Methylene Blue, which belongs to the phenothiazine family of dyes, is a unique dye with a variety of useful properties. Despite its high extinction coefficient in the visible region (81,000 L/mol.cm), it is weakly fluorescent due to its high rate of intersystem crossing from the S1 excited state to the T1 triplet state. This property makes it an excellent photosensitizer, and it has been used extensively to produce highly reactive singlet oxygen. Methylene blue has the ability to both intercalate in duplex DNA, preferring G:C over T:A base pairs, and can act as an electrochemical redox probe. Methylene blue has also been shown to be unmatched in performance as a redox-active reporter for electrochemical biosensors.
Earlier, we introduced Methylene Blue C3 Phosphoramidite but this product proved to have quite limited stability and has been discontinued. As an alternative option, we introduced Methylene Blue NHS Ester to allow researchers to label amino-modified oligonucleotides with this interesting dye. With the encouragement and technical expertise of Carole Chaix and her colleagues at the University of Lyon, we decided to prepare an alternative structure that seemed to have a much superior stability profile - Methylene Blue II Phosphoramidite. Fortunately, this structure did indeed prove more stable and we are now able to offer again a Methylene Blue Phosphoramidite.
Methylene Blue II is covered under patent applications FR12 51739 and PCT/FR2013/050356 and is sold under license from the University of Lyon.