Click Chemistry has been used prominently in pharmaceutical and biotech R&D. It has become increasingly popular due its biocompatibility and its faster reaction speeds.1 Click Chemistry can be categorized as one of three generations.

The 1st generation of Click Chemistry uses a Cu(I) catalyst in the reaction between a terminal alkyne and an azide. Although the coupling reaction is successful, the addition of a Cu(I) catalyst can cause damage to the biomolecule.

First Generation Click Chemistry

The 2nd generation Click Chemistry utilizes the reaction between cyclooctyne and an azide via strain-promoted azide-alkyne Click Chemistry. This reaction is copper-free and proceeds due to the high-activation energy of the strained molecule. In this copper-free Click Chemistry, commonly used reagents include DBCO, OCT and BCN. The use of reagents such as BCN, prevents the production of regioselective mixtures.

2nd Generation Click Chemistry

The 3rd generation of Click Chemistry involves the ligation between a tetrazine and trans-Cyclooctene (TCO) without the use of a Cu(I) catalyst. The omission of the Cu(I) catalyst is ideal for in vivo cell labelling while still enabling a high-speed reaction.2 This has been found to allow protein modification at lower concentrations.3

Advertisement #3 

The introduction of a PEG linker to Click Chemistry reagents enhances its water-solubility properties and makes it more convenient for biolabeling in aqueous buffers. 

3rd Generation Click Chemistry


1 Biocojug Chem. 2008 December; 19(12):2297-2299. Doi: 10.1021/bc8004446.

2 Biocojug Chem. 2008 December; 19(12):2297-2299. Doi: 10.1021/bc8004446.

3 J. Am. Chem. Soc. 2008, 130, 13518-13519.

Advertisement #4
Previous articleWhat does PEGylation Chemistry look like?
Next articleMersana Presents Updated Data about its Dolasynthen Platform and Synthemer Scaffold
Avatar photo
BroadPharm® is a leading customer-focused biotech company in San Diego, California. We are dedicated to manufacturing and supplying high purity PEG linkers, Click Chemistry Reagents and advanced Bio-labeling reagents such as Dye Labeling and Biotin Labeling compounds to our clients worldwide. In addition, we also offer IP-protected custom synthesis for our clients in the pharmaceutical and biotech industries. We provide timely technical support to address our client’s need and offer technical advice for the best use of our new products. Founded in 2009, BroadPharm® takes our customer needs as our highest priority. We have over 2,000 discrete, high purity PEG reagents in stock which can be shipped to our clients immediately. PEG is an abbreviation for Polyethylene Glycol which consists of repeating ethylene oxide units. Unlike traditional PEGs, all of BroadPharm®’s PEG products represent a specific, single chemical structure with high purity. Each product is synthesized and purified using BroadPharm®’s proprietary advanced technology and characterized by modern NMR and LC/MS. BroadPharm®’s PEG products offer many advantages over traditional linkers such as increased water solubility, reduced aggregation and low immunogenicity. These PEG reagents have been widely used in bioconjugation, antibody-drug conjugates (ADCs) therapeutic, drug delivery and diagnostics field. With our strong expertise in modern chemistry, innovative & novel PEG technology and state-of-the-art equipment, BroadPharm® can help our customers to accelerate their research through cost-effective and efficient solutions.