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Labeled peptides find wide application in biochemical and biological studies, in vitro and in living cells. Typical applications are the Fluorescence (or Förster) Resonance Energy Transfer (FRET) analysis of receptor-ligand interactions, protein-protein interactions and the cleavage of substrate molecules.

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This video shows the uptake of Amyloid β-Protein (1-42) by J774 macrophages, obtained from BALB/c mice. The Amyloid β-Protein (1-42) was labeled with Tide Fluor™ 5WS fluorescent dye to enable visualization. The cells were displayed in bright field imaging overlaid with the green fluorescent channel of the peptides. In the beginning of the video, fluorescent particle aggregates appear, and the cells start to internalize them. Subsequently, particle aggregates are becoming visible intracellularly. Ultimately, every cell has taken up some particles that are visible as little green spots inside the cells. As uptake by the macrophages continues, green particles further accumulate within the cells and are visualized as green material intracellularly.

Peptides and Amino Acids Labeled with Dyes and Quenchers – Excellent Performance

The technical and scientific requirements on fluorescent labeled probes and quenchers are manifold and high. Examples are an efficient excitation light absorption and high yield of energy emission by the donor label (dye) as well as a good energy absorption by the acceptor (quencher), in order to reach a high signal-to-noise ratio. This is particularly important under physiological conditions, where often only low dye concentrations can be used. Furthermore, the dyes should have a high photo-stability, in order to minimize bleaching caused by exposure with high light intensities, used for example in microscopy. The choice of the best fluorescent dye and quencher often suffers cost constraints, since proprietary dyes, which can fulfill the scientific requirements, usually are expensive.


Bachem extended its product portfolio by peptides labeled with Tide Fluor™ dyes and, optional, Tide Quencher™ from our newest partner, AAT Bioquest, Inc. These combine the cost advantages of classic fluorescent tags with the performance of proprietary dyes, or even outperform the latter in the relevant characteristics.


Our Custom Synthesis Team will be pleased to advise you on the custom peptide modification of your dye labeled peptides.

 We recently introduced the following Tide Fluor™ products:

Tide Fluor™ Dyes

  • Efficient absorption of excitation light from common light sources
  • Significantly stronger fluorescence, than most conventional or proprietary dyes
  • Significantly higher photo-stability, than most conventional or proprietary dyes


Tide Fluor™ dyes and Tide Quencher™ dye labeled peptides are available as:


  • Carboxylic acids
  • Maleimido-, azido- and alkyne- derivatives
  • Active esters (NHS)
  • Amines


Furthermore, Tide Fluor™ dyes are available with improved water solubility (TFWS).

A product overview can be found in Table 1 and Table 2.

Tide Quencher™ Labels for FRET Purposes

For optimum results in FRET analysis, the Tide Fluor™ dyes should be combined with the proprietary quenchers of the Tide Quencher™ (TQ) range. The emission spectra of the Tide Fluor™ dyes have a great overlap with the excitation spectra of the recommended Tide Quencher™ acceptors (Table 1), leading to an efficient quenching process.


Also in comparison to the majority of classic and proprietary quenchers, Tide Quencher™ labels have:


  • Significantly higher absorption strength
  • Superior quenching efficiency


Like Tide Fluor™ dyes, Tide Quencher™ labels are available with improved water solubility (TQWS).