Click chemistry (Click chemistry), this concept was originally derived from the observation of natural products and biosynthetic pathways. It was a synthetic concept introduced by chemist K B Sharpless in 2001. It was introduced by Professor Sharpless, 67, who became the Nobel Prize winner in chemistry in 2001.
“Click chemistry” generally forms covalent bonds by the interaction of azide and alkyne, which has the advantages of high efficiency, stability, and high specificity, etc. The reaction is not affected by PH and can be carried out in water under normal temperature conditions, even in living cells.
Furthermore, the introduced groups’ types of click chemistry reagents can be divided into the following types:
1.Application of azide modification reagent(non-fluorescent azide)
1)AmdU (5-azidomethyl-2′-deoxyuridine)— A nucleoside containing azide, which can be incorporated into nascent DNA by cell polymerase. And the azide group attached to the DNA in this way can then be modified with alkynes or cycloalkynes.
2)Azide-PEG2-aldehyde— A linker with azido and an aliphatic aldehyde moiety.
3)Azide-PEG3-OH— It is a bifunctional molecule with an azide group, primary alcohol, and a hydrophilic linking group in between.
4)NHS azidobutyrate acid ester— It is used to an azido-labeled activated ester for peptides and proteins
5)Biotin PEG3 azide— The biotin azide and affinity probe can be labeled with biotin for click chemistry.
6)Chloro-PEG3-azide— It is a heterobifunctional linker with reactive chloride, used for the alkylation of various nucleophilic groups.
7)Iodine-PEG3-azide— Iodine-PEG3-azide contains highly reactive iodide functional groups, which can make various C-, O-, N-, S-centered nucleophiles Alkylation with other nucleophiles.
2.Use of alkynyl modification reagents(non-fluorescent alkynes)
1)Acetylene hydrazide— A bifunctional reagent containing alkynyl and hydrazide functions. And it reacts with aldehydes and ketones, then the alkynyl group is coupled with various azides through the CuAAC reaction.
2)Alkyne maleimide— It used to connect alkynes, functional groups, proteins, peptides, and other molecules with SH(thiol)groups, including cysteine residues.
3)Alkynes NHS esters (NHS hexanoate)— Alkynes NHS esters are used to biomolecular markers with alkyne groups for copper-catalyzed click chemistry.
4)Biotin alkynes— It is a reactive affinity label that can be attached to biomolecules through click chemistry.
5)DBCO NHS ester— azobenzocyclooctyne(DBCO, ADIBO)reagent has NHS ester function and can connect cyclooctyne to various molecules.
6)EdU (5-ethynyl-2′-deoxyuridine)— A nucleoside that can be incorporated into replicated DNA by cellular enzymes. And the DNA contained in the cell can be developed through a click chemistry reaction with the fluorescent dye azide to reveal cell proliferation.
7)STP hexanoate— alkynyl activated ester, used to modify the amino group. STP ester groups are an excellent alternative to NHS ester functional groups.
8)STP valerate— An activated ester used to introduce alkynes into peptides/proteins.