| Abstract
| - A rapid, homogeneous aptamer-based bioanalysis isreported for the sensitive detection of immunoglobulin E(IgE) using fluorescence polarization (FP). 5‘-End-labeledD17.4 DNA aptamer was used for IgE detection basedon the anisotropy differences of the labeled ligand. Twodifferent fluorophores, fluorescein and Texas Red, wereused to analyze IgE in the low-nanomolar range with highspecificity. Measurable anisotropy changes were observedwith a short equilibration time. Analysis of the bindingdata reveals a possible cooperative binding process insolution. The nature of the fluorophore clearly influencesthe sensitivity of the analysis more than the tether lengthused for the dye conjugation. The local fluorophore motionis seen to influence the sensitivity of the FP probesignificantly. Texas Red is seen to be relatively moresensitive for this approach and has apparently favorabledye−DNA interactions, and a limit of detection of 350 pMwas obtained. Significant temperature dependence of theFP responses has been observed in this work. Ioniccomposition of the binding buffer also influences the assaysensitivity. The results confirm the promise and potentialof similar homogeneous assays for aptamer-based bioanalysis.
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