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Biosensor for H 2 O 2 Response Based on Horseradish Peroxidase: Effect of Different Mediators Adsorbed on Silica Gel Modified with Niobium Oxide
Author(s) -
Santos Antonio S.,
Durán Nelson,
Kubota Lauro T.
Publication year - 2005
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200403222
Subject(s) - biosensor , horseradish peroxidase , chemistry , hydrogen peroxide , methylene blue , thionine , adsorption , inorganic chemistry , amperometry , phenazine , phenoxazine , nuclear chemistry , catalysis , phenothiazine , electrode , organic chemistry , electrochemistry , photocatalysis , medicine , biochemistry , pharmacology , enzyme
Reagentless biosensors sensitive to hydrogen peroxide have been developed and compared. These biosensors are comprised of a carbon paste electrode modified with horseradish peroxidase (HRP) and one phenothiazine (methylene blue), one phenoxazine (meldola's blue) or one phenazine (phenazine methosulfate) dye adsorbed on silica gel modified with niobium oxide (SN). The enzyme was immobilized onto the graphite powder by cross‐linking with glutaraldehyde and mixing with one of the electron transfer mediators (dyes) adsorbed on SN. The amperometric response was based on the electrocatalytic properties of the dye to mediate electrons, which were generated in the enzymatic reaction of hydrogen peroxide under catalysis of HRP. The dependence on the biosensor response in terms of pH, buffer, HRP amounts and applied potential was investigated. The best results were found with a biosensor containing methylene blue dye showing an excellent operational stability (around 92% of the activity was maintained after 300 determinations). The proposed biosensor also presented good sensitivity (32.87 nA cm −2 μ mol −1 L) allowing hydrogen peroxide quantification at levels down to 0.52×10 −6 mol L −1 an optimum response at pH 6.8 and at a potential of −50 mV (vs. SCE) and showing a wide linear response range (from 1 to 700 μmol L −1 for hydrogen peroxide).