Fluorimetric Detection of Insulin in the Presence of Eu(III) - {Pyridine - 2,6 - Dicarboxylate} Tris Complex

Authors : Elmas GÖK, Serdar ATEŞ

Pages : 81-91

View : 11 | Download : 5

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Bovine insulin solutions insert ignore into journalissuearticles values(pH=9.3); have maximum absorption at 278 \pm 2 nm and an intrinsic emission at 305 nm when excited at 282 nm. The relative fluorescence intensities show linear dependence on its concentration: 10 mg/mL< [Ins] < 200 mg/mL. When Euinsert ignore into journalissuearticles values(PDA);33- tris complex is added to these solutions, it has a hyperchromic effect at 278 nm absorption band of insulin, sensitizing the emission intensities of central Eu3+ metal ion of the complex at 590 and 615 nm, and simultaneously quenching the emission intensity of hormone at 305 nm. Stern-Volmer plots show that a mechanism of bimolecular quenching at 305 nm and sensitization at 615 nm are valid up to a mole ratio, R = [Euinsert ignore into journalissuearticles values(PDA);33-]/[Ins] < 2.0. An intramolecular rather than an intermolecular energy transfer is proposed. An apparent binding constant, log Kapp=4.70 \pm 0.13, is calculated for Ins-[Euinsert ignore into journalissuearticles values(PDA);33-]2 type product, the presence of which may offer a new luminescence technique as a diagnostic tool and an alternative to radio-iodinated insert ignore into journalissuearticles values(131I -); insulin. A simple, rapid and accurate quantitation of insulin is proposed by using a fixed concentration of Euinsert ignore into journalissuearticles values(PDA);33-, and measuring its initial F0 at lexc/ lem=282/615 nm and the difference, DF after sensitization when \sim 100 microliters of insulin sample is added. The coefficient of variation insert ignore into journalissuearticles values(CV);, the relative error and minimum detectable amount of bovine insulin hormone are found to be 3.0%, 1.2% and 7.3 \pm 0.2 mg /mL respectively.
Keywords : Insulin, Fluorescence Spectroscopy, Eu III, Pyridine 2, 6 Dicarboxylate Tris Complex Stern Volmer Plots, Apparent Binding Constant