Attachment of nickel hexacyanoferrates nanoparticles on carbon nanotubes: Preparation, characterization and bioapplication

The successful attachment of nickel hexacyanoferrate nanoparticles to carbon nanotubes through a simple, two-step procedure is reported. Histidine can be covalently linked to the carbon nanotube surface, which can then be used as interlinker for the binding of nickel hexacyanoferrate nanoparticles. A detailed investigation by Fourier transform infrared spectra (FT-IR), transmission electron microscopy, UV–vis and electrochemistry was performed in order to elucidate the preparation process and properties of the nanocomposites. Abundant nanoparticles were found attached onto the carbon nanotube surface and the nanocomposites are highly stable. Additionally, the nanostructure exhibits more efficient electron transfer ability and larger electrochemical response towards hydrogen peroxide as compared to the nanoparticles and carbon nanotubes physically mixed together. With the immobilization of cholesterol oxidase onto the nanostructure modified electrode surface, a biosensor that responds sensitively to cholesterol has been constructed. In pH 6.98 phosphate buffer, an almost interference free determination of cholesterol has been observed at −0.2 V versus SCE with a linear range from 0.005 to 3 mM and response time <20 s.