Alkaline Phosphatase-Catalyzed Amplification of a Fluorescence Signal for Flow Cytometry

Despite the expanding use of flow cytometry, its detection limit is not satisfactory for many antigen proteins with low copy numbers. Herein, we describe an alkaline phosphatase (AP)-based technique to amplify the fluorescence signal for cell staining applications. We designed a fluorescent substrate that acquires membrane permeability upon dephosphorylation by AP. By using the substrate, the fluorescence signal of cells in flow cytometry could be successfully amplified to give a much stronger signal than the cells labeled using a conventional fluorophore-modified antibody.