Copper quantum cluster-polypyrrole composite film based zero current chronopotentiometric sensor for glutathione

We report, for the first time, a potentiostatically deposited copper quantum cluster (CuQC) and CuQC-polypyrrole composite film modified copper disc electrode prepared under the seemingly unlikely conditions of deposition at +0.8 V vs. Ag/AgCl for 100 s from tetrabutylammonium bromide (R4N+Br-) and, R4N+Br- and pyrrole solutions. By employing zero current chronopotentiometry, the electrode response was linear from 10(-6) to 10(-4) M of glutathione with a limit of detection of 2.6 x 10(-7) Mand a precision of 4.3% (at 10(-6) M). Spectral and morphological characterizations revealed that each quantum cluster is an aggregate of similar to 2 nm size consisting of several sub nm sized particles. Furthermore, the designed glutathione sensor is selective with respect to amino acids, ascorbic acid, uric acid and glucose. The quantification of glutathione in human urine was successfully tested and recoveries on standard addition were found to be quantitative.