A carboxylated graphene and aptamer nanocomposite-based aptasensor for sensitive and specific detection of hemin.

A unique nanocomposite was crafted by grafting hemin-binding-aptamer (HBA) onto carboxylated graphene (COO-GR). Infrared spectroscopy, Raman spectroscopy and diffuse reflectance spectra suggested that -NHCO- covalent bonds were formed between HBA and COO-GR. The resulting COO-GR/HBA functionalized electrode was used as a novel label-free biosensor. The square wave voltammetry was employed to realize the selective and specific detection of hemin. The obtained aptasensor possessed excellent performance with a detection limit of 0.64 nmol L(-1) (S/N=3) and a linear range from 1 to 150 nmol L(-1). Moreover, COO-GR was shown to be a promising candidate in making aptasensors, carrying advantages over graphene in terms of the simplicity of sensor preparation and the reduction of background noise.