PREPARATION, CHARACTERIZATION AND APPLICATION OF ALKANETHIOL SELF-ASSEMBLED MONOLAYERS MODIFIED WITH TETRATHIAFULVALENE AND GLUCOSE OXIDASE AT A GOLD DISK ELECTRODE

摘要

In this work, the results obtained with a gold disk electrode modified with alkanethiol self-assembled monolayers (SAMs), and glucose oxidase (GOD), and the redox mediator tetrathiafulvalene (TTF) immobilized atop are presented. Thus, a gold electrode modified with a mercaptopropionic acid SAM, where GOD and TTF were immobilized by cross-linking with glutaraldehyde, allowed linear calibration curves for glucose, obtained by amperometry in stirred solutions at an applied potential of +0.20 V, in the 5.0 10~(-6) - 1.0 10~(-2) mol L~(-1) range. A detection limit of 1.3 10~(-6) mol L~(-1) and a RSD of 5.2 % (n=10), at a concentration level of 1.0 10~(-4) mol L~(-1), were found. No leaching of the enzyme and mediator is observed during the whole working day. The modified electrode is stable in dry conditions for 24 h and for at least 100 hours if kept in a 4℃ H_2PO_4~-/HPO_4~(2-) buffer solution (pH 7.4).