Cetrimonium bromide

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Cetrimonium bromide, commonly called CTAB, is a quaternary ammonium surfactant with a long cetyl (16-carbon) tail. It appears as a white powder that dissolves in water and is used in several areas.

In medicine and cleaning products, CTAB is a key ingredient in the antiseptic cetrimide and is used in DNA extraction buffers because its positive charge helps remove unwanted substances and protects DNA during isolation. In science and materials research, CTAB acts as a template and stabilizer to make gold nanoparticles and mesoporous silica (such as MCM-41), helping to control the size and shape of particles. It is also found in some shampoos and cosmetics, though its higher cost limits its use in many products.

Properties: chemical formula C19H42BrN; melts at around 237–243 °C. In water, CTAB forms micelles, which are tiny clusters that help dissolve oils and interact with cell membranes.

Safety: CTAB can be toxic if swallowed and is harmful to aquatic life. It can irritate skin and eyes. Animal studies have shown potential embryotoxic and teratogenic effects at higher doses. Because of these safety concerns, CTAB is typically used under controlled conditions in labs and specialized manufacturing, and consumer uses are regulated. The World Health Organization notes CTAB as a purification aid in some vaccine-related processing.