Quantum dots-multiwalled carbon nanotubes nanoconjugate-modified pencil graphite electrode for ultratrace analysis of hemoglobin in dilute human blood samples

A novel molecularly imprinted polymer, selective for human hemoglobin, was immobilized on the surface of CdS quantum dots-multiwalled carbon nanotubes nanoconjugate-modified pencil graphite electrode. The fabricated sensor was found to be water-compatible and biologically benign, since the molecular imprinting was exclusively carried out in water, without any protein denaturation and electrode fouling. Notably, the pencil graphite electrode modified with merely a nanoconjugate matrix might involve the onset possibilities of electrode passivation and protein denaturation. However, a polymer coating onto the nanoconjugate obviated such obstacle while evaluating human hemoglobin in an aqueous environment (pH 4.2). The quantification of the hemoglobin in the dilute whole blood samples varied in the linear range 27.8–444.0 ng mL−1; and the detection limit was obtained as 6.73 ng mL−1 (S/N=3), without any cross-reactivity and false-positives. The proposed sensor can be used as a cost effective sensor for hemoglobin, in clinical settings.