Quantum dots modified electrode and its application in electroanalysis of hemoglobin

In this work, quantum dots (QDs) have been successfully applied in the preparation of chemically modified electrode (CME) in the electrochemical determination (ECD) of proteins. Poly (N-vinyl-2-pyrrolidone) (PVP)-capped CdS quantum dots (PCQDs) were synthesized from CdCl2 and Na2S in the presence of PVP. Characteristics of the PCQDs were studied by TEM, UV–Vis spectrum and FT-IR spectrum. Results showed that the PCQDs were small size, 2–4 nm, with homogenous distributions. The PCQDs were also proved to have good biocompatibility by UV–Vis spectrometry. To our best knowledge, it is the first time to modify the PCQDs onto the surface of glassy carbon electrode to fabricate a PCQDs CME. The PCQDs CME possessed rather good electron transport characteristic that was consistent with the higher charge detaching efficiency of CdS quantum dot resulting from its quantum size effect. The electrochemical behaviors of hemoglobin on this PCQDs CME have been investigated by cyclic voltammetry (CV). Novel reduction responses were observed for hemoglobin on the PCQDs CME in aqueous solutions, which could not be obtained on bare GCE. In addition, the results of flow injection analysis (FIA) showed the high stability and reproducibility of the PCQDs CME. The peak current was a linear function of concentrations in the range 1.0 × 10−8 to 2.0 × 10−5 M for Hb, with detection limit of 5.0 × 10−9 M. The FIA–ECD system has been successfully applied to assess the Hb content of clinic blood samples with advantages of sensitiveness, speediness, easy control and small sample-consumption.