Multiwall carbon nanotube–CdS/hemoglobin multilayer films for electrochemical and electrochemiluminescent biosensing

This paper presents both electrochemical and electrochemiluminescence (ECL) detections based on the layer-by-layer (LBL) films fabricated with hemoglobin (Hb) and the optimal nanocomposite containing multiwall carbon nanotubes (MWCNTs) and CdS quantum dots (QDs). Hb and the MWCNT–CdS nanocomposite were electrostatically assembled on the chitosan (CS) modified glassy carbon electrode (GCE) forming with up to six bilayer films. Our results on cyclic voltammograms (CVs) revealed that the redox peak currents of Hb at the six-bilayer film ({MWCNT–CdS/Hb}6) modified GCE were the largest. Hydrogen peroxide (H2O2) could be stably detected using the six bilayer films modified GCE with a wide linear range from 0.125 μM to 1.20 mM. Nitrite (NO2−) could also be determined through CdS QDs of the multilayer films based on stable ECL intensities with a linear range from 0.60 μM to 0.80 mM.