Construction of a l-lysine biosensor by immobilizing lysine oxidase on a gold-poly(o-phenylenediamine) electrode

The construction of a l-lysine biosensor on a Si–gold strip electrode (SGSE) is described in this study. The construction comprises (a) the formation of poly(o-phenylenediamine, o-PD) membrane on the electrode surface via electropolymerization and (b) the immobilization of lysine oxidase on the gold/poly(o-PD) electrode with glutaraldehyde. The behavior of the gold/poly(o-PD) electrode against H2O2 and lysine, as well as the repeatability of the electropolymerization and the time stability of the polymer were studied. The study showed that the electropolymerization procedure is repeatable, and that the polymer is quite stable for at least 40 days. The biosensor showed a linear calibration curve in the range 0.01–1×10−5 M (0.1–10 μM) lysine. The interfering effect of other amino acids on the biosensor performance was also studied and amperometric selectivity coefficients were calculated. The biosensor responded mainly against tyrosine and cysteine, while the response to phenylalanine, arginine, histidine and ornithine was very low. By changing the electropolymerization conditions, the effect of interferents was further reduced.