Chemical structure of trans-cyclooctene-taxol (a) and tetrazine-BODIPY FL (b). Confocal microscopy of a kangaroo rat kidney cell after treatment with trans-cyclooctene-taxol followed by tetrazine- BODIPY FL (green). The nucleus is visualized using Hoechst stain (blue). Scale bar: 30 μm. Expansion of the section indicated by the dashed white line. Reprinted with permission from ref 29. Copyright 2010 John Wiley & Sons, Inc.