ABSTRACT
Control experiments show that the oligonucleotide-sensing assembly reveals high specificity and selectivity. Treatment of the (13)-functionalized electrode with the HRP conjugate (16), but without the interaction with the DNA analyte (14), yields only a minute change in the electron-transfer resistance. Also, the sensing interface, for example, the (13)-functionalized monolayer electrode, was interacted with a solution that included the DNA fragment (14a) and the biotin-labeled oligonucleotide (15). The oligonucleotide (14a) corresponds to the normal gene sequence in which the 7-base
mutation leads to the Tay-Sachs genetic disorder. After treatment of the sensing interface with the complex between (14a) and (15), the system was subjected to the biocatalytic precipitation process using the avidin-HRP conjugate (16). No noticeable changes in the electron-transfer resistances at the electrode were observed, implying that the lack of formation of the ds-oligonucleotide-DNA (analyte) complex with the sensing interface prevented the subsequent formation of the precipitate layer on the electrode.
