Abstract-Gold screen-printed electrodes coated with thin films of layered double hydroxides containing cobalt and aluminium (Co 1.57 Al(OH) x SO 4 , shortened as CoAl) have been investigated for the design of an electrochemical tyrosinasebased biosensor used for the detection of a complex mixture of polyphenols extracted from green tea. Physicochemical analyses show that the resulted biosensor exhibits very attractive characteristics: a high sensitivity, a large dynamic range (up to 1000 ng.mL −1 ), and very low limits of detection (0.33 pg.mL −1 and 0.03 pg.mL −1 for oxidation and reduction, respectively).Index Terms-Atomic force microscopy, electrochemical biosensor, layered double hydroxide, polyphenols, tyrosinase.

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We present a new biosensor for hydrogen peroxide (H 2 O 2 ) detection. The biosensor was based on the immobilization of horseradish peroxidase (HRP) enzyme on layered double hydroxides-(LDH-) modified gold surface. The hydrotalcite LDH (Mg 2 Al) was prepared by coprecipitation in constant pH and in ambient temperature. The immobilization of the peroxidase on layered hybrid materials was realized via electrostatic adsorption autoassembly process. The detection of hydrogen peroxide was successfully observed in PBS buffer with cyclic voltammetry and the chronoamperometry techniques. A limit detection of 9 µM of H 2 O 2 was obtained with a good reproducibility. We investigate the sensitivity of our developed biosensor for H 2 O 2 detection in raw milk.

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In this work, we present the development of a hybrid biomembrane based on the immobilization of diamine oxidase (DAO) into LDH thin films for histamine detection. The LDHs preselected as host matrixes are: hydrotalcites (Mg2Al(CO3)0.5(OH)6), lowaite (Mg4Fe(OH)10Cl) and hydrocalumite (Ca2Al(OH)6Cl). The immobilized probes were characterized by atomic force microscopy (AFM) and attenuated total reflection infrared spectroscopy (IR-ATR mode). The analysis of these results shows that the immobilization of DAO occurs with all type of selected LDH and is stable after a 7 day-immersion in phosphate buffer solution. The LDH incorporating magnesium or calcium divalent cations present high-quality surface topology for DAO immobilization and the ability to keep the enzyme in a well conformation for biogenic amines catabolism and histamine detection.