Streptavidin toxicity

Avidin/streptavidin biotin. Sensitive. Laborious. Toxic chromogens. Need to block endogenous biotin activity. 

Electroactive labels introduced into DNA also possess electrochemical signals at less extreme potentials than intrinsic DNA responses. An example is electroactive osmium tetraoxide with 2,2 -bipyridine bound to free 3 -ends of the ss regions created by a DNA repair enzyme exonuclease III, which responds to the extent of DNA damage [25]. The technique is capable of detection of one lesion per 10 nucleotides in supercoiled plasmid DNA. DNA-hybridization biosensors were proposed for studies of DNA damage by common toxicants and pollutants where voltammetric transduction was achieved by coupling ferrocene moiety to streptavidin linked to biotinylated target DNA [26]. 

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