Bioorthogonal Reactions in Chemical Biology

Bioorthogonal reactions are chemical transformations that proceed selectively and rapidly within living systems without perturbing native biochemical processes. Since their inception, these methods have revolutionised our ability to probe and manipulate biomolecules in situ, enabling precise labelling, imaging and control of proteins, nucleic acids, carbohydrates and lipids. Central to their utility is an exceptional combination of orthogonality, biocompatibility and fast kinetics, which permits selective bond formation or cleavage under physiological conditions. Key reaction platforms include strain-promoted azide–alkyne cycloaddition, inverse-electron-demand Diels–Alder chemistry and bioorthogonal cleavage strategies, each of which can be tuned through structural innovation in reagents such as cycloalkynes, tetrazines and trans-cyclooctenes. Advances in catalyst design have further extended the repertoire to include transition-metal-mediated transformations in living cells, opening avenues for in vivo prodrug activation, biomaterial assembly and controlled release of reporters. Collectively, bioorthogonal chemistry underpins a broad spectrum of applications—from dynamic imaging of cellular processes to targeted therapy—and continues to shape our understanding of complex biological systems.

Research from Nature Portfolio

Recent studies have demonstrated the feasibility of in vivo catalysis by non-natural metal systems. Nano-encapsulated palladium particles have been shown to accumulate selectively in tumours and to activate prodrugs with minimal off-target toxicity, thereby inhibiting tumour growth in mouse models. Complementary work has combined enzymatic supramolecular self-assembly with a bioorthogonal decaging trigger to achieve synergistic, spatiotemporally controlled prodrug activation in cancer cells, resulting in high tumour inhibition with favourable safety profiles. In parallel, dual transition-metal catalysis using water-activatable gold(I) and ruthenium(II) complexes has been translated into living mammalian cells, allowing orthogonal C–C bond formation and enabling the construction of artificial enzymatic pathways without interfering with endogenous metabolism.

Bioorthogonal Reactions in Chemical Biology publication trend

The graph below shows the total number of articles in bioorthogonal reactions in chemical biology across all publications each year (not limited to Nature Index journals).

Technical terms

Bioorthogonal reaction: A chemical transformation that occurs inside living systems without interfering with native biochemical processes.

Strain-promoted azide–alkyne cycloaddition (SPAAC): A catalyst-free ligation between cycloalkynes and azides driven by ring strain.

Inverse-electron-demand Diels–Alder (IEDDA): A cycloaddition between electron-deficient dienes (e.g. tetrazines) and strained dienophiles with exceptionally fast kinetics.

Prodrug activation: The bioorthogonal release of an active drug from a chemically caged precursor within a biological environment.

Transition-metal catalyst: A metal complex that promotes non-natural transformations under physiological conditions, enabling bioorthogonal bond formation or cleavage.

References

1. Late-Stage Functionalization of Living Organisms: Rethinking Selectivity in Biology. Chemical Reviews (2024).
2. Inverse electron demand Diels–Alder reactions in chemical biology. Chemical Society Reviews (2017).
3. Strain-Promoted 1,3-Dipolar Cycloaddition of Cycloalkynes and Organic Azides. Topics in Current Chemistry (2016).
4. Nano-palladium is a cellular catalyst for in vivo chemistry. Nature Communications (2017).
5. Synergistic enzymatic and bioorthogonal reactions for selective prodrug activation in living systems. Nature Communications (2018).
6. Concurrent and orthogonal gold(I) and ruthenium(II) catalysis inside living cells. Nature Communications (2018).
7. Unleashing the Power of Bond Cleavage Chemistry in Living Systems. ACS Central Science (2021).