Tom Brown, Professor of Nucleic Acid Chemistry, Departments of Chemistry and Oncology, University of Oxford said: "The concept of click chemistry, initially pioneered by Barry Sharpless 20 years ago aided by his colleagues Valeri Fokin and M.G. Finn, has been transformative in many areas of chemistry, materials science, biology and medicine. It has given rise to new highly functional materials, has catalysed important pharmaceutical developments and has been influential in many areas of chemical biology.
“The archetypal click reaction is Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC), the copper-catalysed version of the original Huisgen reaction. The CuAAC reaction makes exclusively 1,4-disubstitted 1,2,3-triazoles. It can be looked upon as a molecular ‘superglue’ or ‘molecular lego’ to join molecules together. It was discovered simultaneously by Sharpless and Meldal. It is an extremely efficient reaction, and crucially it is orthogonal to most other chemical reactions, and can be carried out in most media including water. These properties, particularly the fact that it is ‘invisible’ to other functional groups an molecules, make it incredibly flexible and broadly applicable. Applications are almost endless, for example it has been of enormous value to our own research in the nucleic acids field.
“The remarkable work of Carolyn Bertozzi has given rise to new types of click reactions that do not require copper catalysis, termed ‘Bioorthogonal click chemistry’. This concept can be used in applications where the CuAAC reaction and related metal ion catalysed reactions are not possible due to the toxicity of the metals. An example of Bioorthogonal click chemistry’ is the SPAAC reaction (Strain-promoted alkyne-azide cycloaddition) involving the reaction of an azide with a strained cyclooctyne. Importantly Bertozzi’s work enables click reactions to be done in living systems. It enables the visualisation of molecules in living cells and organisms, the study of disease processes, and development of new drugs including improvements in drug delivery. It has very been used to great effect in the study of glycans (polysaccharides) that play a major role in all essential functions of the human body, including the immune system.
“This is Sharpless’s second Nobel Prize in Chemistry, a stunning achievement. Anyone who knows him will testify that he is a unique character who is remarkably imaginative and passionate about chemistry.”