In bio-sensor applications nafion is often used to prevent anionic interfering species (e.g ascorbate, urate etc) from reaching the electrode surface while letting the sensor sensitive to only hydrogen peroxide (lactate or glucose sensor).
Water swollen nafion gets negatively charged and we all know that's how it blocks negatively charged species. I was wondering what is the mechanism of selective analyte movement (hydrogen peroxide) through nafion membrane. How does it let other species pass through it? There are some publications on hydrogen peroxide sensors where supplementary metals are used for a redox reaction to happen between the metal and H2O2 and the membrane works as a proton exchange membrane. On the contrary, for biosensors use of bare nafion (without other substances) is quite common where H2O2 reaches to the working electrode surface to make the redox reaction happen. Is it because of the pores in the nafion membrane that lets H2O2 move through?
Thanks
The polymeric structure of Nafion contains a hydrophobic (CF2-CF2) backbone and hydrophilic sulfonic acid groups (SO3H) which contributes its electron-withdrawing
effect. it is a permselective membrane so i think on the basis of charge it repels the interfering species.
Nafion is a peifluorinated cation exchange polymer with a hydrophobic peifluoro-backbone and pendant sulfonic acid groups, which allow the permeation of hydrogen
peroxide and yet restrict the passage of anions (e.g., ascorbic acid and uric acid) across the membrane
NAfion is negatively charged polymer (sulfonate); it will electrostatically repel other anions, like ascorbate, urate. Not acting on neutral or cationic species, but anyhow, it will help to discriminate anionic species.
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