Synthetic nanocrystalline diamond as a third-generation biosensor support.
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.
Rubio-Retama
Jorge
J
Departamento de Química-Física II, Facultad de Farmacia, UCM, Spain. bjrubio@farm.ucm.es
Hernando
Jorge
J
López-Ruiz
Beatriz
B
Härtl
Andreas
A
Steinmüller
Doris
D
Stutzmann
Martin
M
López-Cabarcos
Enrique
E
Garrido
José Antonio
JA
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
D004800:Enzymes, Immobilized; D018130:Diamond; D006735:Horseradish Peroxidase