A Photo- Switchable Signal Chain for Superoxide Detection using a CDSE/ZNS- Quantum Dot Modified Gold Electrode

By means of CdSe/ZnS-quantum dots immobilised on gold electrodes a photo-switchable arrangement for the direct protein electrochemistry of cytochrome c was developed. Under illumination a photocurrent was detected as a result of an electron transfer from the electrode to the photo-excited quantum dots and further to the redox protein in solution. This current was found to be dependent on the concentration of cytochrome c. Thus light can serve as a switch for the protein detection in solution ("On"- situation), whereas in the dark electron transfer is strongly inhibited ("Off"- situation). The results provide the basis for the detection of protein-analyte interactions and for the development of a light-addressable protein array.