Bioorthogonal chemistry may enable in vivo imaging for nucleic acids

Fluorescence-based bioimaging is a useful tool for studying biological systems, such as for monitoring protein localization and movement in living organisms. However, the fluorescent proteins used are not suitable for tagging certain biomolecules, such as glycoconjugates, nucleic acids and lipids.

Alamudi et al. provide an overview of recent developments in the usage of azide-based bioorthogonal chemical reporters for cellular imaging applications.

In the review, the authors discuss strategies for the metabolic incorporation of chemically tagged molecular building blocks into cells via cellular machinery systems, and the advantage of using smaller and exogenous bioorthogonally compatible fluorescent probes for visualizing intracellular architectures selectively with high specificity.

The review is structured into two main sections, one dealing with azide-based bioorthogonal reactions that include Staudinger ligation, copper(I)-catalyzed azide-alkyne cycloaddition and strain-promoted azide-alkyne cycloaddition, and one dealing with azide-based labeling strategies for bioorthogonal imaging for proteins, glycans, nucleic acid and lipids.

The authors note several remaining challenges for the method to be fully practical, challenges such as the need for faster reaction rate and higher selectivity, and the improvement of various parameters to increase the imaging speed and resolution for in vivo measurements under native conditions.

“The orthogonal chemistry using azide will realize vivid real-time imaging inside the body, further empowered by tame dye for lower background,” said author Young-Tae Chang.

Source: “Azide-based bioorthogonal chemistry: Reactions and its advances in cellular and biomolecular imaging,” by Samira Husen Alamudi, Xiao Liu, and Young-Tae Chang, Biophysics Reviews (2021). The article can be accessed at http://doi.org/10.1063/5.0050850 .