Tris-buffered saline

Tris-buffered saline (TBS) is a buffer solution used in biological and biochemical research. It is a mixture of Tris (tris(hydroxymethyl)aminomethane) and saline (sodium chloride), and it is often used as a washing buffer in immunolabeling techniques, such as Western blotting and ELISA tests, as well as in other applications requiring a stable pH environment.

Composition

Tris-buffered saline is composed of a Tris base, sodium chloride (NaCl), and water. The pH of the solution is adjusted to a desired level (commonly pH 7.4) using hydrochloric acid (HCl). The concentration of Tris and NaCl can vary depending on the specific application, but a common formulation is 50 mM Tris, 150 mM NaCl, pH 7.4.

Preparation

To prepare 1 liter of TBS with a pH of 7.4:

1. Dissolve 6.05 g of Tris base and 8.76 g of sodium chloride in 800 mL of distilled water.
2. Adjust the pH to 7.4 by adding concentrated hydrochloric acid (HCl), usually about 20-30 mL.
3. Make up the volume to 1 liter with distilled water.
4. Sterilize the solution by filtration or autoclaving, if necessary, for the intended application.

Uses

Tris-buffered saline has a wide range of uses in the laboratory, including:

• As a washing buffer for immunostaining procedures, helping to remove excess antibodies and non-specifically bound proteins.
• In molecular biology for nucleic acid and protein handling.
• As a diluent for antibody and antigen solutions in immunoassays.
• In cell culture applications to maintain physiological pH.

Advantages

The use of TBS in biological experiments offers several advantages:

• It provides a stable pH environment, which is crucial for maintaining the activity of enzymes and the integrity of protein structures.
• The ionic strength of TBS can reduce non-specific binding in immunoassays, improving the specificity and sensitivity of detection.
• It is compatible with a wide range of biological samples and experimental conditions.

Limitations

While TBS is widely used, it has some limitations:

• It may not be suitable for all applications, especially those sensitive to the ionic strength or pH of the buffer.
• Tris can interfere with certain biochemical reactions, such as those involving aldehyde fixation.

Alternatives

For applications where TBS is not suitable, other buffers such as PBS (phosphate-buffered saline) may be used. The choice between TBS and PBS often depends on the specific requirements of the experiment, including the sensitivity to pH changes and ionic strength.

See Also

• Buffer solution
• Western blot
• ELISA
• Immunostaining