Tide Fluor™ dyes by AAT Bioquest are a series of highly water-soluble fluorescent reagents designed to label oligonucleotides and peptides for molecular imaging and diagnostic applications. Conjugates produced with Tide Fluor™ dyes exhibit exceptionally bright fluorescence and better photostability outperforming most conventional and proprietary dye-labeled conjugates, including fluorescein, cyanine, and most Alexa Fluor^® dye-labeled conjugates. For optimum results in FRET biosensing, Tide Fluor™ dyes should be used collectively with complementary non-fluorescent Tide Quencher™ dyes. The efficient FRET relationship between Tide Fluor™-Tide Quencher™ pairs facilitates the detection of molecular interactions within live cells at the nanometer range.

Tide Fluor™ dyes are available in 10 distinct emission colors with absorption spectra that span the UV to infrared spectrum and match the primary wavelengths of common excitation sources. The significantly stronger fluorescence and higher photostability exhibited by Tide Fluor™ dyes and their conjugates minimize photobleaching effects caused by high light intensities and long-term illumination giving researchers plenty of time to observe and capture images. Tide Fluor™ dyes are made available in a variety of conjugation chemistries, including amine-reactive (e.g., succinimidyl ester), thiol-reactive (.e.g., maleimide), and click chemistry formats (e.g., alkyne and azide) for labeling N-terminal, C-terminal, and cysteine residues. For in-synthesis labeling (e.g., solid-phase synthesis), Tide Fluor™ 1 CPG (Cat No. 2240 and 2241) and Tide Fluor™ 3 phosphoramidite dyes (Cat No. 2274) are available in either 100 mg or 100 µmoles unit sizes, respectively. In addition, Tide Fluor™ 3-labeled FMOC amino acids are available for directly labeling aspartic acid, glutamic acid, and lysine residues during FMOC solid-phase synthesis.

Tide Fluor™ dyes share nearly identical fluorescence spectra with common fluorophores, making upgrading to Tide Fluor™ dyes effortless. Traditional fluorophores and their conjugates can easily be replaced with spectrally similar Tide Fluor™ dyes without affecting instrument configuration (e.g., lasers and optical filters). For example, spectra of Tide Fluor™ 2WS and Tide Fluor™ 3WS dyes match those of fluorescein and Cy3 dyes and can be detected with standard fluorescein or TRITC/Cy3 filter sets, respectively. Each of the Tide Fluor™ dyes and their equivalents is listed below in Table 2.

Together Tide Fluor™ and Tide Quencher™ dyes can be used to produce highly sensitive FRET probes for a variety of applications, including enzyme studies, pharmacological drug screening, and qPCR analysis. Since the absorbances of Tide Quencher™ dyes are well-tuned to quench their Tide Fluor™ equivalent, substrates are completely non-fluorescent, and the potential for any background interference resulting from nonsensitized acceptor excitation is eliminated. Separating the two dyes either by proteolysis (i.e., FRET peptides) or nucleic acid hybridization (i.e., FRET nucleotides) restores fluorescence characteristic of the Tide Fluor™ label.