Cell Labeling

Cell labeling refers to the visualization of cells and the identification of cellular structures, while more sophisticated cell labeling allows the tracking of nucleic acids and proteins in living cells to study the various biochemical processes. In general, cells can be labeled in multiple ways, including some of the most basic laboratory techniques, such as Gram staining, or more complex techniques, such as using fluorescent dyes or fluorescent fusion proteins. In addition, many studies have applied click chemistry to cell labeling in recent years, which has driven the development of the biological and medical fields.

Applications

• Cell labeling by CuAAC click reaction

Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction has the potential to be applied to cell labeling since both azide and alkyne groups can be appended to biomolecules without altering their function or metabolic processing. However, the Cu(I) catalyst is considered toxic, which may be attributed to the reactive oxygen species produced by Cu, ascorbate, and atmospheric oxygen. A water-soluble accelerating ligand tris (hydroxypropyltriazolyl) methylamine (THPTA) was introduced into the CuAAC click reaction by Hong et al^[1], which has been shown to rapidly label mammalian cells in culture with no loss in cell viability (Scheme 1). This procedure extends the application of CuAAC click reaction to the exterior of living cells.

Scheme 1. Cell labeling by CuAAC click reaction.

• Cell labeling by photo-triggered click reaction

Photo-triggered click reaction is a type of copper-free click reaction, which does not require a cytotoxic metal catalyst and thus offers new opportunities for living cell labeling. Poloukhtine and co-workers have recently demonstrated that the irradiation of cyclopropenones results in the regeneration of the corresponding dibenzocyclooctynes, which then undergo catalyst-free cycloadditions with azides to generate corresponding triazoles under ambient conditions. In situ light activation of a cyclopropenone linked to biotin made it possible to label living cells expressing glycoproteins containing N-azidoacetyl-sialic acid^[2].

Scheme 2. Cell labeling by photo-triggered click reaction.

What Can We Do?

Alfa Chemistry has a strong research foundation in the field of cell labeling by click chemistry. We have ability to help you explore the various applications of click chemistry and provide you with related click chemistry reagents, technical advice and services. If you have problems, please don't hesitate to contact us.

References

1. Hong, V.; et al. Labeling live cells by copper-catalyzed alkyne-azide click chemistry. Bioconjugate Chemistry. 2010, 21: 1912-1916.
2. Poloukhtine, A.A.; et al. Selective labeling of living cells by a photo-triggered click reaction. Journal of the American Chemical Society. 2009, 131: 15769-15776.