A bright red fluorescent cyanine dye for live-cell nucleic acid imaging, with high photostability and a large Stokes shift

Abstract

Many probes for nucleic acids are available, but few of them satisfy multiple criteria, particularly high photostability to endure laser scanning. We report a cyanine dye TO3-CN for the first time, synthesised by introducing a CN group to the trimethine chain of the classical red emitting TO-3 dye to improve its photostability, as well as their spectral properties and interaction with nucleic acids. TO3-CN shows excellent light fastness and a large fluorescence Stokes shift (more than 40 nm). Because of its sensitive fluorescence response to nucleic acids with a large fluorescence quantum yield (more than 0.7) and low cytotoxicity, this dye may be a potential candidate for nucleic acid detection in vitro and intracellular fluorescence imaging.

Spectral fine tuning of cyanine dyes: electron donor—acceptor substituted analogues of thiazole orange

“…As seen in Figure 6, the dyes stain both nuclei and cytoplasm, similar to other fluorogenic cyanines. 52, 53 As expected, TO gives brighter staining upon excitation at 488 nm while CH 3 O-TO-CF 3 is significantly brighter for 561 nm excitation.…”

Enhanced Binding Affinity of siRNA Overhang‐Binding Fluorescent Probes by Conjugation with Cationic Oligopeptides for Improved Analysis of the siRNA Delivery Process

“…To this end, we need to improve the probe functions. For example, it would be useful to integrate cyanine dyes with longer emission wavelengths than that of TO, such as TO3 derivatives, as the signaling unit in the probe design, which could reduce the background autofluorescence. As for the binding property, the use of triplex‐forming PNAs to target the RNA duplex near the overhanging structure would lead to improved binding affinity and selectivity of the probe to target siRNAs.…”

ZnII Complexes for Bioimaging and Correlated Applications

“…[60,61] The use of the commerciallya vailable RNA probes, such as Syto RNA-select, presents small Stokes shifts, photobleaching, and high cytotoxicity,r esulting in undesirable back-ground noise attributed to the autofluorescence of endogenous fluorophores. [62][63][64][65][66] Ap ossible solution to this drawback could be offered by the use of two-photon microscopy (2PM). 2PM imaging has the capability to generate autofluorescencefree backgrounds with deeper tissue penetration, which makes it ah ighly suitable technique to selectively target RNA in biological samples.…”