Figure 6

Evaluation of commercially available streptavidin coated QDs. Commercially available streptavidin coated QDot₆₀₅ (from Invitrogen) were incubated with biotinylated DNA (lane 1) and non biotinylated DNA (lane 2) at a molar ratio of 1:100, for 30 minutes at room temperature. Following the conjugation reaction the DNA-QD mixtures were run on a 1% agarose gel to assess the percentage of QDs capable of efficient biotin-streptavidin conjugation. QDot₆₀₅ were imaged using the ethidium bromide filter set on the UVP iBox Imaging System. As shown, the QDs used in our experiments exhibit great variability in terms of their biotin binding ability (see arrows). Arrow 1 indicates QDs that are unable to bind biotin.