Polyaniline–carbon nanotube composite film for cholesterol biosensor

Nanocomposite film composed of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNT), prepared electrophoretically onto indium tin oxide (ITO)-coated glass plate, was used for covalent immobilization of cholesterol oxidase (ChOx) via N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry. Results of linear sweep voltammetric measurements reveal that ChOx/PANI–MWCNT/ITO bioelectrode can detect cholesterol in the range of 1.29 to 12.93 mM with high sensitivity of 6800 nA mM−1 and a fast response time of 10 s. Photometric studies for ChOx/PANI–MWCNT/ITO bioelectrode indicate that it is thermally stable up to 45 °C and has a shelf life of approximately 12 weeks when stored at 4 °C. The results of these studies have implications for the application of this interesting matrix (PANI–MWCNT) toward the development of other biosensors.