Metal-dispersed xerogel-based composite films for the development of interference free oxidase-based biosensors
(EN)
Prieto-Simon, B.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Prieto-Simon, B.
(EN)
We report for the first time the synthesis of metal-modified 3-aminopropyltrimethoxysilanes (APTMS) and their application for the electrochemical monitoring of hydrogen peroxide. Copper-, iron-, zinc-, and cerium-modified APTMS were mixed with tetraethoxysilane (TEOS) and the finally produced xerogels were characterized with scanning electron microscopy, energy dispersive spectrometry, nitrogen porosimetry, and thermal gravimetry. The potential of these materials as catalytic surfaces for the electrochemical monitoring of hydrogen peroxide was investigated by performing cyclic voltammetry and amperometric measurements of metal -APTMS/TEOS modified-platinum electrodes. Results show a significant increase in the sensitivity of the resulting probes compared with the sensitivity of those modified by APTMS/TEOS. However, their applicability and stability were not satisfactory due to the lack of homogeneity, low adhesion onto the electrode surface, and cracking effects during aging. The aforementioned problems were totally eliminated, and the sensitivity of the electrodes was impressively increased, when the metal-modified xerogels were applied over the platinum electrodes as a mixture in a poly(ethylene glycol) -cellulose acetate composite solution (PEG/CA). Apparent diffusion coefficients for different concentrations of PEG were determined with chronocoulometry. Resistance and wettability of the composite films were evaluated with impedance spectroscopy. Metal-APTMS/TEOS-PEG/CA composite films were also successfully tested in the construction of interference-free biosensors for glucose and hydrogen peroxide by immobilizing glucose oxidase and horseradish peroxidase, respectively, into an ethanol-free TEOS sol-gel layer developed over the composite films.
(EN)
