title: Poly(neutral red) based hydrogen peroxide biosensor for chromium determination by inhibition measurements.
abstract: Amperometric hydrogen peroxide enzyme inhibition biosensors based on horseradish peroxidase (HRP) immobilised on electropolymerised neutral red (NR) or directly on the surface of carbon film electrodes (CFE) have been successfully applied to the determination of toxic Cr(III) and Cr(VI). Parameters influencing the performance of the biosensor including the enzyme immobilisation method, the amount of hydrogen peroxide, applied potential and electrolyte pH were optimised. The inhibition of horseradish peroxidase by the chromium species was studied under the optimised conditions. Results from the quantitative analysis of chromium ions are discussed in terms of detection limit, linear range and sensitivity. The HRP kinetic interactions reveal mixed binding of Cr(III) with I50=3.8μM and inhibition binding constant Ki=11.3μM at HRP/PNR/CFE biosensors and uncompetitive binding of Cr(VI) with I50=3.9μM and Ki=0.78μM at HRP/CFE biosensors in the presence of H2O2 substrate. Interferences from other heavy metal ions were studied and the inhibition show very good selectivity towards Cr(III) and Cr(VI).
authors: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal; Faculty of Science and Techniques, University Hassan II Mohammedia, BP 146, Mohammedia 20650, Morocco.
authors: Aisha
authors: A
authors: Attar
authors: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
authors: M
authors: M
authors: Emilia Ghica
authors: Faculty of Science and Techniques, University Hassan II Mohammedia, BP 146, Mohammedia 20650, Morocco. Electronic address: azizamine@yahoo.fr.
authors: Aziz
authors: A
authors: Amine
authors: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal. Electronic address: cbrett@ci.uc.pt.
authors: Christopher M A
authors: CM
authors: Brett
mesh_terms: D015374:Biosensing Techniques; D002857:Chromium / Q000032:analysis*; D004563:Electrochemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009499:Neutral Red / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D004800:Enzymes, Immobilized; D002857:Chromium; D009499:Neutral Red; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase
keywords: Amperometric biosensor; Cr(III); Cr(VI); Enzyme inhibition; Horseradish peroxidase; Poly(neutral red)