A fluorescence enhancement-based sensor using glycosylated metalloporphyrin as a recognition element for levamisole assay

A fluorescence sensor based on the supermolecular recognition by glycosylated metalloporphyrin for levamisole (LEV) assay is reported. For the preparation of a LEV-sensitive active material, 5, 10, 15, 20-tetrakis[2-(2, 3, 4, 6-tetraacetyl-beta-D-glucopyranosyl)-1-O-phenyl] porphyrin and its metal complexes were synthesized and used in an optode membrane prepared by including glycosylated metalloporphyrin in chitosan matrice. The immobilized glycosylated metalloporphyrin is shown to be weakly fluorescent as a result of the inhibiting of the electron tansfer by central metal. The fluorescence enhancement of the metalloporphyrin modified optode membrane by LEV is based on the complexation with the central metal moiety of metalloporphyrin and weakening the inhibiting of the electron tansfer for metalloporphyrin. The glycosylated metalloporphyrin/chitosan optode membrane showed excellent selectivity toward LEV with respect to a number of interferents and exhibited stable response. The calibration graph obtained with the proposed sensor was linear over the range of 1.3x10(-5)-3.5x10(-7)ML(-1), with a detection limit of 3.5x10(-7)ML(-1) for LEV. The prepared sensor is applied for the determination of LEV in pharmaceutical preparations and the results agreed with the values obtained by the pharmacopoeia method.