Développement d’un biocapteur optique à tyrosinase de truffe (Terfezia leonis Tul.) immobilisée sur gel de silice pour le dosage du catéchol en solution
Hicham Gouzi, Saida Leboukh, Yahia Harek
كلية العلوم-جامعة أبو بكر بلقايد - تلمسان · الجزائر
Catechol is widely used in many manufacturing industry, but has been recognized as a toxic andcarcinogenic to humans and animals. Therefore, it is necessary to have a sensitive, less expensive, simpleand reproducible analytical method for catechol detection. Conventional analytical methods such asspectrophotometry, capillary electrophoresis, voltammetry, chromatography and chemiluminescence haveseveral disadvantages thus limiting their use for the determination of this pollutant. Actually, immobilizedtyrosinase biosensors have received a great attention in the analytical field for the determination of phenolsin solution. This work aims to develop an optical biosensor using a crude extract of desert truffle (TerfezialeonisTul.) as an enzymatic source of tyrosinase. The biosensor is constructed by the immobilization oftyrosinase crude extract in a bi-layered silica gel film prepared by dip-coating of an alkoxide/colloidal silicasolution containing the enzyme on glass slide. Encapsulation has a moderate effect of the enzyme optimal pHstability but largely increases its thermal stability. Immobilized enzymes have a higher substrate affinitytowards catechol (KMapp = 0,3mM) but smaller maximum conversion velocity (VMaxapp). The opticalbiosensor showed a good reproducibility and provides a linear response for catechol in the concentrationrange of 50–400 μM with a limit of detection 52 μM. AFM studies show that the enzymes affect the silicagel structure, preventing further deposition of additional layers. The optical biosensor with desert truffletyrosinase can be considered as a promising tool for catechol analysis in pharmaceutical and environmentalfields.