AF 488 TFP ester | CAS 2133404-55-2

AF 488 TFP ester is a reactive fluorescein-based dye designed for covalent fluorescent labeling via N-hydroxysuccinimide (TFP) ester chemistry. This amine-reactive form enables rapid coupling to primary amines on proteins, peptides, and many biomolecule scaffolds, generating stable fluorescent conjugates for imaging and fluorescence-based assays. Its green emission from the fluorescein family is commonly leveraged in standard fluorescence microscopy and flow cytometry workflows where FITC-like channels are used.

1. Protein And Antibody Labeling

AF 488 TFP ester is widely used to prepare fluorescently labeled proteins and antibodies for fluorescence microscopy, immunostaining workflows, and binding assays. Researchers typically use the TFP ester to conjugate to lysine residues and N-termini on antibodies, enzyme proteins, and affinity reagents, producing conjugates that can be tracked in solution or on targets such as cell-surface antigens. The resulting AF 488-labeled biomolecules are routinely incorporated into assay development for fluorescence readouts, where consistent labeling chemistry is needed to compare binding behavior across experimental conditions.

2. Fluorescence Microscopy Staining

AF 488 TFP ester supports fluorescent staining and cellular imaging by enabling covalent tagging of biomolecular probes used for microscopy. In fixed-cell or fixed-tissue workflows, investigators often label secondary antibodies, receptor-binding proteins, or other targeting ligands with AF 488 to visualize localization patterns under standard fluorescein/GFP filter sets. Because the dye is introduced through amine-reactive coupling, the reagent is frequently selected when robust, covalent labeling is preferred over noncovalent fluorescent dyes, improving retention of signal during washing steps that accompany microscopy sample preparation.

3. Flow Cytometry Conjugate Preparation

AF 488 TFP ester is commonly employed to generate flow cytometry dyes by covalently labeling antibodies and protein reagents used for immunophenotyping and fluorescence-based binding measurements. The TFP ester format allows controlled attachment to primary amines on antibody fragments and whole IgG, yielding fluorescent conjugates that can be used to quantify marker expression by fluorescence intensity. Researchers also use AF 488-labeled reagents to build multicolor panels, taking advantage of the fluorescein emission region to align with common cytometer laser and filter configurations used for FITC-like channels.

4. Fluorescent Bioassay Reagent Building

AF 488 TFP ester is used in fluorescence assay development to produce labeled assay components such as detection antibodies, reporter proteins, and fluorescent standards. By covalently attaching AF 488 to biomolecular reagents, assay developers can create consistent fluorescence readouts for binding assays, washing-based immunoassays, and platform-specific fluorescence measurements. The amine-reactive TFP ester chemistry is particularly useful when the labeled component must withstand typical assay handling steps, including buffer exchanges and incubation/wash cycles, while maintaining a stable fluorescent signal for quantitative comparison.