- Phosphate-buffered saline (PBS) is one of the most suitable biological buffers, extensively used in cell biology and biochemistry laboratory.
- PBS is a water-based physiological balanced salt solution, which is isotonic and non-toxic to the cells.
- All the physiological balanced salt solutions have been derived from the salt solution originally described by Sydney Ringer (1885).
- The first balanced salt solution to be developed specifically for supporting the metabolism of mammalian cells was Tyrode's solution.
- One of the earliest formulations of phosphate-buffer based salt solution was developed by Dulbacco, and is called Dulbacco's phosphate-buffered saline (DPBS).
- Since then, the recipe of phosphate-buffered saline was modified and now several formulations exist and are in use.
- Most of the PBS formulations contain sodium chloride, potassium chloride, sodium phosphate dibasic and potassium phosphate monobasic. Some formulations do not contain potassium chloride.
- Though several formulations exist, they have physiological range of osmolarity (280-286 mOsm/kg) and pH (7.2 - 7.6).
- Sodium chloride (and potassium chloride) is added to maintain the osmolarity of the PBS.
- Sodium phosphate dibasic and potassium phosphate monobasic constitute phosphate buffer system. Sodium phosphate monobasic and sodium phosphate dibasic can also be used as phosphate buffer system. PBS without potassium chloride often use sodium phosphate monobasic and dibasic as buffer system.
- Phosphate buffer system is one of the buffer systems (others are protein buffer system and bicarbonate buffer system), operated in our body fluid.
- Depending on the applications, many supplements can be added in the PBS. Most comman supplements are tween-20, EDTA, calcium, magnesium, BSA, fetal bovine serum (FBS), phenol red, glucose, and pyruvate.
|Common formulations of PBS
- Dulbacco's Phosphate Buffered Saline (DPBS)
- PBS with potassium chloride
- 137 mM NaCl, 2.7 mM KCl, 10 mM Na2HPO4.2H2O, 1.8 mM KH2PO4 (Reference: Sambrook, J., Fritsch, E.F., and Maniatis, T. (1989). Molecular Cloning : A laboratory Manual, 2nd Edition.)
- 137 mM NaCl, 2.7 mM KCl, 8 mM Na2HPO4, 2 mM KH2PO4 (Reference: Invitrogen, Catalog # AM9624-AM9625)
- PBS without potassium chloride
- PBS supplemented with calcium and magnesium
- 137 mM NaCl, 2.7 mM KCl, 10 mM Na2HPO4, 1.8 mM KH2PO4, 1mM CaCl2.2H2O, 0.5 mM MgCl2.6H2O (Reference: CSHL Protocols)
- DPBS supplemented with calcium and magnesium