Performance of impedimetric biosensors based on anodically formed Ti/TiO2 electrodes

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Performance of impedimetric biosensors based on anodically formed Ti/TiO2 electrodes (EN)

Mantzila, A. G. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Mantzila, A. G. (EN)

The advantages and limitations of impedimetric sensors based on Ti/TiO2 architectures are described. Titanium dioxide (titania) was potentiostatically formed onto titanium electrodes of 2 mm diameter, at 10 and 30 V in 1 M H-2 SO4. The thickness of the titania layers was ellipsometrically determined to be 30 and 86 nm respectively and they are highly insulating with charge-transfer resistances in the M Omega range, as they were measured with electrochemical impedance spectroscopy under specific experimental conditions. Low voltage anodization (< 10V) results to amorphous TiO2, whereas at higher applied voltages (> 25 V), anatase is the predominant form. SEM images are indicative of quite smooth, compact coatings without any severe cracks. Titania films were further treated with sodium hydroxide to increase the population of hydroxyl groups onto the outer oxide layer. Various silanization procedures based on liquid and gas-phase anhydrous conditions were employed to produce amino-terminated surfaces. Using glutaraldehyde as a cross linker, avidin was immobilized by chemical bonding. All impedimetric measurements were performed using biotinylated dextran as the target analyte. The initial conductivity of titanium/titania electrodes, as it can be managed by means of the hydroxylation process (duration of chemical etching) as well as the silane layer are major factors affecting the performance of the resultant biosensors. Extended studies using electrochemical impedance spectroscopy provided important new insights into the mechanism of the signal transduction and the physical factors that control the nature of the measuring signal. (EN)

impedance sensors (EN)

Electroanalysis (EN)

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