BIOTIN LABELED ANTIBODIES Preparation Purified antibodies are labeled with an N-hydroxysuccinimide ester of biotin which contains a 7-atom spacer (-aminocaproic acid). When compared to conjugates prepared with biotin without a spacer arm, the use of biotin with the spacer arm imparts increased sensitivity and specificity on the antibody-biotin conjugate. Form   Specificity Biotin-labeled antibodies are supplied at a concentration of 0.5 mg/mL in PBS/NaN3. To ensure lot-to-lot consistency, each biotin-labeled antibody is tested by ELISA and/or flow cytometry for conformance with characteristics of a standard reference reagent. Storage and Stability Biotin-labeled products can be stored for several months at 2-8°C without appreciable loss of working titer. For long-term storage of the conjugates, the labeled antibodies should be aliquoted and frozen at -20°C. Avoid repeated freezing and thawing. Applications ELISA Immunoblotting Flow cytometry Immunohistochemistry Immunocytochemistry Working Dilutions Immunoassay Working Dilution ELISA 1:5,000 - 1:20,000 Cell/tissue staining for light microscopy 1:50 - 1:200 Cell/tissue staining for IF microscopy 1:50 - 1:200 Western blotting 1:1,000 - 1:2,000 Slot/dot immunoblotting 1:1,000 - 1:2,000 Cell staining for flow cytometry 1:50 - 1:200 The dilutions given are only recommendations. The optimal dilution for particular applications should be determined by the investigator.