Electrogenerated chemiluminescence and electrochemical bi-functional sensors for H2O2 based on CdS nanocrystals/hemoglobin multilayers

A novel bi-functional sensor, based on CdS nanocrystals (NCs) and hemoglobin (Hb) multilayer films, designated as {Hb/CdS}_n, modified glassy carbon electrode (GCE) by layer-by-layer (LbL) assembly, has been presented. The electrogenerated chemiluminescence (ECL) and electrochemical properties of {Hb/CdS}_n have been investigated in detail. Hb in the multilayer films can enhance the stability of electrogenerated species of CdS NCs, and CdS NCs can also promote the direct electron transfer between Hb and GCE. As a consequence experimentally, the multilayer films modified GCE is suitable to be used as a bi-functional sensor, ECL sensor and electrochemical sensor, to determine H₂O₂ in obviously different concentration. In high concentration of H₂O₂, this sensor as an ECL sensor shows a linear response from 15 μM up to 18 mM. In the lower concentration of H₂O₂, it as an amperometric one shows two linear ranges of amperometric responses to the concentration of H₂O₂ ranging from 6.0 to 31.0 μM and from 6.0 μM down to 40 nM with a detection limit of 20 nM, based on the high stability of ECL by {Hb/CdS}_n and the excellent electrocatalytical ability of Hb to H₂O₂. Thus, {CdS/Hb}_n modified electrodes would have a great merit to expand the application of biosensors to life science and environmental science.