||This article may be too technical for most readers to understand. (August 2012)|
|ATC code||D08, R02|
|Jmol-3D images||Image 1|
|Molar mass||364.45 g/mol|
237–243 °C (decomposes)
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Cetrimonium bromide ((C16H33)N(CH3)3Br, cetyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, CTAB) is one of the components of the topical antiseptic cetrimide. The cetrimonium (or hexadecyltrimethylammonium) cation is an effective antiseptic agent against bacteria and fungi.
It is a cationic surfactant. Its uses include providing a buffer solution for the extraction of DNA. It has been widely used in synthesis of gold nanoparticles (e.g., spheres, rods, bipyramids). It is also widely used in hair conditioning products.
As any surfactant, it forms micelles in aqueous solutions. At 303 K (30 °C) it forms micelles with aggregation number 75-120 (depending on method of determination, usually average ~95) and degree of ionization α (fractional charge) 0.2–0.1 (from low to high concentration).
The standard constant of Br- counterion binding to the micelle at 303 K (30 °C) is K° ≈ 400. This value is calculated from Br- and CTA+ ion selective electrode measurements and conductometry data by using literature data for micelle size (r = ~3 nm), extrapolated to the critical micelle concentration. However, it varies with total surfactant concentration so it is extrapolated to the point at which the concentration of micelles is zero)
The closely related compounds cetrimonium chloride and cetrimonium stearate are also used as topic antiseptics, and may be found in many household products such as shampoos and cosmetics, while cetrimonium bromide, due to its high cost, is only found in select cosmetics.
Use of CTAB in protein electrophoresis 
Because of the broad distribution of negative charges in glycoproteins, these form broad, fuzzy bands in SDS-PAGE (Laemmli-electrophoresis). This can be avoided by using positively charged detergents like CTAB  instead of the negatively charged SDS. Proteins can be blotted from CTAB-gels in analogy to western blots ("eastern blot"), and CTAB-PAGE can be used as second dimension after IEF. Myelin-associated high hydrophobic protein can be analyzed using CTAB 2-DE.
See also 
- Laemmli, UK (1970). "Cleavage of structural proteins during the assembly of the head of bacteriophage T4". Nature 227 (5259): 680–5. PMID 5432063.
- Buxbaum, Engelbert (2003). "Cationic electrophoresis and electrotransfer of membrane glycoproteins". Analytical Biochemistry 314 (1): 70–6. doi:10.1016/S0003-2697(02)00639-5. PMID 12633604.
- E. Buxbaum: Cationic electrophoresis and eastern blotting. In: B.T. Kurien & R.H. Scofield (ed): Protein blotting and detection – Methods and protocols, (Meth. Mol. Biol. 536), Dordrecht (Humana) 2009, ISBN 978-1-934115-73-2, pp. 115–28
Further reading 
- Merck Index, 11th Edition, 1989.
- Drug information
- Household Products data base for cetrimonium chloride
- Household Products data base for cetrimonium bromide