HRP/[Zn-Cr-ABTS] redox clay-based biosensor: design and optimization for cyanide detection

A novel inexpensive and simple amperometric biosensor, based on the immobilization of HRP into redox active [Zn-Cr-ABTS] layered double hydroxide, is applied to the determination of cyanide. The electrochemical transduction step corresponds to the reduction at 0.0 V of ABTS(+.) enzymatically formed in the presence of H2O2. The biosensor has a fast response to H2O2 (8 s) with a linear range of 1.7 x 10(-9) to 2.1 x 10(-6) M and a sensitivity of 875 mA M-1 cm(-2). The apparent Michaelis-Menten constant (K-M(app)) is 12 muM. The detection of cyanide is performed via its non competitive inhibiting action on the HRP/[Zn-Cr-ABTS] electrode. The concentration range of the linear response and the apparent inhibition constant (k(i)) are 5 x 10-9 to 4 x 10(-8) and 1.4 x 10(-7) M, respectively. (C) 2004 Elsevier B.V. All rights reserved.