Ethidium Bromide

Ethidium bromide (EtBr) is a fluorescent dye most well-known for its role in visualizing DNA in agarose gels. It is excited by UV light and, when intercalated with DNA, emits intense orange fluorescence at around 205 nm in wavelength. Ethidium bromide can also bind to single-stranded DNA and RNA, although with less intensity. EtBr is a known mutagen and requires safety precautions when handling. It is often added directly to melted agarose prior to gel casting and electrophoresis.