Mechanism of Action

Sodium caseinate holds core value in immunodiagnostics due to its ability to effectively reduce non-specific reactions, thereby enhancing detection accuracy. This is primarily based on the following two characteristics:

Blocking Non-Specific Sites: Sodium caseinate is a protein that can preferentially bind to non-specific sites (e.g., on solid-phase carriers or membranes) not occupied by antibodies in the immunoassay system. This binding prevents the non-specific adsorption of target proteins or antibodies to these sites during subsequent detection steps, which is key to eliminating false-positive results .

Maintaining Colloidal Stability: In gold immunochromatography techniques, sodium caseinate molecules are in a dispersed state in solution and can exert a repulsive effect on gold-labeled complexes. This provides a skeletal framework that helps disperse the colloidal gold particles, thereby maintaining the colloidal stability of the gold-labeled probes and preventing their non-specific aggregation .

Application Scenarios

Based on the above principles, sodium caseinate is widely used in various immunoassays:

Gold Immunochromatography Assays: This is a common technology used in rapid test strips (e.g., pregnancy test strips, certain infectious disease test strips). In such products, sodium caseinate is used as a blocking agent and stabilizer, directly helping to eliminate false-positive bands and ensure result reliability .

Immunoblotting (Western Blot): In this type of protein analysis, sodium caseinate is often formulated into blocking buffers. It is used to block sites on the transfer membrane not bound by the target protein, significantly reducing background noise and making the target protein bands clearer and more distinct .

Enzyme-Linked Immunosorbent Assay (ELISA): Although not explicitly mentioned in the search results, based on its blocking properties, sodium caseinate can also be an option as a component of blocking buffers for microplates in ELISA experiments, following a similar principle to immunoblotting .

Solution Preparation: Sodium caseinate is easily soluble in water, with a commonly used preparation concentration of 1%-5%. It is recommended to use high-purity deionized water and dissolve it with slow stirring .

pH Environment: Its aqueous solution typically has a neutral pH (6.0-7.5). Care must be taken to avoid use under acidic conditions, as exposure to acid causes casein to precipitate, leading to loss of function .

Storage Conditions: It should be sealed and stored in a dry, cool environment. Storage at room temperature is generally recommended, but protection from moisture is essential .