title: Synthetic nanocrystalline diamond as a third-generation biosensor support.
abstract: Horseradish peroxidase (HRP) has been immobilized on the surface of functionalized nanocrystalline diamond (NCD) thin films. The structure of the modified NCD surface as well as the electrochemical behavior of the whole system was characterized by impedance spectroscopy and cyclic voltammetry. The proximity of HRP heme groups to the NCD surface allowed direct electron transfer between them, resulting in two separated one-electron-transfer peaks at 0.05 V and 0.29 V vs Ag/AgCl, corresponding to the cathodic and anodic process, respectively. The heterogeneous electron-transfer constant for both processes was calculated to be 0.066 s(-1), the charge-transfer coefficient alpha = 0.49, and the immobilized enzymatic layer about 2.10(-10) mol/cm2. The modified NCD electrode was used as a third-generation biosensor for hydrogen peroxide determination showing a linear response in the 0.1-45 mM H2O2 range, at +0.05 V vs Ag/AgCl.
authors.affiliation: Departamento de Química-Física II, Facultad de Farmacia, UCM, Spain. bjrubio@farm.ucm.es
authors.forename: Jorge
authors.initials: J
authors.lastname: Rubio-Retama
authors.forename: Jorge
authors.initials: J
authors.lastname: Hernando
authors.forename: Beatriz
authors.initials: B
authors.lastname: López-Ruiz
authors.forename: Andreas
authors.initials: A
authors.lastname: Härtl
authors.forename: Doris
authors.initials: D
authors.lastname: Steinmüller
authors.forename: Martin
authors.initials: M
authors.lastname: Stutzmann
authors.forename: Enrique
authors.initials: E
authors.lastname: López-Cabarcos
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garrido
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D018130:Diamond / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004800:Enzymes, Immobilized; D018130:Diamond; D006735:Horseradish Peroxidase