SiO2/SnO2/Sb2O5 microporous ceramic material for immobilization of Meldola's blue: application as an electrochemical sensor for NADH.
The mixed oxide SiO(2)/SnO(2), containing 25 wt% of SnO(2), determined by X-ray fluorescence, was prepared by the sol-gel method and the porous matrix obtained was then grafted with Sb (V), resulting the solid designated as (SiSnSb). XPS indicated 0.7% of Sb atoms on the surface. Sb grafted on the surface contains Brønsted acid centers (SbOH groups) that can immobilize Meldola's blue (MB(+)) cationic dye onto the surface by an ion exchange reaction, resulting the solid designated as (SiSnSb/MB). In the present case a surface concentration of MB(+)=2.5×10(-11) mol cm(2) on the surface was obtained. A homogeneous mixture of the SiSnSb/MB with ultra pure graphite (99.99%) was pressed in disk format and used to fabricate a working electrode that displayed an excellent specific electrocatalytic response to NADH oxidation, with a formal potential of -0.05 V at pH 7.3. The electrochemical properties of the resulting electrode were investigated thoroughly with cyclic voltammetric and chronoamperometry techniques. The proposed sensor showed a good linear response range for NADH concentrations between 8×10(-5) and 9.0×10(-4) mol L(-1), with a detection limit of 1.5×10(-7) mol L(-1). The presence of dopamine and ascorbic acid did not show any interference in the detection of NADH on this modified electrode surface.
Institute of Chemistry, State University of Campinas, P.O. Box 6154, 13084-971 Campinas, SP, Brazil.
Thiago C
TC
Canevari
Rita C G
RC
Vinhas
Richard
R
Landers
Yoshitaka
Y
Gushikem
D015374:Biosensing Techniques / Q000295:instrumentation*; D002516:Ceramics / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D009243:NAD / Q000032:analysis* / Q000737:chemistry; D010078:Oxazines / Q000737:chemistry*; D016062:Porosity
D020099:Coated Materials, Biocompatible; D010078:Oxazines; D009243:NAD; C005559:Meldola blue