Electronic structure of cyclodextrin-carbon nanotube composite films

Abstract

The electronic structures of two kinds of cyclodextrin-carbon nanotube (αCD-CNT and γCD-CNT) composite films are investigated by using (angular dependent) photoelectron spectroscopy to gain insight as to why the αCD-CNT and γCD-CNT composite films show different performances in biosensor applications. The γCD-CNT composite film is likely to have the CD localized on the surface rather than in the bulk of the film, while αCD-CNT has CD relatively more concentrated within the bulk of selvedge region of the film, rather than the surface. The results indicate that the CD, of the γCD-CNT composite, may be more bioactive, and possibly a better sensor of biomolecules due to the favorable surface position compared with that of αCD-CNT. The valence band of αCD-CNT and γCD-CNT show little difference from the CNT film except for a density of states, originating from CD, evident at a binding energy near 27 eV below Fermi level, meaning that there are few or no redox interactions between the CD and the CNT. The absence of a redox interaction between the CD and the CNT permits a clear electrochemical response to occur when guest biomolecules are captured on the composites, providing a route to biosensor applications.