I-Block Reagent is a high purity casein-based blocking reagent. It has better sealing ability than dry milk and BSA. Unlike other casein-based blocking reagents, I-Block reagent is essentially biotin-free. I-Block reagents are detected in assays using Tropix substrate and alkaline phosphatase conjugates and used as blocking reagents in membrane-based and immunoassay applications.

The recommended working concentration is 0.2% (w/v) for detection of nucleic acids on neutral or positively charged nylon membranes and for immunization on membranes (nitrocellulose, PVDF or neutral nylon) detection and protein detection. For protein detection on positively charged nylon membranes (such as TropilonPlus membranes), the recommended concentration is 3%. I-Block blocking solutions are prepared in Tris or phosphate buffered saline buffer under heat (40-50°C).

This casein-based blocking reagent can be used with Western-Light, Western-Light Plus, Western-Star, ELISA-Light, Southern-Light and Southern-Star detection systems.