Abstract
A mesoporous, high surface area and conductive silica/titania graphite composite modified with chitosan and functionalized with tyrosinase was prepared. The composite was obtained by the sol-gel method and the surface of the resultant material was modified with chitosan solutions containing 5, 10 and 15% by mass. The textural characterization showed that even after modification with chitosan, the composite maintains a pore volume near 0.70 cm3 g-1 and pore diameter between 10 and 50 nm, adequate for enzyme immobilization. The tyrosinase was immobilized on the composite that was modified with 5% chitosan solution. A carbon ceramic electrode was manufactured with this material and was used as an electrochemical biosensor for phenolic compounds, showing low detection limits in the linear range from 40 to 350 µmol L-1 and good sensitivity of 0.284, 0.141 and 0.165 µA µmol-1 L for catechol, dopamine and pyrogallol, respectively. In this composite the enzyme showed to be operative and stable after several months.
Highlights
Phenolic compounds have been widely used in different industrial products in the medical and food fields, and their determination is very important for the quality and control of these products
The silica/titania graphite ceramic composites modified with different amounts of chitosan (CS-5, CS-10 and CS‐15 materials) were characterized by nitrogen adsorption/ desorption isotherms, and the results are shown Figure 1
It can be explained that the redox process for catechol in the electrode presented a diffusional behavior, suggesting that the silica/titania surface is covered by chitosan
Summary
Phenolic compounds have been widely used in different industrial products in the medical and food fields, and their determination is very important for the quality and control of these products. The silica/titania graphite ceramic composites modified with different amounts of chitosan (CS-5, CS-10 and CS‐15 materials) were characterized by nitrogen adsorption/ desorption isotherms, and the results are shown Figure 1.
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