Figure 9. Imaging strategies using bioorthogonal probes.

A) Sugar analogs bearing bioorthogonal groups illuminate bacterial glycans on target species. The sugars GlcNAc and MurNAc are depicted by blue squares and purple hexagons, respectively. B) Clickable muramic acid derivatives fluorescently labeled the peptidoglycan in Lactobacillus acidophilus. Reproduced with permission from DeMeester et al.¹³⁵ C) Labeling bacteria via bioorthogonal probes alongside fluorescent antibiotics allows the differential imaging of Gram-negative and Gram-positive bacteria in vivo. D) Selective labeling of Gram-negative bacteria by 8-azido-8-deoxy-Kdo (8AzKdo, yellow hexagon) and Gram-positive bacteria by fluorescent vancomycin in the gut microbiome. Reproduced with permission from Wang et al.¹³⁹