An optical catechol biosensor based on a desert truffle tyrosinase extract immobilized into a sol–gel silica layered matrix

Abstract

optical catechol biosensor based on a desert truffle tyrosinase extract immobilized into a sol-gel silica layered matrix. AbstractAn optical biosensor for the determination of catechol, a widely used yet toxic and carcinogenic molecule, is proposed using a crude extract of desert truffle (Terfezia leonis Tul.)as an enzymatic source of tyrosinase. The biosensor is constructed by the immobilization of tyrosinase crude extract in a bi-layered silica gel film prepared by dip-coating of an alkoxide/colloidal silica solution containing the enzyme on glass slide. Encapsulation has a moderate effect of the enzyme optimal pH stability but largely increases its thermal stability.Immobilized enzymes have a higher substrate affinity towards catechol but smaller maximum conversion velocity. The optical biosensor provides a linear response for catechol in the concentration range of 50-400 µM and a limit of detection was 52 µM. AFM studies show that the enzymes impact on the silica gel structure, preventing further deposition of additional layers. Comparison with similar dopamine biosensors points out that the impact of encapsulation on enzymatic activity may depend on the considered substrate.

Functionalized Tyrosinase-Lignin Nanoparticles as Sustainable Catalysts for the Oxidation of Phenols

“…As a general procedure, phenols 1 – 4 (0.02 mmol), tyrosinase (540 Units), and ascorbic acid (2 equiv), were placed in PBS 5.0 mL (0.1 M) at 25 °C for 24 h, and the mixture was stirred under O 2 atmosphere. In agreement with previous optimization studies reported in the literature, the experiments have been performed at optimal pH 7.0 [ 43 ]. Oxidations were performed using homogeneous and heterogeneous conditions.…”

“…The K m and V max values measured for catalysts I – IV were of the same order of magnitude as those recently reported for the tyrosinase crude extract of desert truffle ( Terfezia leonis Tul.) after immobilization into a sol-gel silica layered matrix [ 43 ]. In this latter case, catalyst IV showed a K m value (0.25 mM) lower than that observed after the sol-gel encapsulation procedure.…”

Optical biosensor for catechol determination based on laccase‐immobilized anionic polyamide 6 microparticles

“…[11] Different enzymes have been used for biosensors construction, tyrosinase and laccase being among the most used ones. [12][13][14] In contrast to other enzymes, for example, horseradish peroxidase, [15] laccase catalyzes the oxidation of catechol by molecular oxygen, not requiring additional oxidation mediators like hydrogen peroxide, [16] which results in simplification of biosensor design.…”

More than a Confinement: “Soft” and “Hard” Enzyme Entrapment Modulates Biological Catalyst Function

“…The biosensor exhibited a linear response on catechol, but a decreased efficiency upon repetitive use, likely due to enzyme leaching or inactivation. Furthermore, the biosensor was not sensitive enough to the concentration of catechol as the limit of detection was 52 µM, in the upper limit of the acceptable concentration of phenolic compounds in wastewater [66].…”

“…These values are significantly different than those obtained for the soluble enzyme (K M = 2.5 mM and V max = 102 µM•min −1 ). These findings suggest that the gel matrix has stabilized an enzyme conformation that binds tightly the substrate, but is less able to catalyze the oxidation of catechol [66]. A bi-bilayer of encapsulated enzyme was used for the development of a biosensor for detecting catechol, which is a well known pollutant.…”