Sugars, or glycans, play a crucial role in biology—from cell signaling and recognition to interactions with pathogens. Changes in glycosylation are also associated with diseases including cancer. But studying glycans poses a major challenge: because many glycans are highly water-soluble, or hydrophilic, they cannot easily cross the cell membrane and must be modified with a hydrophobic moiety—a water-repelling chemical group—and prepared and delivered using potentially harmful solvents.