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Different fluorescent compounds can intercalate nucleic acid chains, both single and double-stranded. Ethidium bromide (EtBr) is likely the most well-known DNA dye. However, reports on EtBr carcinogenicity and mutagenicity have potentiated the development of safer dyes, such as GelRed™, GelGreen™, GelStar™ or Viridin VIVID™ with comparable or better sensitivity in terms of nucleic acid staining (Table 1).


Table 1. Excitation and emission wavelengths of different fluorescent dyes for nucleic acid staining


A spectra viewer tool with different fluorophores may be found here.

When considering the light source for excitation and visualisation filters, there are two main commercially available choices: UV-light transilluminators or Blue light transilluminators (Dark readers) (Figure 1).

UV-light transilluminators are commonly available with maximum light output at three different wavelengths, 254, 312 and 356 nm being that a higher wavelength is safer for the user, however a lower wavelength usually provides better image resolution when visualising the gel.

Blue light (Dark reader) transilluminators have been gaining more and more popularity as a safe alternative to UV-light for gel visualisation and band extraction. Due to their blue light source with maximum light output between 400 and 500 nm, they present some advantages over their UV-light counterparts:

  1. Prevents sample degradation via UV-induced DNA damage
  2. Minimises interference in molecular biology reactions, such as PCR or cloning
  3. It is safer for the user to handle
  4. Exhibits reduced photo-bleaching, increasing fluorescence retention time


Figure 1. UV-light transilluminators or Blue light transilluminators (Dark readers)

For ordering or additional questions on transilluminators and nucleic acid staining, please contact us.