Bright, "Clickable" Porphyrins for the Visualization of Oxygenation under Ambient Light

A new group of “clickable” and brightly emissive metalloporphyrins has been developed for the visualization of oxygenation under ambient light with the naked eye. These alkynyl‐terminated compounds permit the rapid and facile synthesis of oxygen‐sensing dendrimers through azide–alkyne click chemistry. With absorption maxima overlapping with the wavelengths of common commercial laser sources, they are readily applicable to biomedical imaging of tissue oxygenation. An efficient synthetic methodology, featuring the stable trimethylacetyl (pivaloyl) protecting group, is described for their preparation. A paint‐on liquid bandage containing a new, click‐synthesized porphyrin dendrimer has been used to map oxygenation across an ex vivo porcine skin burn model. Red light, green light: A group of oxygen‐sensitive, “clickable” metalloporphyrins are bright enough to be seen by the naked eye in the absence of oxygen under ambient light. To demonstrate the ease of use of these sensors, one porphyrin was “clicked” into a biocompatible dendrimer, embedded in a bandage formulation, and used to transdermally map oxygen consumption in a burn model.