%0 Journal Article
%T Study on Electrochemical Insulin Sensing Utilizing a DNA Aptamer-Immobilized Gold Electrode.
%A Kubo I
%A Eguchi T
%J Materials (Basel)
%V 8
%N 8
%D Jul 2015 24
%M 28793466
%F 3.748
%R 10.3390/ma8084710
%X We investigated an insulin-sensing method by utilizing an insulin-binding aptamer IGA3, which forms an anti-parallel G-quadruplex with folded single strands. Spectroscopic observation indicates that some anti-parallel G-quadruplex bind hemin and show peroxidase activity. In this study, the peroxidase activity of IGA3 with hemin was confirmed by spectrophotometric measurements, i.e., the activity was three-times higher than hemin itself. IGA3 was then immobilized onto a gold electrode to determine its electrochemical activity. The peroxidase activity of the immobilized IGA3-hemin complex was determined by cyclic voltammetry, and a cathodic peak current of the electrode showed a dependence on the concentration of H₂O₂. The cathodic peak current of the IGA3-hemin complex decreased by binding it to insulin, and this decrease depended on the concentration of insulin.