Presentation Information
[23p-1BN-8]The adsorption ability of the CNT-binding aptamer measured by electrochemical method
〇Huanwen Han1, Ting-Chieh Chu1, Naofumi Okamoto2, Masakazu Nakamura2, Ichiro Yamashita1 (1.Osaka Univ., 2.NAIST)
Keywords:
Electrochemical Impedance Spectroscopy (EIS),Peptide Aptamer,CNT-binding Peptide
We proposed a novel CNT/protein/CNT junction for thermo-electric nanodevice. The outer-surface of a cage shaped protein was genetically modified to bind to CNT and heterojunctions were fabricated. This CNT/protein/CNT structure can modify the properties of CNT composites.[1] We used the “Ph.D.-12” phage display system for the aptamer SELEX (Systematic evolution of ligands by exponential enrichment) and panning out CNT aptamers with high CNT-affinity. We used the MEIJO eDIPS and TUBALL SWCNT 75% for the CNT-binding aptamer SELEX and got 4 peptide aptamers with 12 amino acids (named Y1-4). The selected aptamers had similar hydrophobic distribution and alpha helix structures were predicted.[2]
The binding ability assessment by the QCM was difficult for these short peptides and we employed the sensitive label-free electrochemical method using the carbon screen-printed electrodes (SPE, Yoshida Co., Ltd. Figure 1) First, the binding performances were evaluated by using cyclic voltammetry (CV).[3] Peak separation DEp showed their adsorption ability. Following the CV measurements, we carried out electrochemical impedance spectroscopy (EIS) measurements to evaluate the aptamer-target interaction. The measurements were performed in PBS solution containing 1 mM ferricyanide and 1 mM ferrocyanide. After equilibration 1 mg/ml, 3 mg/ml, 10 mg/ml and 30 mg/ml peptide were added sequentially. For all peptides, the charge transfer resistance (Rct) increased in proportion to concentration. Figure 2(a), (b) showed Rct increase ratio (RI) normalizing the first Rct as 1. Y1 showed the highest RI, followed by Y2, Y3, and Y4 showed the lowest RI. These results indicated that Y1 had the highest affinity for carbon surface, which was consistent with CV results. EIS measurements successfully evaluated the aptamer binding ability.
The binding ability assessment by the QCM was difficult for these short peptides and we employed the sensitive label-free electrochemical method using the carbon screen-printed electrodes (SPE, Yoshida Co., Ltd. Figure 1) First, the binding performances were evaluated by using cyclic voltammetry (CV).[3] Peak separation DEp showed their adsorption ability. Following the CV measurements, we carried out electrochemical impedance spectroscopy (EIS) measurements to evaluate the aptamer-target interaction. The measurements were performed in PBS solution containing 1 mM ferricyanide and 1 mM ferrocyanide. After equilibration 1 mg/ml, 3 mg/ml, 10 mg/ml and 30 mg/ml peptide were added sequentially. For all peptides, the charge transfer resistance (Rct) increased in proportion to concentration. Figure 2(a), (b) showed Rct increase ratio (RI) normalizing the first Rct as 1. Y1 showed the highest RI, followed by Y2, Y3, and Y4 showed the lowest RI. These results indicated that Y1 had the highest affinity for carbon surface, which was consistent with CV results. EIS measurements successfully evaluated the aptamer binding ability.