Yizhen Yang,Feng Gao,Xili Cai,Xiaoning Yuan,Suyu He,Fei Gao,Hongxu Guo,Qingxiang Wang
A versatile nanocomposite containing β-cyclodextrin and graphene (CD–GR) was prepared through a simple chemical reduction method. The characterization experiments show that the nanocomposite remains the flake-like morphology of GR, but its solubility and stability in aqueous solution are greatly improved. Then the nanocomposite was modified at glassy carbon electrode (GCE) surface, and was used as a functional matrix for the covalent immobilization of probe DNA using 2,4,6-trichloro-1,3,5-triazine (TCT) as the crosslinker . Due to the synergetic effect of large surface area of GR and rich hydroxyl of CD, the probe density for the developed biosensor was determined to as high as 3.82×10 13 molecules cm − 2 . Meanwhile, the biosensor shows high hybridization efficiency and hybridization kinetic. When the biosensor was applied for the impedance-based hybridization test, a wide linear range from 1.0×10 −16 to 1.0×10 −12 M and an ultralow detection limit of 3.4×10 −17 M were achieved. The biosensor also displays excellent stability, selectivity , and reproducibility.
Lina Zou,Ying Xu,Peili Luo,Shusheng Zhang,Baoxian Ye
A novel voltammetric sensor, based on DNA immobilized on the surface of an ethylenediamine/polyglutamic (En/PGA) modified glassy carbon electrode (GCE), was constructed and used for determination of dihydromyricetin (DMY). The electrochemical behaviour of DMY at this sensor was investigated in pH 3.6 NaAc-HAc buffer solutions by cyclic voltammetry (CV) and differential pulse anodic voltammetry (DPV). The oxidation of DMY is an adsorption-controlled irreversible process. The oxidation mechanism was proposed and discussed. It was found that the modified electrode exhibited a linear voltammetric response for DMY in the range of 4.0 × 10−8 mol L−1 to 2 × 10−6 mol L−1, with a detection limit of 2 × 10−8 mol L−1. The method was also applied successfully to detect DMY in an ampelopsis sample with satisfactory results.
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