A novel cheap and simple amperometric biosensor, based on the immobilization of glucose oxidase (GOD) into anionic clay; layered double hydroxides (LDHs) [Zn 3 -Al-Cl] is presented. GOD can be entrapped in the LDHs gel via electrostatic interaction. Amperometric detection of glucose with an unmediated sensor at 0.6 V (vs. SCE) results in a rapid response (5 s), a wide linear range of 0.001 -12 mM, as well as good operational stability. The low detection limit was 0.1 mM at 3s. The apparent Michaelis-Menten constant (K app M Þ is 4.4 mM. The general interferences that coexisted in blood serum do not affect glucose determination, except for uric acid. In addition, optimization of the biosensor construction and the effects of the applied potential on the amperometric response of the sensor were investigated and discussed herein.

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This paper aimed at showing the interest of the composite material based on layered double hydroxides (LDHs) and chitosan (CHT) as suitable host matrix likely to immobilize enzyme onto electrode surface for amperometric biosensing application. This hybrid material combined the advantages of inorganic LDHs and organic biopolymer, CHT. Glucose oxidase (GOD) immobilized in the composite material maintained its activity well as the usage of glutaraldehyde was avoided. The process parameters for the fabrication of the enzyme electrode and various experimental variables such as pH, applied potential and temperature, were explored for optimum analytical performance of the enzyme electrode. The enzyme electrode provided a linear response to glucose over a concentration range of 1 x 10(-6) to 3 x 10(-3) M with a high sensitivity of 62.6 mA M(-1) cm(-2) and a detection limit of 0.1 microM based on the signal-to-noise ratio of 3.

We report the fabrication of a highly sensitive dopamine biosensor based on the entrapment of tyrosinase into CaCO3 nanoparticles at Multiwalled Carbon Nanotube (MWCNT) electrodes. CaCO3 acts as host matrix for tyrosinase and MWCNT provides a highly porous conductive network enhancing the enzyme immobilization and the electrochemical transduction of the enzyme reaction by boosting the amplification phenomenon involved in the biosensing of catechol and dopamine. The comparison of the performance of CaCO3‐tyrosinase electrodes with and without MWCNT film clearly indicates the improvement in sensitivity and maximum current brought by the combination of MWCNTs and inorganic nanomaterials. These nanostructured hybrid bioelectrodes exhibit a high sensitivity for the detection of catechol and dopamine, namely 35.7 A mol−1 L cm−2, the detection limit for dopamine being 15 nmol L−1 with no influence of the presence of interferents, i.e. uric acid and ascorbic acid.