PBS stands for phosphate buffered saline and is often used because it is isotonic to cells.
1x PBS is 137 mM NaCl, 10 mM Phosphate, 2.7 mM KCl, pH 7.4
To make 10x PBS,
- Combine the following:
- 80 g NaCl
- 2 g KCl
- 14.4 g Na2HPO4
- 2.4 g KH2PO4
- 800 mL distilled H2O
- Adjust pH to 7.4 with HCl
- Add H2O to 1L
- Autoclave for 20 minutes on liquid cycle. Store at RT.
- PBST: For some applications (washing) one adds Tween 20 PBS which makes PBST
- Usual concentrations of Tween 20 in TBST are 0.1 or 0.05%.
Another buffer used for washing in immunohistology is PBS Triton, which contains 0.1%-0.3% of the detergent Triton X-100. A 1% Triton X-100 can also be added to fixed tissue sections for 10 minutes (followed by 3 time, 15-minute PBS wash) to permeabilize tissue prior to blocking at the beginning of a immunostaining experiment.