Fig. 1. The schematic representation of the POSE concept. (a) The metabolic incorporation of ManNAz into cell surface glycoproteins as SiaNAz. (b) The bio-orthogonal reaction of the DBCO-FeBABE probe with the SiaNAz group through copper-free click chemistry. (c) The oxidation of proteins in the sialic acid environment by hydroxyl (and other) radicals generated from the reaction between the FeBABE probe and hydrogen peroxide.
