The Invitrogen™ CellBlox™ Blocking Buffer is formulated to block nonspecific binding of Invitrogen™ NovaFluor™ labels with cells. These nonspecific interactions can result in higher background labeling. CellBlox Blocking Buffer is a non-antibody, non-protein–based blocking solution, and should be used every time a NovaFluor dye is used for labeling any cell type to minimize background labeling. (Figure 1)

CellBlox Blocking Buffer is also recommended for use with cyanine-based dyes or cyanine-based tandem dyes to block non-specific interactions with monocytes and macrophages to minimize background labeling. (Figure 2)

Use of CellBlox Blocking Buffer requires minimal change to most flow cytometry staining protocols. Add 5 μL CellBlox Blocking Buffer directly to a cell suspension containing 10³ - 10⁸ cells prior to the addition of an antibody, with 100 μL as a final staining volume. CellBlox Blocking Buffer may be added to an antibody cocktail mixture prior to labeling cells, by adding 5 μL CellBlox Blocking Buffer for every stained sample to be labeled with the antibody cocktail mixture, with 100 μL as a final staining volume.

• Always use CellBlox Blocking Buffer with NovaFluor dyes when labeling cells for best background reduction.
• CellBlox Blocking Buffer is compatible with all fluorophores and with Invitrogen™ LIVE/DEAD™ Fixable Dead Cell Stains.
• CellBlox Blocking Buffer can be used with any fluorophore-antibody conjugate as a high-performance monocyte and macrophage blocking solution.
• CellBlox Blocking Buffer is compatible with other blocking reagents, such as Fc Block, blocking proteins, Brilliant Stain Buffer, and Super Bright Complete Staining Buffer.
• CellBlox Blocking Buffer is not required when labeling antibody-capture beads