Search

Thick film electrode based biosensors containing Trametes versicolor (TvL) and Aspergillus niger (AnL) laccases and Agaricus bisporus tissues (AbT) were developed for the determination of phenolic compounds and the measurement was based on oxygen consumption in relation to analyte oxidation. The electrodeposited organic polymer; polyaniline was used as a matrix for the immobilization in the preparation of thick film sensors. The systems were calibrated for different phenolic substances. A linearity was obtained in concentration range between 0.4 and 6.0 μM phenol, 0.2 and 1.0 μM catechol, 2.0 and 20.0 μM l-DOPA for TvL based biosensor; for AnL based enzyme electrode 0.4 and 4.0 μM phenol, 0.4 and 15 μM catechol, 0.4 and 6.0 μM l-DOPA; for AbT electrode 1.0 and 10 μM phenol, 0.4 and 1.6 μM catechol, 1.0 and 10 μM l-DOPA, respectively, in the response time of 300 s. Furthermore, as well as sample application and accuracy, optimum pH, temperature and thermal stabilities of the proposed systems were also detected. [Copyright &y& Elsevier]

Amperometric biosensors using laccase from Trametes versicolor as a bioelement were developed for 2,4-dichloro phenoxy acetic acid (2,4-D). Laccase enzyme was immobilized by gelatin and glutaraldehyde onto a Clark oxygen probe and screen printed electrodes (SPEs). Amperometric and chronoamperometric measurements were carried out with the biosensors. First, the effect of laccase activity on the biosensor performances was investigated for both biosensors, and then optimum pH and temperature and also thermal stability of the biosensors were tested. In addition, the detection ranges of some phenolic compounds were obtained by the help of calibration graphs of them. In repeatability studies, variation coefficients and standard deviations for both biosensors were also calculated by the studies done for this purposes. Finally, the biosensors were applied to the determination of 2,4-D in a real herbicide sample. [ABSTRACT FROM AUTHOR]

Abstract: Two biosensors based on Trametes versicolor laccase (TvL) were developed for the determination of phenolic compounds. Commercial oxygen electrode and ferrocene-modified screen-printed graphite electrodes were used for preparation of laccase biosensors. The systems were calibrated for three phenolic acids. Linearity was obtained in the concentration range 0.1–1.0μM caffeic acid, 0.05–0.2μM ferulic acid, 2.0–14.0μM syringic acid for laccase immobilised on a commercial oxygen electrode and 2.0–30.0μM caffeic acid, 2.0–10.0μM ferulic acid, 4.0–30.0μM syringic acid for laccase immobilised on ferrocene-modified screen-printed electrodes. Furthermore, optimal pH, temperature and thermal stability studies were performed with the commercial oxygen electrode. Both electrodes were used for determination of a class of phenolic acids, achieving a cheap and fast tool and an easy to be used procedure for screening real samples of human plasma. [Copyright &y& Elsevier]

A biosensor was developed by immobilizing laccase onto mercury thin film electrode (MTFE) by means of gelatin that is then crosslinked with glutaraldehyde. Mercury thin film (MTF) was deposited onto glassy carbon electrode (GCE) and the obtained biosensor was utilized for the determination of phenolic compounds. The measurement was based on the amperometric detection of oxygen consumption in relation to analyte oxidation. The optimum experimental conditions for the biosensor were investigated and the system was calibrated for both catechol and phenol. A linear relationship between sensor responses and analyte concentrations was obtained in concentration range between 0.5 × 10 -6 – 5.0 × 10 -6 M for catechol and 2.5 × 10 -6 – 2.0 × 10 -6 M for phenol, respectively. Mercury thin film was also formed onto the surface of screen printed graphite electrodes and applied for the catechol detection. The linearity was observed in concentration range between 2.5 × 10 -6 – 3.0 × 10 -5 M. [ABSTRACT FROM AUTHOR]