N3-L-Dab(Boc)-OH

The EdU incorporation assay measures DNA synthesis by adding the thymidine analog 5-ethynyl-2′-deoxyuridine to cells or tissues, where it is incorporated into newly synthesized DNA during S phase. Incorporated EdU is detected by copper-catalyzed azide-alkyne cycloaddition, in which a fluorescent azide covalently reacts with the ethynyl group on EdU, allowing S-phase cells to be detected by fluorescence microscopy, flow cytometry, or high-content imaging. EdU detection does not require DNA denaturation or anti-BrdU antibody access, which preserves sample structure and improves compatibility with immunostaining and multiparameter cytometry compared with BrdU-based detection. EdU can be cytotoxic in a cell-type- and exposure-dependent manner, so pulse duration, concentration, and continuous-labeling designs should be validated for each cell type.

Double or multiplex chromogenic IHC detects two or more protein targets in the same FFPE tissue section by repeated antigen-antibody binding, enzyme-linked detection, chromogen deposition, image capture, and, for higher-plex workflows, removal or destaining before the next staining cycle. Chromogenic readouts are generated as colored precipitates at antigen sites, enabling evaluation of marker expression, cell phenotype, and spatial relationships in preserved tissue architecture. Classic examples include MICSSS, which performs iterative chromogenic IHC staining, scanning, and destaining on a single slide, and p16/Ki-67 dual staining, which uses chromogenic co-detection to identify cervical cells with combined cell-cycle deregulation and proliferation signals.