Staining Buffer (BSA)

Staining Buffer (BSA) is an antibody diluent and cell wash buffer optimized for immunofluorescent staining of viable or fixed single‑cell suspensions. It contains BSA as a protein carrier to minimize non‑specific binding of antibodies and fluorochromes to target cells. The buffer also includes sodium azide (NaN₃), a metabolic inhibitor, which prevents patching and capping of cell surface antigens. Additionally, sodium azide, in combination with cold temperature maintenance, inhibits antigen redistribution (e.g., shedding or internalization) induced by antibody crosslinking, thereby preserving the fluorescent signal intensity of stained cells during subsequent flow cytometric or fluorescence microscopy analysis. To avoid interference in biotin/avidin‑based indirect staining protocols, the buffer is formulated without biotin, calcium, magnesium, and EDTA.