Exploitation of reversed micelles as a medium in mimetic peroxidase-catalyzed fluorogenic reaction between hydrogen peroxide and L-tyrosine

The peroxidase activity of mimetic enzyme, iron tetrasulfonatophthalocyanine (FeTSPc), was characterized in reversed micelles of hexadecyltrimethylammonium bromide (CTAB) formed in n-heptane-n-pentanol solution (2:1, V:V). The assay is based on its catalytic effect on the oxidation reaction of L-tyrosine (L-tyr) by hydrogen peroxide. The influences of environmental factors, such as the water content, CTAB concentration and pH, on the peroxidase activity of FeTSPc were investigated. It was observed that the reaction rate was distinctly enhanced in CTAB reversed micelles as compared with the rate in aqueous solution. Under optimum conditions, application of the FeTSPc-catalyzed fluorescence system in reversed micelles to the determination of H₂O₂ and FeTSPc led to a highly sensitive system compared with that in aqueous solution, permitting detection limits of 5 × 10^-9 mol 1^-1 H₂O₂ and 2.3 × 10^-9 mol 1^-1 FeTSPc. The advantages and limitations of employing the reversed micellar media in such mimetic peroxidase-catalyzed fluorescent detection schemes were discussed.