Based On SI-ATRP Imidazole Cation Functionalized Carbon Nanotubes Research Of Sensors

In this paper, we developed a new type sensor through non-covalentintermolecular interaction (π-π stacking interaction, electrostatic interaction andhydrogen bond interaction). It has been used to develop new-style sensors to detectbioactive molecule (thrombin，PPi and DNA). Details:(1) The surface-initiated atom transfer radical polymerization reaction principle(SI-ATRP) was used to grafting the poly imidazole cation chain (Pim) from thesurface of the carbon nanomaterials (MWNTs and graphene). X-ray photoelectronspectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR)characterization were used to confirm the successful modification of Pim. In addition,the Pim-CNTs composites were characterized by scanning electron microscope(SEM), transmission electron microscopy (TEM) and thermal gravimetric analysis(TGA). Because of the positive charges on the surface of Pim-CNTs, the Pim-CNTshave a good dispersibility, the water dispersion of Pim-CNTs has excellent stability.So they can be used to develop the signal-on fluorescence sensor and signal-offelectrochemical sensors.(2) Based on the surface-initiated atom transfer radical polymerization (SI-ATRP)imidazole cation functionalized carbon nanotubes (Pim-CNTs), there are somemolecular weak interactions between Pim-CNTs and fluorescein-labeledthrombin-aptamer (FAM-TA)(such as π-π stacking, electrostatic interactions andhydrogen bonding, etc.). Pim functionalizated CNTs sensitized the fluorescenceresonance energy transfer (FRET) between CNTs and FAM-TA. Thereby, a lowerlimit of detection of TB fluorescence detection was achieved. Compared with thetraditional fluorescent sensor used of carbon nanomaterials, the surface of Pim-CNTsis coverd with positive charges, good dispersion, without adding a dispersing agent,can be more efficiently performed with FAM-aptamer FRET, thus realizing the lowbackground and low detection limits (LOD=2.79pM) detection of thrombin. InsteadPim-graphene with FAM-ssDNA-aptamer validate the principle, also realizing lowdetection limit (LOD=250pM) measurement of tcDNA.(3) Based on the surface-initiated atom transfer radical polymerization (SI-ATRP)imidazole cation functionalized carbon nanotubes (Pim-CNTs), there are weakinteractions between Pim and potassium ferricyanide (K3Fe(CN)6) or single-strandednucleic acid molecule (such as π-π stacking, electrostatic interactions and hydrogen bonding, etc.). The electrochemical sensor (Fe(CN)63-/Pim-CNTs/GCE) was preparedto detect nucleic acids by replacement of Fe(CN)63-. Meanwhile, there are weakintermolecular interactions (hydrogen bonding and electrostatic interactions) betweenPim and pyrophosphate ion (PPi), the competitive effects between PPi and Fe(CN)63-were used to build a replacement-type PPi electrochemical sensors. This methodrealizes the electrochemical detection of the non-electrochemically active molecular(nucleic acids and PPi).