Cells labeled using Click chemistry

Click chemistry is the detection method of choice for samples that would be compromised by direct labeling or antibody-based secondary detection techniques. The click label is small enough to penetrate complex samples easily, and the selectivity and stability of the click reaction provide high sensitivity and low background signal. This gentle sample treatment together with the biocompatible Click-iT Plus reaction means that detection can be multiplexed with expressed proteins such as GFP, protein labels such as R-PE, and a wide range of organic fluorophores.

Browse Invitrogen Molecular Probes products such as Click-iT assay kits and Click-iT tools below to find the product that best fits your experiment.

  • Invitrogen Molecular Probes Click-iT Assay Kits for imaging
  • Invitrogen Molecular Probes Click-iT Assay Kits for HCS
  • Invitrogen Molecular Probes Click-iT Kits for biomolecule capture
  • Invitrogen Molecular Probes Click-iT Kits for flow cytometry
  • Protein and glycan labeling tools
  • Nucleic acid labeling tools
  • Detection tools for standard, low-copper, and copper-free reactions

Find Click-iT kits and other products by application

Cell proliferation

Measure cell proliferation using imaging or flow cytometry


Detect late-stage apoptosis using imaging or flow cytometry

Click-iT technology overview

Click-iT reactions use azides and alkynes as specific binding moieties in a two-step procedure that first labels and then subsequently detects your molecule of interest. Azides and alkynes can be used interchangeably in “click” reactions, so either one can serve as the tagged substrate or be labeled for the detection step.

Small labels

Azides and alkynes are extremely small, inert, and stable moieties that can be incorporated into biological molecules. They are small enough that nucleotides, sugars, or amino acids can be tagged and still continue to function in the cell and incorporate normally into nucleic acids, complex polysaccharides, or proteins.

Small molecules permit:

  • Cellular loading with minimal disruption
  • Normal incorporation into biomolecules

In a typical Click-iT labeling step, a cell is supplied with the azide or alkyne moiety in a tagged molecule and it is incorporated into a cellular biopolymer.

Specific detection

Azides and alkynes bind together in a “click” reaction with high specificity to form stable, inert products. We’ve developed both molecules with fluorescent labels attached, such as Alexa Fluor dyes, to serve as sensitive detection tools that are small enough to penetrate complex samples.

  • Cellular labeling with minimal disruption
  • Specific detection with low background signal

If an azide is incorporated into a cellular protein it can be labeled using an alkyne tagged with an Alexa Fluor dye. Conversely, if an alkyne is incorporated into a cellular protein it can be labeled using an azide tagged with an Alexa Fluor dye.

Minimal denaturation

The copper-catalyzed click reaction links an alkyne with an azide to form a stable inert product. The mild reaction conditions of the Click-iT Plus reagent help preserve the activity of fluorescent proteins, so click reactions can be multiplexed with GFP or R-PE in your detection strategy.