β-Cyclodextrin functionalized graphene as a highly conductive and multi-site platform for DNA immobilization and ultrasensitive sensing detection

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.