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Electrochemical Detection

Ferrocene (Fc) and Methylene Blue are attractive electrochemical probes for nucleic acid biosensing because they are stable and convenient to synthesize.

Ferrocene Phosphoramidites

With our ferrocene phosphoramidite, you can directly incorporate the Fc-modification into your oligo to successfully generate electroactive probes. 

Our Fc-phosphoramidite has a structure analogous to our other dT products (eg. amino, dabcyl, biotin, fluorescein etc). 

  • This simplifies its synthesis and delivers the benefits of having a nucleobasic structure consistent with natural DNA-sugar-phosphate backbone 
  • With Fc-modification at the 5-position of the pyrimidine, natural base-pairing to dA will still occur
Method/Incorporation Site Reference
Fc labelling using the conjugation of carboxy-Fc to 5'-amino-modified oligos Electrochemically active DNA probes: Detection of target DNA sequences at femtomole level by high-performance liquid chromatography with electrochemical detection, S. Takenaka, Y. Uto, H. Kondo, T. Ihara and M. Takagi, Anal. Biochem., 218, 436-443, 1994; Ferrocene-oligonucleotide conjugates for electrochemical probing of DNA, T. Ihara, Y. Maruo, S. Takenaka and M. Takagi, Nucleic Acids Research, 24, 4273-4280, 1996; Electrochemical analysis of DNA amplified by the polymerase chain reaction with a ferrocenylated oligonucleotide, Y. Uto, H. Kondo, M. Abe, T. Suzuki and S. Takenaka, Anal. Biochem., 250, 122-124, 1997.]
Internal post-synthetic labelling of DNA probes using a reaction with ferrocenecarboxaldehyde or aminoferrocene Electrochemical detection of sequence-specific DNA using a DNA probe labelled with aminoferrocene and chitosan modified electrode immobilized with ssDNA, C. Xu, H. Cai, P. He and Y. Fang, Analyst, 126, 62-65, 2001.
Direct incorporation into oligonucleotides using Fc phosphoramidites and monomers with a ferrocenyl moiety linked to position 5 of 2'- dU and dC or the 2’ sugar position of dA and dC M. Wiessler and D. Schutte, European Patent WO9709337 (1997) T.Chunlin, US Patent Application US2009/0155795 A1 (2009).Uridine-conjugated ferrocene DNA oligonucleotides: Unexpected cyclization reaction of the uridine base, C.J. Yu, H. Yowanto, Y. Wan, T.J. Meade, Y. Chong, M. Strong, L.H. Donilon, J.F. Kayyem, M. Gozin and G.F. Blackburn, J. Amer, Chem. Soc., 122, 6767-6768, 2000Ferrocene-modified pyrimidine nucleosides: synthesis, structure and electrochemistry, H. Song, X. Li, Y. Long, G. Schatte and H.-B. Kraatz, Dalton Trans., 4696-4701, 2006. 2'-Ribose-ferrocene oligonucleotides for electronic detection of nucleic acids, C.J. Yu, H. Wang, Y. Wan, H. Yowanto, J.C. Kim, L.H. Donilon, C. Tao, M. Strong and Y. Chong, J. Org. Chem., 66, 2937-2942, 2001.

Methylene Blue, Carboxylic Acid, Succinimidyl Ester

Methylene Blue is useful as an electrochemical reporter when conjugated to aptamers.

Our Methylene Blue active ester is used to post-synthetically conjugate the methylene blue moiety with an amine-functionalised biomolecule on substrates such as peptides and oligonucleotides.

While Ferrocene can produce slightly improved signal gain and target affinity compared to Methylene Blue, Fc-based sensors are less stable than their methylene blue counterparts. The level of stability can affect long-term storage, repeatability of electrochemical interrogations, and use in complex biological samples (Kang, Di et al. “Comparing the properties of electrochemical-based DNA sensors employing different redox tags.” Analytical chemistry vol. 81,21 (2009): 9109-13. doi:10.1021/ac901811n)