise of quantum yield and emission life time upon binding to biomolecules are characteristic features of the dyes.

An in vitro characterization study of new near infrared dyes for molecular imaging

“…The spectral position of their absorption and emission bands following the order of DY-676 < DY-681 < DY-731 < DY-751 < DY-776 < ICG ( Fig. 3 and Table 2) is determined by the length of the polymethine chain and the electron density at the benzopyrylium-type end group, that increases in the order of DY-731 < DY-751 < DY-776 for the pentamethine dyes [21,42]. Intriguingly with respect to the desired application are the red absorption and emission bands of the trimethine dyes DY-676 and DY-681 and the pentamethine DY dyes in comparison to known symmetric cyanine dyes of similar polymethine chain length and to the heptamethine ICG.…”

“…1 and Table 2). Both dyes are equipped with the same N-bridged benzopyrylium entity that, among the DY dyes studied, seems to favor p-p-interactions between adjacent dye molecules [42]. Mainly responsible for the generally observed fluorescence enhancement in the presence of BSA seems to be a BSA-bindinginduced rigidization of the dye molecules, reducing rotations around single bonds in the polymethine chain and excited state cistrans isomerization, most likely in combination with the prevention of dye aggregation in the case of DY-676 and DY-776, that display the strongest enhancement factors, see Table 2.…”

Long-wavelength fluorescence lifetime labels

“…Examples of cyanine dyes with increased sensitivity for their local environment exhibiting an increase in fluorescence intensity and lifetime upon binding to proteins (e.g., bovine serum albumin, BSA) are DY-630 and DY-635 [68] while indocarbocyanine dyes with a dependence of their cis/trans isomerization rate on the viscosity of the surrounding medium are reported in [69,70]. Lee et al have investigated the fluorescence lifetimes of a number of cyanines in relation to their structure [71].…”

Study of molecular events in cells by fluorescence correlation spectroscopy

“…1) In many applications of FCS the exobiotic under investigation is not intrinsically fluorescent, and hence has to be labelled with a fluorophore. Addition of a fluorophore may change the biological and/or physicochemical properties of the substance in such a way that it no longer shows characteristics of the parental compound [170,171]. Therefore, fluorescent probes have to be selected carefully to induce minimal perturbation in the system under investigation [34, 172 -175].…”